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| Publications of Dale Purves :chronological alphabetical combined listing:
%% Books
@book{fds370321,
Author = {Purves, D},
Title = {Why Brains Don't Compute},
Pages = {1-168},
Year = {2021},
Month = {May},
ISBN = {9783030710637},
url = {http://dx.doi.org/10.1007/978-3-030-71064-4},
Abstract = {This book examines what seems to be the basic challenge in
neuroscience today: understanding how experience generated
by the human brain is related to the physical world we live
in. The 25 short chapters present the argument and evidence
that brains address this problem on a wholly trial and error
basis. The goal is to encourage neuroscientists, computer
scientists, philosophers, and other interested readers to
consider this concept of neural function and its
implications, not least of which is the conclusion that
brains don't "compute."},
Doi = {10.1007/978-3-030-71064-4},
Key = {fds370321}
}
%% Papers Published
@article{fds345466,
Author = {Purves, D},
Title = {Opinion: What does AI's success playing complex board games
tell brain scientists?},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {116},
Number = {30},
Pages = {14785-14787},
Year = {2019},
Month = {July},
url = {http://dx.doi.org/10.1073/pnas.1909565116},
Doi = {10.1073/pnas.1909565116},
Key = {fds345466}
}
@article{fds346898,
Author = {Ng, CJ and Purves, D},
Title = {An Alternative Theory of Binocularity.},
Journal = {Frontiers in Computational Neuroscience},
Volume = {13},
Pages = {71},
Year = {2019},
Month = {January},
url = {http://dx.doi.org/10.3389/fncom.2019.00071},
Abstract = {The fact that seeing with two eyes is universal among
vertebrates raises a problem that has long challenged vision
scientists: how do animals with overlapping visual fields
combine non-identical right and left eye images to achieve
fusion and the perception of depth that follows? Most
theories address this problem in terms of matching
corresponding images on the right and left retinas. Here we
suggest an alternative theory of binocular vision based on
anatomical correspondence that circumvents the
correspondence problem and provides a rationale for ocular
dominance.},
Doi = {10.3389/fncom.2019.00071},
Key = {fds346898}
}
@article{fds336007,
Author = {Bowling, DL and Purves, D and Gill, KZ},
Title = {Reply to Goffinet: In consonance, old ideas die
hard.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {115},
Number = {22},
Pages = {E4958-E4959},
Year = {2018},
Month = {May},
url = {http://dx.doi.org/10.1073/pnas.1805570115},
Doi = {10.1073/pnas.1805570115},
Key = {fds336007}
}
@article{fds331493,
Author = {Bowling, DL and Purves, D and Gill, KZ},
Title = {Vocal similarity predicts the relative attraction of musical
chords.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {115},
Number = {1},
Pages = {216-221},
Year = {2018},
Month = {January},
url = {http://dx.doi.org/10.1073/pnas.1713206115},
Abstract = {Musical chords are combinations of two or more tones played
together. While many different chords are used in music,
some are heard as more attractive (consonant) than others.
We have previously suggested that, for reasons of biological
advantage, human tonal preferences can be understood in
terms of the spectral similarity of tone combinations to
harmonic human vocalizations. Using the chromatic scale, we
tested this theory further by assessing the perceived
consonance of all possible dyads, triads, and tetrads within
a single octave. Our results show that the consonance of
chords is predicted by their relative similarity to voiced
speech sounds. These observations support the hypothesis
that the relative attraction of musical tone combinations is
due, at least in part, to the biological advantages that
accrue from recognizing and responding to conspecific vocal
stimuli.},
Doi = {10.1073/pnas.1713206115},
Key = {fds331493}
}
@article{fds348739,
Author = {Purves, D and Yegappan, C},
Title = {The Demands of Geometry on Color Vision.},
Journal = {Vision (Basel, Switzerland)},
Volume = {1},
Number = {1},
Pages = {E9},
Year = {2017},
Month = {January},
url = {http://dx.doi.org/10.3390/vision1010009},
Abstract = {While studies of human color vision have made enormous
strides, an overarching rationale for the circular sense of
color relationships generated by two classes of color
opponent neurons and three cone types is still lacking. Here
we suggest that color circularity, color opponency and
trichromacy may have arisen, at least in part, because of
the geometrical requirements needed to unambiguously
distinguish all possible spectrally different regions on a
plane.},
Doi = {10.3390/vision1010009},
Key = {fds348739}
}
@article{fds268347,
Author = {Bowling, DL and Purves, D},
Title = {A biological rationale for musical consonance.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {112},
Number = {36},
Pages = {11155-11160},
Year = {2015},
Month = {September},
ISSN = {0027-8424},
url = {http://dx.doi.org/10.1073/pnas.1505768112},
Abstract = {The basis of musical consonance has been debated for
centuries without resolution. Three interpretations have
been considered: (i) that consonance derives from the
mathematical simplicity of small integer ratios; (ii) that
consonance derives from the physical absence of interference
between harmonic spectra; and (iii) that consonance derives
from the advantages of recognizing biological vocalization
and human vocalization in particular. Whereas the
mathematical and physical explanations are at odds with the
evidence that has now accumulated, biology provides a
plausible explanation for this central issue in music and
audition.},
Doi = {10.1073/pnas.1505768112},
Key = {fds268347}
}
@article{fds359924,
Author = {Purves, D and Morgenstern, Y and Wojtach, WT},
Title = {Will understanding vision require a wholly empirical
paradigm?},
Journal = {Frontiers in Psychology},
Volume = {6},
Pages = {1072},
Year = {2015},
Month = {January},
url = {http://dx.doi.org/10.3389/fpsyg.2015.01072},
Abstract = {Based on electrophysiological and anatomical studies, a
prevalent conception is that the visual system recovers
features of the world from retinal images to generate
perceptions and guide behavior. This paradigm, however, is
unable to explain why visual perceptions differ from
physical measurements, or how behavior could routinely
succeed on this basis. An alternative is that vision does
not recover features of the world, but assigns perceptual
qualities empirically by associating frequently occurring
stimulus patterns with useful responses on the basis of
survival and reproductive success. The purpose of the
present article is to briefly describe this strategy of
vision and the evidence for it.},
Doi = {10.3389/fpsyg.2015.01072},
Key = {fds359924}
}
@article{fds323313,
Author = {Purves, D and Morgenstern, Y and Wojtach, WT},
Title = {Perception and Reality: Why a Wholly Empirical Paradigm is
Needed to Understand Vision.},
Journal = {Frontiers in Systems Neuroscience},
Volume = {9},
Pages = {156},
Year = {2015},
Month = {January},
url = {http://dx.doi.org/10.3389/fnsys.2015.00156},
Abstract = {A central puzzle in vision science is how perceptions that
are routinely at odds with physical measurements of real
world properties can arise from neural responses that
nonetheless lead to effective behaviors. Here we argue that
the solution depends on: (1) rejecting the assumption that
the goal of vision is to recover, however imperfectly,
properties of the world; and (2) replacing it with a
paradigm in which perceptions reflect biological utility
based on past experience rather than objective features of
the environment. Present evidence is consistent with the
conclusion that conceiving vision in wholly empirical terms
provides a plausible way to understand what we see and
why.},
Doi = {10.3389/fnsys.2015.00156},
Key = {fds323313}
}
@article{fds268349,
Author = {Morgenstern, Y and Rostami, M and Purves, D},
Title = {Properties of artificial networks evolved to contend with
natural spectra.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {111 Suppl 3},
Pages = {10868-10872},
Year = {2014},
Month = {July},
ISSN = {0027-8424},
url = {http://dx.doi.org/10.1073/pnas.1402669111},
Abstract = {Understanding why spectra that are physically the same
appear different in different contexts (color contrast),
whereas spectra that are physically different appear similar
(color constancy) presents a major challenge in vision
research. Here, we show that the responses of biologically
inspired neural networks evolved on the basis of accumulated
experience with spectral stimuli automatically generate
contrast and constancy. The results imply that these
phenomena are signatures of a strategy that biological
vision uses to circumvent the inverse optics problem as it
pertains to light spectra, and that double-opponent neurons
in early-level vision evolve to serve this purpose. This
strategy provides a way of understanding the peculiar
relationship between the objective world and subjective
color experience, as well as rationalizing the relevant
visual circuitry without invoking feature detection or image
representation.},
Doi = {10.1073/pnas.1402669111},
Key = {fds268349}
}
@article{fds268350,
Author = {Purves, D and Monson, BB and Sundararajan, J and Wojtach,
WT},
Title = {How biological vision succeeds in the physical
world.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {111},
Number = {13},
Pages = {4750-4755},
Year = {2014},
Month = {April},
ISSN = {0027-8424},
url = {http://dx.doi.org/10.1073/pnas.1311309111},
Abstract = {Biological visual systems cannot measure the properties that
define the physical world. Nonetheless, visually guided
behaviors of humans and other animals are routinely
successful. The purpose of this article is to consider how
this feat is accomplished. Most concepts of vision propose,
explicitly or implicitly, that visual behavior depends on
recovering the sources of stimulus features either directly
or by a process of statistical inference. Here we argue
that, given the inability of the visual system to access the
properties of the world, these conceptual frameworks cannot
account for the behavioral success of biological vision. The
alternative we present is that the visual system links the
frequency of occurrence of biologically determined stimuli
to useful perceptual and behavioral responses without
recovering real-world properties. The evidence for this
interpretation of vision is that the frequency of occurrence
of stimulus patterns predicts many basic aspects of what we
actually see. This strategy provides a different way of
conceiving the relationship between objective reality and
subjective experience, and offers a way to understand the
operating principles of visual circuitry without invoking
feature detection, representation, or probabilistic
inference.},
Doi = {10.1073/pnas.1311309111},
Key = {fds268350}
}
@article{fds268348,
Author = {Morgenstern, Y and Rukmini, DV and Monson, BB and Purves,
D},
Title = {Properties of artificial neurons that report lightness based
on accumulated experience with luminance.},
Journal = {Frontiers in Computational Neuroscience},
Volume = {8},
Pages = {134},
Year = {2014},
Month = {January},
url = {http://dx.doi.org/10.3389/fncom.2014.00134},
Abstract = {The responses of visual neurons in experimental animals have
been extensively characterized. To ask whether these
responses are consistent with a wholly empirical concept of
visual perception, we optimized simple neural networks that
responded according to the cumulative frequency of
occurrence of local luminance patterns in retinal images.
Based on this estimation of accumulated experience, the
neuron responses showed classical center-surround receptive
fields, luminance gain control and contrast gain control,
the key properties of early level visual neurons determined
in animal experiments. These results imply that a major
purpose of pre-cortical neuronal circuitry is to contend
with the inherently uncertain significance of luminance
values in natural stimuli.},
Doi = {10.3389/fncom.2014.00134},
Key = {fds268348}
}
@article{fds268352,
Author = {Monson, BB and Han, S and Purves, D},
Title = {Are auditory percepts determined by experience?},
Journal = {Plos One},
Volume = {8},
Number = {5},
Pages = {e63728},
Year = {2013},
Month = {January},
url = {http://www.ncbi.nlm.nih.gov/pubmed/23667666},
Abstract = {Audition--what listeners hear--is generally studied in terms
of the physical properties of sound stimuli and
physiological properties of the auditory system. Based on
recent work in vision, we here consider an alternative
perspective that sensory percepts are based on past
experience. In this framework, basic auditory qualities
(e.g., loudness and pitch) are based on the frequency of
occurrence of stimulus patterns in natural acoustic stimuli.
To explore this concept of audition, we examined five
well-documented psychophysical functions. The frequency of
occurrence of acoustic patterns in a database of natural
sound stimuli (speech) predicts some qualitative aspects of
these functions, but with substantial quantitative
discrepancies. This approach may offer a rationale for
auditory phenomena that are difficult to explain in terms of
the physical attributes of the stimuli as
such.},
Doi = {10.1371/journal.pone.0063728},
Key = {fds268352}
}
@article{fds268353,
Author = {Ng, C and Sundararajan, J and Hogan, M and Purves,
D},
Title = {Network connections that evolve to circumvent the inverse
optics problem.},
Journal = {Plos One},
Volume = {8},
Number = {3},
Pages = {e60490},
Year = {2013},
Month = {January},
url = {http://www.ncbi.nlm.nih.gov/pubmed/23555981},
Abstract = {A fundamental problem in vision science is how useful
perceptions and behaviors arise in the absence of
information about the physical sources of retinal stimuli
(the inverse optics problem). Psychophysical studies show
that human observers contend with this problem by using the
frequency of occurrence of stimulus patterns in cumulative
experience to generate percepts. To begin to understand the
neural mechanisms underlying this strategy, we examined the
connectivity of simple neural networks evolved to respond
according to the cumulative rank of stimulus luminance
values. Evolved similarities with the connectivity of early
level visual neurons suggests that biological visual
circuitry uses the same mechanisms as a means of creating
useful perceptions and behaviors without information about
the real world.},
Doi = {10.1371/journal.pone.0060490},
Key = {fds268353}
}
@article{fds268472,
Author = {Bowling, DL and Sundararajan, J and Han, S and Purves,
D},
Title = {Expression of emotion in Eastern and Western music mirrors
vocalization.},
Journal = {Plos One},
Volume = {7},
Number = {3},
Pages = {e31942},
Year = {2012},
Month = {January},
url = {http://www.ncbi.nlm.nih.gov/pubmed/22431970},
Abstract = {In Western music, the major mode is typically used to convey
excited, happy, bright or martial emotions, whereas the
minor mode typically conveys subdued, sad or dark emotions.
Recent studies indicate that the differences between these
modes parallel differences between the prosodic and spectral
characteristics of voiced speech sounds uttered in
corresponding emotional states. Here we ask whether tonality
and emotion are similarly linked in an Eastern musical
tradition. The results show that the tonal relationships
used to express positive/excited and negative/subdued
emotions in classical South Indian music are much the same
as those used in Western music. Moreover, tonal variations
in the prosody of English and Tamil speech uttered in
different emotional states are parallel to the tonal trends
in music. These results are consistent with the hypothesis
that the association between musical tonality and emotion is
based on universal vocal characteristics of different
affective states.},
Doi = {10.1371/journal.pone.0031942},
Key = {fds268472}
}
@article{fds268471,
Author = {Purves, D and Wojtach, WT and Lotto, RB},
Title = {Understanding vision in wholly empirical
terms.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {108 Suppl 3},
Pages = {15588-15595},
Year = {2011},
Month = {September},
url = {http://www.ncbi.nlm.nih.gov/pubmed/21383192},
Abstract = {This article considers visual perception, the nature of the
information on which perceptions seem to be based, and the
implications of a wholly empirical concept of perception and
sensory processing for vision science. Evidence from studies
of lightness, brightness, color, form, and motion all
indicate that, because the visual system cannot access the
physical world by means of retinal light patterns as such,
what we see cannot and does not represent the actual
properties of objects or images. The phenomenology of visual
perceptions can be explained, however, in terms of empirical
associations that link images whose meanings are inherently
undetermined to their behavioral significance. Vision in
these terms requires fundamentally different concepts of
what we see, why, and how the visual system
operates.},
Doi = {10.1073/pnas.1012178108},
Key = {fds268471}
}
@article{fds268470,
Author = {Lotto, RB and Clarke, R and Corney, D and Purves,
D},
Title = {Seeing in colour},
Journal = {Optics & Laser Technology},
Volume = {43},
Number = {2},
Pages = {261-269},
Publisher = {Elsevier BV},
Year = {2011},
Month = {March},
ISSN = {0030-3992},
url = {http://dx.doi.org/10.1016/j.optlastec.2010.02.006},
Abstract = {Understanding perception of colour is challenging because
what we see is not always what is there, which is a
phenomenon we call illusions. Here we review the nature of
colour vision, and the problems facing most current models
and explanations. Focusing on our recent research on humans,
bees and computers, we describe a new, more ecologically
based explanation that provides a clear framework for why we
see what we do. © 2010 Elsevier Ltd. All rights
reserved.},
Doi = {10.1016/j.optlastec.2010.02.006},
Key = {fds268470}
}
@article{fds268469,
Author = {Han, SE and Sundararajan, J and Bowling, DL and Lake, J and Purves,
D},
Title = {Co-variation of tonality in the music and speech of
different cultures.},
Journal = {Plos One},
Volume = {6},
Number = {5},
Pages = {e20160},
Year = {2011},
Month = {January},
url = {http://www.ncbi.nlm.nih.gov/pubmed/21637716},
Abstract = {Whereas the use of discrete pitch intervals is
characteristic of most musical traditions, the size of the
intervals and the way in which they are used is culturally
specific. Here we examine the hypothesis that these
differences arise because of a link between the tonal
characteristics of a culture's music and its speech. We
tested this idea by comparing pitch intervals in the
traditional music of three tone language cultures (Chinese,
Thai and Vietnamese) and three non-tone language cultures
(American, French and German) with pitch intervals between
voiced speech segments. Changes in pitch direction occur
more frequently and pitch intervals are larger in the music
of tone compared to non-tone language cultures. More
frequent changes in pitch direction and larger pitch
intervals are also apparent in the speech of tone compared
to non-tone language cultures. These observations suggest
that the different tonal preferences apparent in music
across cultures are closely related to the differences in
the tonal characteristics of voiced speech.},
Doi = {10.1371/journal.pone.0020160},
Key = {fds268469}
}
@article{fds268466,
Author = {Bowling, DL and Gill, K and Choi, JD and Prinz, J and Purves,
D},
Title = {Major and minor music compared to excited and subdued
speech.},
Journal = {The Journal of the Acoustical Society of
America},
Volume = {127},
Number = {1},
Pages = {491-503},
Year = {2010},
Month = {January},
url = {http://www.ncbi.nlm.nih.gov/pubmed/20058994},
Abstract = {The affective impact of music arises from a variety of
factors, including intensity, tempo, rhythm, and tonal
relationships. The emotional coloring evoked by intensity,
tempo, and rhythm appears to arise from association with the
characteristics of human behavior in the corresponding
condition; however, how and why particular tonal
relationships in music convey distinct emotional effects are
not clear. The hypothesis examined here is that major and
minor tone collections elicit different affective reactions
because their spectra are similar to the spectra of voiced
speech uttered in different emotional states. To evaluate
this possibility the spectra of the intervals that
distinguish major and minor music were compared to the
spectra of voiced segments in excited and subdued speech
using fundamental frequency and frequency ratios as
measures. Consistent with the hypothesis, the spectra of
major intervals are more similar to spectra found in excited
speech, whereas the spectra of particular minor intervals
are more similar to the spectra of subdued speech. These
results suggest that the characteristic affective impact of
major and minor tone collections arises from associations
routinely made between particular musical intervals and
voiced speech.},
Doi = {10.1121/1.3268504},
Key = {fds268466}
}
@article{fds268465,
Author = {Gill, KZ and Purves, D},
Title = {A biological rationale for musical scales.},
Journal = {Plos One},
Volume = {4},
Number = {12},
Pages = {e8144},
Year = {2009},
Month = {December},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19997506},
Abstract = {Scales are collections of tones that divide octaves into
specific intervals used to create music. Since humans can
distinguish about 240 different pitches over an octave in
the mid-range of hearing, in principle a very large number
of tone combinations could have been used for this purpose.
Nonetheless, compositions in Western classical, folk and
popular music as well as in many other musical traditions
are based on a relatively small number of scales that
typically comprise only five to seven tones. Why humans
employ only a few of the enormous number of possible tone
combinations to create music is not known. Here we show that
the component intervals of the most widely used scales
throughout history and across cultures are those with the
greatest overall spectral similarity to a harmonic series.
These findings suggest that humans prefer tone combinations
that reflect the spectral characteristics of conspecific
vocalizations. The analysis also highlights the spectral
similarity among the scales used by different
cultures.},
Doi = {10.1371/journal.pone.0008144},
Key = {fds268465}
}
@article{fds268468,
Author = {Wojtach, WT and Sung, K and Purves, D},
Title = {An empirical explanation of the speed-distance
effect.},
Journal = {Plos One},
Volume = {4},
Number = {8},
Pages = {e6771},
Year = {2009},
Month = {August},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19707552},
Abstract = {Understanding motion perception continues to be the subject
of much debate, a central challenge being to account for why
the speeds and directions seen accord with neither the
physical movements of objects nor their projected movements
on the retina. Here we investigate the varied perceptions of
speed that occur when stimuli moving across the retina
traverse different projected distances (the speed-distance
effect). By analyzing a database of moving objects projected
onto an image plane we show that this phenomenology can be
quantitatively accounted for by the frequency of occurrence
of image speeds generated by perspective transformation.
These results indicate that speed-distance effects are
determined empirically from accumulated past experience with
the relationship between image speeds and moving
objects.},
Doi = {10.1371/journal.pone.0006771},
Key = {fds268468}
}
@article{fds268351,
Author = {Purves, D},
Title = {Perception of Surfaces and Forms},
Pages = {513-521},
Publisher = {Elsevier},
Year = {2009},
Month = {January},
url = {http://dx.doi.org/10.1016/B978-008045046-9.00229-1},
Abstract = {The purpose of this article is to consider the strategy that
vision uses to generate perceptions of surface qualities
such as brightness and color, as well as perceptions of
surface form. The basic challenge that vision must contend
with in elaborating these subjective experiences is linking
inherently ambiguous retinal stimuli to their real-world
sources in a manner that leads to successful visually guided
behavior. The evidence derived from what people actually see
indicates that this problem is solved in a fundamentally
empirical manner - that is, by the accumulation of past
experience rather than by analytical operations on visual
stimulus features. © 2009 Elsevier Ltd All rights
reserved.},
Doi = {10.1016/B978-008045046-9.00229-1},
Key = {fds268351}
}
@article{fds268467,
Author = {Sung, K and Wojtach, WT and Purves, D},
Title = {An empirical explanation of aperture effects.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {106},
Number = {1},
Pages = {298-303},
Year = {2009},
Month = {January},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19114661},
Abstract = {The perceived direction of a moving line changes, often
markedly, when viewed through an aperture. Although several
explanations of this remarkable effect have been proposed,
these accounts typically focus on the percepts elicited by a
particular type of aperture and offer no biological
rationale. Here, we test the hypothesis that to contend with
the inherently ambiguous nature of motion stimuli the
perceived direction of objects moving behind apertures of
different shapes is determined by a wholly empirical
strategy of visual processing. An analysis of moving line
stimuli generated by objects projected through apertures
shows that the directions of motion subjects report in
psychophysical testing is accounted for by the frequency of
occurrence of the 2D directions of stimuli generated by
simulated 3D sources. The completeness of these predictions
supports the conclusion that the direction of perceived
motion is fully determined by accumulated behavioral
experience with sources whose physical motions cannot be
conveyed by image sequences as such.},
Doi = {10.1073/pnas.0811702106},
Key = {fds268467}
}
@article{fds268464,
Author = {Gill, KZ and Purves, D},
Title = {A biological rationale for musical scales.},
Journal = {Plos One},
Volume = {4},
Number = {12},
Pages = {e8144},
Year = {2009},
ISSN = {1932-6203},
Abstract = {Scales are collections of tones that divide octaves into
specific intervals used to create music. Since humans can
distinguish about 240 different pitches over an octave in
the mid-range of hearing, in principle a very large number
of tone combinations could have been used for this purpose.
Nonetheless, compositions in Western classical, folk and
popular music as well as in many other musical traditions
are based on a relatively small number of scales that
typically comprise only five to seven tones. Why humans
employ only a few of the enormous number of possible tone
combinations to create music is not known. Here we show that
the component intervals of the most widely used scales
throughout history and across cultures are those with the
greatest overall spectral similarity to a harmonic series.
These findings suggest that humans prefer tone combinations
that reflect the spectral characteristics of conspecific
vocalizations. The analysis also highlights the spectral
similarity among the scales used by different
cultures.},
Key = {fds268464}
}
@article{fds268462,
Author = {Wojtach, WT and Sung, K and Truong, S and Purves,
D},
Title = {An empirical explanation of the flash-lag
effect.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {105},
Number = {42},
Pages = {16338-16343},
Year = {2008},
Month = {October},
url = {http://www.ncbi.nlm.nih.gov/pubmed/18852459},
Abstract = {When a flash of light is presented in physical alignment
with a moving object, the flash is perceived to lag behind
the position of the object. This phenomenon, known as the
flash-lag effect, has been of particular interest to vision
scientists because of the challenge it presents to
understanding how the visual system generates perceptions of
objects in motion. Although various explanations have been
offered, the significance of this effect remains a matter of
debate. Here, we show that: (i) contrary to previous reports
based on limited data, the flash-lag effect is an increasing
nonlinear function of image speed; and (ii) this function is
accurately predicted by the frequency of occurrence of image
speeds generated by the perspective transformation of moving
objects. These results support the conclusion that
perceptions of the relative position of a moving object are
determined by accumulated experience with image speeds, in
this way allowing for visual behavior in response to
real-world sources whose speeds and positions cannot be
perceived directly.},
Doi = {10.1073/pnas.0808916105},
Key = {fds268462}
}
@article{fds268463,
Author = {Ross, D and Choi, J and Purves, D},
Title = {Musical intervals in speech.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {104},
Number = {23},
Pages = {9852-9857},
Year = {2007},
Month = {June},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/17525146},
Abstract = {Throughout history and across cultures, humans have created
music using pitch intervals that divide octaves into the 12
tones of the chromatic scale. Why these specific intervals
in music are preferred, however, is not known. In the
present study, we analyzed a database of individually spoken
English vowel phones to examine the hypothesis that musical
intervals arise from the relationships of the formants in
speech spectra that determine the perceptions of distinct
vowels. Expressed as ratios, the frequency relationships of
the first two formants in vowel phones represent all 12
intervals of the chromatic scale. Were the formants to fall
outside the ranges found in the human voice, their
relationships would generate either a less complete or a
more dilute representation of these specific intervals.
These results imply that human preference for the intervals
of the chromatic scale arises from experience with the way
speech formants modulate laryngeal harmonics to create
different phonemes.},
Doi = {10.1073/pnas.0703140104},
Key = {fds268463}
}
@article{fds268461,
Author = {Boots, B and Nundy, S and Purves, D},
Title = {Evolution of visually guided behavior in artificial
agents.},
Journal = {Network: Computation in Neural Systems},
Volume = {18},
Number = {1},
Pages = {11-34},
Year = {2007},
Month = {March},
ISSN = {0954-898X},
url = {http://www.ncbi.nlm.nih.gov/pubmed/17454680},
Abstract = {Recent work on brightness, color, and form has suggested
that human visual percepts represent the probable sources of
retinal images rather than stimulus features as such. Here
we investigate the plausibility of this empirical concept of
vision by allowing autonomous agents to evolve in virtual
environments based solely on the relative success of their
behavior. The responses of evolved agents to visual stimuli
indicate that fitness improves as the neural network control
systems gradually incorporate the statistical relationship
between projected images and behavior appropriate to the
sources of the inherently ambiguous images. These results:
(1) demonstrate the merits of a wholly empirical strategy of
animal vision as a means of contending with the inverse
optics problem; (2) argue that the information incorporated
into biological visual processing circuitry is the
relationship between images and their probable sources; and
(3) suggest why human percepts do not map neatly onto
physical reality.},
Doi = {10.1080/09548980601113254},
Key = {fds268461}
}
@article{fds268460,
Author = {Howe, CQ and Beau Lotto and R and Purves, D},
Title = {Comparison of Bayesian and empirical ranking approaches to
visual perception.},
Journal = {Journal of Theoretical Biology},
Volume = {241},
Number = {4},
Pages = {866-875},
Year = {2006},
Month = {August},
ISSN = {0022-5193},
url = {http://www.ncbi.nlm.nih.gov/pubmed/16537082},
Abstract = {Much current vision research is predicated on the idea--and
a rapidly growing body of evidence--that visual percepts are
generated according to the empirical significance of light
stimuli rather than their physical characteristics. As a
result, an increasing number of investigators have asked how
visual perception can be rationalized in these terms. Here,
we compare two different theoretical frameworks for
predicting what observers actually see in response to visual
stimuli: Bayesian decision theory and empirical ranking
theory. Deciding which of these approaches has greater merit
is likely to determine how the statistical operations that
apparently underlie visual perception are eventually
understood.},
Doi = {10.1016/j.jtbi.2006.01.017},
Key = {fds268460}
}
@article{fds268457,
Author = {Long, F and Yang, Z and Purves, D},
Title = {Spectral statistics in natural scenes predict hue,
saturation, and brightness.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {103},
Number = {15},
Pages = {6013-6018},
Year = {2006},
Month = {April},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/16595630},
Abstract = {The perceptual color qualities of hue, saturation, and
brightness do not correspond in any simple way to the
physical characteristics of retinal stimuli, a fact that
poses a major obstacle for any explanation of color vision.
Here we test the hypothesis that these basic color
attributes are determined by the statistical covariations in
the spectral stimuli that humans have always experienced in
typical visual environments. Using a database of 1,600
natural images, we analyzed the joint probability
distributions of the physical variables most relevant to
each of these perceptual qualities. The cumulative density
functions derived from these distributions predict the major
colorimetric functions that have been reported in
psychophysical experiments over the last
century.},
Doi = {10.1073/pnas.0600890103},
Key = {fds268457}
}
@article{fds268459,
Author = {Holcombe, AO and Clifford, CWG and Eagleman, DM and Pakarian,
P},
Title = {Illusory motion reversal in tune with motion
detectors.},
Journal = {Trends in Cognitive Sciences},
Volume = {9},
Number = {12},
Pages = {559-560},
Year = {2005},
Month = {December},
ISSN = {1364-6613},
url = {http://dx.doi.org/10.1016/j.tics.2005.10.009},
Doi = {10.1016/j.tics.2005.10.009},
Key = {fds268459}
}
@article{fds268458,
Author = {Andrews, T and Purves, D},
Title = {The wagon-wheel illusion in continuous light.},
Journal = {Trends in Cognitive Sciences},
Volume = {9},
Number = {6},
Pages = {261-263},
Year = {2005},
Month = {June},
url = {http://dx.doi.org/10.1016/j.tics.2005.04.004},
Abstract = {The fact that a perceptual experience akin to the familiar
wagon-wheel illusion in movies and on TV can occur in the
absence of stroboscopic presentation is intriguing because
of its relevance to visuo-temporal parsing. The wagon-wheel
effect in continuous light has also been the source of
considerable misunderstanding and dispute, as is apparent in
a series of recent papers. Here we review this potentially
confusing evidence and suggest how it should be
interpreted.},
Doi = {10.1016/j.tics.2005.04.004},
Key = {fds268458}
}
@article{fds268455,
Author = {Howe, CQ and Yang, Z and Purves, D},
Title = {The Poggendorff illusion explained by natural scene
geometry.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {102},
Number = {21},
Pages = {7707-7712},
Year = {2005},
Month = {May},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/15888555},
Abstract = {One of the most intriguing of the many discrepancies between
perceived spatial relationships and the physical structure
of visual stimuli is the Poggendorff illusion, when an
obliquely oriented line that is interrupted no longer
appears collinear. Although many different theories have
been proposed to explain this effect, there has been no
consensus about its cause. Here, we use a database of range
images (i.e., images that include the distance from the
image plane of every pixel in the scene) to show that the
probability distribution of the possible locations of line
segments across an interval in natural environments can
fully account for all of the behavior of this otherwise
puzzling phenomenon.},
Doi = {10.1073/pnas.0502893102},
Key = {fds268455}
}
@article{fds268346,
Author = {Howe, CQ and Purves, D},
Title = {Perceiving geometry: Geometrical illusions explained by
natural scene statistics},
Journal = {Perceiving Geometry: Geometrical Illusions Explained by
Natural Scene Statistics},
Pages = {1-126},
Publisher = {Springer Verlag},
Year = {2005},
Month = {January},
url = {http://dx.doi.org/10.1007/b135453},
Abstract = {Understanding vision, whether from a neurobiological,
psychological or philosophical perspective, represents a
daunting challenge that has been pursued for millennia.
During at least the last few centuries, natural
philosophers, and more recently vision scientists, have
recognized that a fundamental problem in biological vision
is that the physical sources underlying sensory stimuli are
unknowable in any direct sense. In vision, because physical
qualities are conflated when the 3-D world is projected onto
the 2-D image plane of the retina, the provenance of light
reaching the eye at any moment is inevitably uncertain. This
quandary is referred to as the inverse optics problem. The
relationship of the real world and the information conveyed
to the brain by light present a profound problem. Successful
behavior in a complex and potentially hostile environment
clearly depends on responding appropriately to the sources
of visual stimuli rather than to the physical
characteristics of the stimuli as such. If the retinal
images generated by light cannot specify the underlying
reality an observer must deal with, how then does the visual
system produce behavior that is generally successful?
Perceiving Geometry considers the evidence that, with
respect to the perception of geometry, the human visual
system solves this problem by incorporating past human
experience of what retinal images have typically
corresponded to in the real world. This empirical strategy,
which is documented by extensive analyses of scene geometry,
explains many otherwise puzzling aspects of what we see
(i.e., the so-called "geometrical illusions"), providing the
best indication to date as to how perceptions of the
geometrical aspects of the world are actually generated by
the brain.},
Doi = {10.1007/b135453},
Key = {fds268346}
}
@article{fds268453,
Author = {Howe, CQ and Purves, D},
Title = {The Müller-Lyer illusion explained by the statistics of
image-source relationships.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {102},
Number = {4},
Pages = {1234-1239},
Year = {2005},
Month = {January},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/15657142},
Abstract = {The Müller-Lyer effect, the apparent difference in the
length of a line as the result of its adornment with
arrowheads or arrow tails, is the best known and most
controversial of the classical geometrical illusions. By
sampling a range-image database of natural scenes, we show
that the perceptual effects elicited by the Müller-Lyer
stimulus and its major variants are correctly predicted by
the probability distributions of the possible physical
sources underlying the relevant retinal images. These
results support the conclusion that the Müller-Lyer
illusion is a manifestation of the probabilistic strategy of
visual processing that has evolved to contend with the
uncertain provenance of retinal stimuli.},
Doi = {10.1073/pnas.0409314102},
Key = {fds268453}
}
@article{fds268456,
Author = {Howe, CQ and Purves, D},
Title = {Natural-scene geometry predicts the perception of angles and
line orientation.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {102},
Number = {4},
Pages = {1228-1233},
Year = {2005},
Month = {January},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/15657143},
Abstract = {Visual stimuli that entail the intersection of two or more
straight lines elicit a variety of well known perceptual
anomalies. Preeminent among these anomalies are the
systematic overestimation of acute angles, the
underestimation of obtuse angles, and the misperceptions of
line orientation exemplified in the classical tilt, Zollner,
and Hering illusions. Here we show that the probability
distributions of the possible real-world sources of
projected lines and angles derived from a range-image
database of natural scenes accurately predict each of these
perceptual peculiarities. These findings imply that the
perception of angles and oriented lines is determined by the
statistical relationship between geometrical stimuli and
their physical sources in typical visual
environments.},
Doi = {10.1073/pnas.0409311102},
Key = {fds268456}
}
@article{fds114100,
Title = {Lotto RB, Purves D (2005) Understanding the basis of color
perception. International Review of Neurobiology (In
press).},
Year = {2005},
Key = {fds114100}
}
@article{fds268452,
Author = {Schwartz, DA and Purves, D},
Title = {Pitch is determined by naturally occurring periodic
sounds.},
Journal = {Hearing Research},
Volume = {194},
Number = {1-2},
Pages = {31-46},
Year = {2004},
Month = {August},
ISSN = {0378-5955},
url = {http://www.ncbi.nlm.nih.gov/pubmed/15276674},
Abstract = {The phenomenology of pitch has been difficult to rationalize
and remains the subject of much debate. Here we test the
hypothesis that audition generates pitch percepts by
relating inherently ambiguous sound stimuli to their
probable sources in the human auditory environment. A
database of speech sounds, the principal source of periodic
sound energy for human listeners, was compiled and the
dominant periodicity of each speech sound determined. A set
of synthetic test stimuli were used to assess whether the
major pitch phenomena described in the literature could be
explained by the probabilistic relationship between the
stimuli and their probable sources (i.e., speech sounds).
The phenomena tested included the perception of the missing
fundamental, the pitch-shift of the residue, spectral
dominance and the perception of pitch strength. In each
case, the conditional probability distribution of speech
sound periodicities accurately predicted the pitches
normally heard in response to the test stimuli. We conclude
from these findings that pitch entails an auditory process
that relates inevitably ambiguous sound stimuli to their
probable natural sources.},
Doi = {10.1016/j.heares.2004.01.019},
Key = {fds268452}
}
@article{fds268454,
Author = {Yang, Z and Purves, D},
Title = {The statistical structure of natural light patterns
determines perceived light intensity.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {101},
Number = {23},
Pages = {8745-8750},
Year = {2004},
Month = {June},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/15152077},
Abstract = {The same target luminance in different contexts can elicit
markedly different perceptions of brightness, a fact that
has long puzzled vision scientists. Here we test the
proposal that the visual system encodes not luminance as
such but rather the statistical relationship of a particular
luminance to all possible luminance values experienced in
natural contexts during evolution. This statistical
conception of vision was validated by using a database of
natural scenes in which we could determine the probability
distribution functions of co-occurring target and contextual
luminance values. The distribution functions obtained in
this way predict target brightness in response to a variety
of challenging stimuli, thus explaining these otherwise
puzzling percepts. That brightness is determined by the
statistics of natural light patterns implies that the
relevant neural circuitry is specifically organized to
generate these probabilistic responses.},
Doi = {10.1073/pnas.0402192101},
Key = {fds268454}
}
@article{fds268447,
Author = {Purves, D and Williams, SM and Nundy, S and Lotto,
RB},
Title = {Perceiving the intensity of light.},
Journal = {Psychological Review},
Volume = {111},
Number = {1},
Pages = {142-158},
Year = {2004},
Month = {January},
ISSN = {0033-295X},
url = {http://www.ncbi.nlm.nih.gov/pubmed/14756591},
Abstract = {The relationship between luminance (i.e., the photometric
intensity of light) and its perception (i.e., sensations of
lightness or brightness) has long been a puzzle. In addition
to the mystery of why these perceptual qualities do not
scale with luminance in any simple way, "illusions" such as
simultaneous brightness contrast, Mach bands,
Craik-O'Brien-Cornsweet edge effects, and the
Chubb-Sperling-Solomon illusion have all generated much
interest but no generally accepted explanation. The authors
review evidence that the full range of this perceptual
phenomenology can be rationalized in terms of an empirical
theory of vision. The implication of these observations is
that perceptions of lightness and brightness are generated
according to the probability distributions of the possible
sources of luminance values in stimuli that are inevitably
ambiguous.},
Doi = {10.1037/0033-295x.111.1.142},
Key = {fds268447}
}
@article{fds268450,
Author = {Howe, CQ and Purves, D},
Title = {Size contrast and assimilation explained by the statistics
of natural scene geometry.},
Journal = {Journal of Cognitive Neuroscience},
Volume = {16},
Number = {1},
Pages = {90-102},
Year = {2004},
Month = {January},
ISSN = {0898-929X},
url = {http://www.ncbi.nlm.nih.gov/pubmed/15006039},
Abstract = {The term "size contrast and assimilation" refers to a large
class of geometrical illusions in which the apparent sizes
of identical visual targets in various contexts are
different. Here we have examined whether these intriguing
discrepancies between physical and perceived size can be
explained by a visual process in which percepts are
determined by the probability distribution of the possible
real-world sources of retinal stimuli. To test this idea, we
acquired a range image database of natural scenes that
specified the location of every image point in 3-D space. By
sampling the possible physical sources of various size
contrast or assimilation stimuli in the database, we
determined the probability distributions of the size of the
target in the images generated by these sources. For each of
the various stimuli tested, these probability distributions
of target size in different contexts accurately predicted
the perceptual effects reported in psychophysical studies.
We conclude that size contrast and assimilation effects are
a further manifestation of a fundamentally probabilistic
process of visual perception.},
Doi = {10.1162/089892904322755584},
Key = {fds268450}
}
@article{fds268451,
Author = {Lotto, RB and Purves, D},
Title = {Perceiving colour},
Journal = {Review of Progress in Coloration and Related
Topics},
Volume = {34},
Number = {1},
Pages = {12-25},
Publisher = {WILEY},
Year = {2004},
Month = {January},
ISSN = {0557-9325},
url = {http://dx.doi.org/10.1111/j.1478-4408.2004.tb00149.x},
Abstract = {Understanding the percepts elicited by spectral
distributions in visual stimuli (i.e. understanding the
perception of colour) is made especially challenging by the
peculiar phenomenology of colour contrast and constancy
effects. Interestingly as the first systematic account of
colour contrast was published in 1839 by the French chemist
Michel Chevreul based on work done while serving as the
director of dyes for the Royal Manufacturers. In this
current paper we review the nature of colour vision, the
problems that the observations of Chevreul and others
present for colour science, and recent work that suggests a
solution. © Rev. Prog. Color.},
Doi = {10.1111/j.1478-4408.2004.tb00149.x},
Key = {fds268451}
}
@article{fds114060,
Title = {Purves, D., S.M. Williams, S. Nundy and B.B. Lotto (2003)
Perceiving the Intensity of Light. Psychological Rev. Vol
111: 142-158.},
Year = {2004},
Key = {fds114060}
}
@article{fds114066,
Title = {Howe Q, Purves D (2004) Size contrast and assimilation
explained by the statistics of scene geometry. J Cog
Neurosci 16(1): 90-102.},
Year = {2004},
Key = {fds114066}
}
@article{fds114099,
Title = {Purves D, Lotto RB (2004) The Cornsweet effect. Encyclopedia
of Neuroscience, 3rd edition. G. Adelman and B.H. Smith,
eds. Elsevier Press 2004.},
Year = {2004},
Key = {fds114099}
}
@article{fds114101,
Title = {Lotto RB, Purves D (2004) Perceiving color. Color Dyers Rev
(in press).},
Year = {2004},
Key = {fds114101}
}
@article{fds114102,
Title = {Yang Z, Purves D (2004) The statistical structure of natural
light patterns determines perceived light intensity. Proc
Natl Acad Sci 101: 8745-8750},
Year = {2004},
Key = {fds114102}
}
@article{fds114103,
Title = {Schwartz D, Purves D (2004) Pitch is determined by naturally
occurring periodic sounds. Hearing Research 194:
31-46.},
Year = {2004},
Key = {fds114103}
}
@article{fds268442,
Author = {Long, F and Purves, D},
Title = {Evidence that color contrast effects have a probabilistic
foundation},
Journal = {Journal of Vision},
Volume = {3},
Number = {9},
Pages = {314-314},
Publisher = {Association for Research in Vision and Ophthalmology
(ARVO)},
Year = {2003},
Month = {December},
url = {http://dx.doi.org/10.1167/3.9.314},
Abstract = {Surfaces returning identical light spectra to the eye can
elicit different color percepts when embedded in spectrally
different surrounds. Although various theories have been put
forward to rationalize these color contrast effects, there
is no consensus about their basis. Here we tested the
hypothesis that color contrast is generated by the
probability distribution of the possible physical sources of
spectral stimuli (see Lotto and Purves, PNAS 97:12834,
2001). The analysis used a database of 41 natural scenes in
which the radiance spectrum of each point (i.e., the
projected light spectrum for each pixel in the images) was
known. The relevant reflectance spectra for corresponding
points were computed by removing the influence of both the
illuminant and scene geometry from the radiance spectrum.
The illumination spectra for each pixel (which include the
influence of both the illuminant and scene geometry) were
then determined by dividing the radiance spectrum by
reflectance spectrum. To facilitate the statistical
analysis, the radiance spectrum on each pixel was converted
into RGB tristimulus values. Each image in the database was
sampled repeatedly with a center/surround template, and the
probability distributions of the possible combinations of
reflectance and illumination spectra that could have
generated the relevant RGB values were determined. The
probability distributions of the reflectance and
illumination spectra of the central target varied as a
function of the RGB values of the surround, indicating that
the typical physical sources of target spectra differ when
they are embedded in spectrally different surrounds. The
color percepts predicted by these distributions were in good
agreement with the percepts elicited by color contrast
stimuli. This evidence supports the conclusion that color
contrast effects are determined by the probabilistic
relationship between ambiguous spectral stimuli and the
distribution of their possible sources.},
Doi = {10.1167/3.9.314},
Key = {fds268442}
}
@article{fds268443,
Author = {Purves, D and Howe, CQ and Schwartz, DA},
Title = {Vision and the perception of music have a common
denominator},
Journal = {Journal of Vision},
Volume = {3},
Number = {9},
Pages = {518-518},
Publisher = {Association for Research in Vision and Ophthalmology
(ARVO)},
Year = {2003},
Month = {December},
url = {http://dx.doi.org/10.1167/3.9.518},
Abstract = {All human listeners perceive tones in the presence of
regularly repeating patterns of sound pressure fluctuation
over a wide range of frequencies. In music, the salient and
widely-shared features of this aspect of auditory perception
are: 1) an iterated partitioning of the continuous dimension
of pitch into octave intervals bounded by tones that are
musically similar; 2) the division of each octave into the
12 intervals of the chromatic scale; 3) the preference in
musical composition and performance for particular subsets
of these 12 intervals (e.g., the intervals of the pentatonic
or diatonic scales); and 4) the similar consonance ordering
of chromatic scale tone combinations produced by listeners
of all ages, places, and periods. Despite intense interest
in these perceptual phenomena over several millennia, they
have no generally accepted explanation in physical,
psychological or biological terms. A rapidly growing body of
work in vision has shown that the fundamental qualities that
characterize visual percepts (lightness/brightness, color,
geometry and motion) accord with the probability
distributions of the possible sources of visual stimuli.
Since the uncertain provenance of sensory stimuli is
general, this empirical solution to the inverse optics
problem might be expected to extend to other sensory
modalities. We therefore examined the hypothesis that
musical percepts also arise from the statistical
relationship between sound stimuli and their natural
sources. An analysis of recorded speech shows that the
probability distribution of amplitude/frequency combinations
in human utterances, the principal source of periodic
stimuli in the human acoustical environment, predicts
octaves, scales and consonance. These observations suggest
that the auditory system, like the visual system, generates
percepts determined by the probability distributions that
link inherently ambiguous stimuli and their
sources.},
Doi = {10.1167/3.9.518},
Key = {fds268443}
}
@article{fds268444,
Author = {Howe, CQ and Purves, D},
Title = {Size contrast explained by the statistics of scene
geometry},
Journal = {Journal of Vision},
Volume = {3},
Number = {9},
Pages = {522-522},
Publisher = {Association for Research in Vision and Ophthalmology
(ARVO)},
Year = {2003},
Month = {December},
url = {http://dx.doi.org/10.1167/3.9.522},
Abstract = {Standard presentations of size contrast stimuli include the
well-known Ebbinghaus circles and the Delboeuf figures. When
presented with such stimuli, observers perceive a target
form surrounded by larger but otherwise similar forms to be
smaller than the same target surrounded by smaller forms.
Here we have examined the hypothesis that the anomalous
perception of these stimuli is a consequence of a wholly
probabilistic strategy of vision in which percepts accord
with the probability distribution of the possible sources of
the stimuli. To test this idea, we used a range image
database acquired by laser scanning natural scenes to
determine the probability distribution of the size of the
real-world sources of the central targets in the size
contrast stimuli. In good quantitative agreement with a
large body of psychophysical evidence, the average physical
size of the sources of a given form embedded in a context of
larger surrounding forms in the image plane is smaller than
the sources of the same target surrounded by smaller forms.
Thus, the reason why the two identical central targets look
different in size is because their possible physical sources
are, in fact, different in size. These findings support the
hypothesis that the size contrast effect is a signature of a
fundamentally probabilistic process of vision
perception.},
Doi = {10.1167/3.9.522},
Key = {fds268444}
}
@article{fds268445,
Author = {Yang, Z and Purves, D},
Title = {Statistical concatenations of luminance can explain
lightness/brightness percepts},
Journal = {Journal of Vision},
Volume = {3},
Number = {9},
Pages = {423-423},
Publisher = {Association for Research in Vision and Ophthalmology
(ARVO)},
Year = {2003},
Month = {December},
url = {http://dx.doi.org/10.1167/3.9.423},
Abstract = {A number of recent studies have indicated that perceptions
of lightness/brightness are determined by the probabilistic
relationship between the luminances in the retinal stimulus
and the possible physical sources (reviewed in Purves and
Lotto, "Why we see what we do" Sinauer, 2002). To date,
these analyses have relied primarily on qualitative
paradigms, or limited quantitative arguments to rationalize
the lightness/brightness percepts elicited by Cornsweet
edges, stimuli that elicit Mach bands, or the reduced cue
conditions used in brightness scaling experiments.
Considering the linkage between stimulus luminances and
lightness/brightness percepts more broadly, however, the
visual system must instantiate a more fundamental set of
underlying statistical relationships to generate
lightness/brightness percepts in any and all circumstances.
Given the high dimensionality of real-world effects on the
probability distribution of lightness/brightness sources, it
seems inevitable that the relevant statistical
instantiations entail the conditional probabilities of
concatenations of luminance values in retinal images with
respect to the underlying natural sources. Accordingly, we
have explored whether anomalies of lightness/brightness can
be explained in these terms by analyzing the distribution of
luminance in 4200 images of natural visual environments in
the so-called Netherlands database (hlab.phys.rug.nl). A
large number of samples were generated using various
templates in which the pattern of light was similar to the
basic unit in several well-known lightness/brightness
stimuli that generate unusual percepts (e.g., the Hermann
grid, the Wertheimer-Benary pattern, White's stimulus and
the criss-cross pattern), thus allowing us to compute the
probability distribution of light in the 'target' area of
these stimuli. The relative shifts in the probability
distributions of luminance in these stimuli appear to
account for the associated perceptions of
lightness/brightness.},
Doi = {10.1167/3.9.423},
Key = {fds268445}
}
@article{fds268449,
Author = {Long, F and Purves, D},
Title = {Natural scene statistics as the universal basis of color
context effects.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {100},
Number = {25},
Pages = {15190-15193},
Year = {2003},
Month = {December},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/14623975},
Abstract = {The color context effects referred to as color contrast,
constancy, and assimilation underscore the fact that color
percepts do not correspond to the spectral characteristics
of the generative stimuli. Despite a variety of proposed
theories, these phenomena have resisted explanation in a
single principled framework. Using a hyperspectral image
database of natural scenes, we here show that color
contrast, constancy, and assimilation are all predicted by
the statistical organization of spectral returns from
natural visual environments.},
Doi = {10.1073/pnas.2036361100},
Key = {fds268449}
}
@article{fds268446,
Author = {Yang, Z and Purves, D},
Title = {Image/source statistics of surfaces in natural
scenes.},
Journal = {Network: Computation in Neural Systems},
Volume = {14},
Number = {3},
Pages = {371-390},
Year = {2003},
Month = {August},
ISSN = {0954-898X},
url = {http://www.ncbi.nlm.nih.gov/pubmed/12938763},
Abstract = {Perceiving surfaces in a manner that accords with their
physical properties is essential for successful behaviour.
Since, however, a given retinal image can have been
generated by an infinite variety of natural surfaces with
different geometrical and/or physical qualities, the
corresponding percepts cannot be determined by the stimulus
per se. Rather, resolution of this quandary requires a
strategy of vision that incorporates the statistical
relationship of the information in retinal images to its
sources in representative environments. To examine this
probabilistic relationship with respect to the features of
object surfaces, we analysed a database of range images in
which the distances of all the objects in a series of
natural scenes were measured with respect to the image plane
by a laser range scanner. By taking any particular scene
obtained in this way to be made up of a set of concatenated
surface patches, we were able to explore the statistics of
scene roughness, size-distance relationships, surface
orientation and local curvature, as well as the independent
components of natural surfaces. The relevance of these
statistics to both perception and the neuronal organization
of the underlying visual circuitry is discussed.},
Doi = {10.1088/0954-898x_14_3_301},
Key = {fds268446}
}
@article{fds268448,
Author = {Schwartz, DA and Howe, CQ and Purves, D},
Title = {The statistical structure of human speech sounds predicts
musical universals.},
Journal = {The Journal of Neuroscience : the Official Journal of the
Society for Neuroscience},
Volume = {23},
Number = {18},
Pages = {7160-7168},
Year = {2003},
Month = {August},
url = {http://www.ncbi.nlm.nih.gov/pubmed/12904476},
Abstract = {The similarity of musical scales and consonance judgments
across human populations has no generally accepted
explanation. Here we present evidence that these aspects of
auditory perception arise from the statistical structure of
naturally occurring periodic sound stimuli. An analysis of
speech sounds, the principal source of periodic sound
stimuli in the human acoustical environment, shows that the
probability distribution of amplitude-frequency combinations
in human utterances predicts both the structure of the
chromatic scale and consonance ordering. These observations
suggest that what we hear is determined by the statistical
relationship between acoustical stimuli and their naturally
occurring sources, rather than by the physical parameters of
the stimulus per se.},
Doi = {10.1523/jneurosci.23-18-07160.2003},
Key = {fds268448}
}
@article{fds268501,
Author = {Yang, Z and Purves, D},
Title = {A statistical explanation of visual space.},
Journal = {Nature Neuroscience},
Volume = {6},
Number = {6},
Pages = {632-640},
Year = {2003},
Month = {June},
ISSN = {1097-6256},
url = {http://www.ncbi.nlm.nih.gov/pubmed/12754512},
Keywords = {Humans • Models, Neurological • Models,
Statistical* • Photic Stimulation • Psychomotor
Performance • Space Perception • Spatial Behavior
• Visual Fields • physiology*},
Abstract = {The subjective visual space perceived by humans does not
reflect a simple transformation of objective physical space;
rather, perceived space has an idiosyncratic relationship
with the real world. To date, there is no consensus about
either the genesis of perceived visual space or the
implications of its peculiar characteristics for visually
guided behavior. Here we used laser range scanning to
measure the actual distances from the image plane of all
unoccluded points in a series of natural scenes. We then
asked whether the differences between real and apparent
distances could be explained by the statistical relationship
of scene geometry and the observer. We were able to predict
perceived distances in a variety of circumstances from the
probability distribution of physical distances. This finding
lends support to the idea that the characteristics of human
visual space are determined probabilistically.},
Language = {eng},
Doi = {10.1038/nn1059},
Key = {fds268501}
}
@article{fds114062,
Title = {Yang, Z. and D. Purves (2003) Image/source statistics in
natural scenes. Network: Computation in Neural Systems 14
(3): 371-390.},
Year = {2003},
Key = {fds114062}
}
@article{fds114063,
Title = {Schwartz, D., C.Q. Howe and D. Purves (2003) Statistical
evidence that musical universals derive from the acoustical
characteristics of human speech. J. Neurosci. 23:
7160-7168.},
Year = {2003},
Key = {fds114063}
}
@article{fds114092,
Title = {Long, F. and D. Purves (2003) Natural scene statistics as
the universal basis for color context effects. Proc Natl
Acad Sci 100 (25): 15190-15193.},
Year = {2003},
Key = {fds114092}
}
@article{fds114095,
Title = {Purves, D. and R.B. Lotto (2003) Why We See What We Do:
An Empirical Theory of Vision. Sinauer Associates:
Sunderland, MA.},
Year = {2003},
Key = {fds114095}
}
@article{fds268438,
Author = {Purves, D and Yang, Z},
Title = {The Poggendorff illusion explained by the statistics of
natural scene geometry},
Journal = {Journal of Vision},
Volume = {2},
Number = {7},
Pages = {201-201},
Publisher = {Association for Research in Vision and Ophthalmology
(ARVO)},
Year = {2002},
Month = {December},
url = {http://dx.doi.org/10.1167/2.7.201},
Abstract = {One of the most intriguing discrepancies between the
perception of a visual stimulus and its real-world source is
the Poggendorff illusion. When an obliquely oriented line is
occluded by a bar, the continuation of the line across the
occluder appears to be shifted vertically, despite of the
collinearity of the separated line segments. A great deal of
literature on this subject notwithstanding, none of the
explanations so far provided (the angle theory and the depth
theory are the two major categories) has satisfactorily
accounted for all aspects of this effect. Here we have
tested a wholly empirical explanation of this illusion. To
this end, we acquired a database of natural scenes
(including indoor, outdoor and natural scenes) in which the
distances of all the objects from the image plane were
determined with a laser range scanner. We found the
probability distribution of the possible positions of the
line segments in the database lying on the 'far side' of an
imagined occluder to be shifted vertically compared to the
positions obtained by direct extension of the same line
segments. This shift was apparent in indoor, outdoor and
fully natural scenes, albeit with different magnitudes and
variances. Moreover, the magnitude of the shift 1) increased
with the width of the occluding bar; 2) increased with a
decrease in the (acute) angle of the intersection of the
line with the occluder; 3) diminished for the acute angle
components of the stimulus, but was maintained for the
obtuse angle components; and 4) diminished when the stimulus
configuration was rotated. Each of these behaviors has been
described in the perceptual responses to corresponding
variations in the presentation of the Poggendorff stimulus.
We conclude that this otherwise peculiar set of perceptual
discrepancies is generated by the probabilistic relationship
between the relevant features in the image plane and the
probability distribution of the possible underlying sources
of the stimulus in the real world.},
Doi = {10.1167/2.7.201},
Key = {fds268438}
}
@article{fds268439,
Author = {Howe, CQ and Purves, D},
Title = {A probabilistic explanation of perceived line length and
orientation},
Journal = {Journal of Vision},
Volume = {2},
Number = {7},
Pages = {706-706},
Publisher = {Association for Research in Vision and Ophthalmology
(ARVO)},
Year = {2002},
Month = {December},
url = {http://dx.doi.org/10.1167/2.7.706},
Abstract = {Human perception of the length and the orientation of a
straight line is systematically biased as a function of the
2D orientation of the line in the retinal image. Motivated
by recent evidence that the relationship between the retinal
image and perception is a wholly probabilistic one, we have
explored the idea that perceived length and orientation of a
linear stimulus are determined by the probabilistic
relationship between the linear projection in the image
plane and its possible physical sources. To test this
hypothesis, we collected a database of natural scenes that
included the range and luminance of every pixel in the
images. The database thus relates projections in the image
plane to the arrangement of objects in the physical world.
Accordingly, we could determine the 3-D orientations of the
physical sources of all straight-line projections on the
retina (the image plane), as well as the ratio of the
physical length of the sources to the length of their
projections. We found that the probability distributions of
the tilt, slant and the physical-to-image length ratio of
straight lines determined in this way change systematically
as a function of the orientation of the projected line.
These variations in the probability distributions predict
the perception of line length and line orientation as a
function of line orientation. Because the probability
distributions of the possible sources of oblique projections
show greater variance than those of the linear projections
in the cardinal axes, these statistical relationships can
also rationalize the oblique effect (i.e., the poorer and
more variable performance of human observers confronted with
oblique lines compared to performance with lines in the
cardinal axes).},
Doi = {10.1167/2.7.706},
Key = {fds268439}
}
@article{fds268440,
Author = {Yang, Z and Purves, D},
Title = {The probabilistic foundation of visual space},
Journal = {Journal of Vision},
Volume = {2},
Number = {7},
Pages = {715-715},
Publisher = {Association for Research in Vision and Ophthalmology
(ARVO)},
Year = {2002},
Month = {December},
url = {http://dx.doi.org/10.1167/2.7.715},
Abstract = {An assumption in many studies is that visual space (i.e.,
the space we perceive) is metrical. For example, perceived
space has often been considered a Riemann space of constant
curvature. In such cases, perceived spatial relationships
should be independent of the context of the visual scene.
This category of assumptions, however, is inconsistent with
numerous experimental observations showing that the
relationship between the perceived and the physical
parameters of scene geometry is systematically distorted. In
the absence of a principled account of what this distortion
of physical space actually means, other investigators have
assumed that visual space is either affine or subject to
some other transformation of physical space. Here we have
explored an alternative hypothesis, namely that visual space
is generated solely by the statistical properties of the
physical world. To this end, we acquired and analyzed a
database of natural scenes in which the distances of all
object points from the image plane were measured with a
laser range scanner. The probability distributions of these
distances are scale invariant, a feature that accords with
the human perception of distance and location under
impoverished stimulus conditions. Furthermore, the
probability distributions of the physical sources of visual
stimuli (i.e., their distance, depth, size, and surface
orientation) were found to be systematically influenced by
the range distribution of the surround. These
context-dependent probability distributions of physical
sources generally account for the known distortion in the
perception of distance, depth, size, and orientation (e.g.,
the "terrain influence" on distance judgment, and the
well-known contextual effects that influence the perception
of orientation). Our results thus suggest that visual
perceptual space, for reasons of biological advantage, is
straightforwardly determined by the probability
distributions of the sources underlying visual
stimuli.},
Doi = {10.1167/2.7.715},
Key = {fds268440}
}
@article{fds268441,
Author = {Long, F and Purves, D},
Title = {A probabilistic explanation of simultaneous brightness
contrast},
Journal = {Journal of Vision},
Volume = {2},
Number = {7},
Pages = {366-366},
Publisher = {Association for Research in Vision and Ophthalmology
(ARVO)},
Year = {2002},
Month = {December},
url = {http://dx.doi.org/10.1167/2.7.366},
Abstract = {A growing body of evidence suggests that visual perception
is generated according to the probabilistic relationship
between the components of retinal images and their possible
physical sources. We have further explored this idea by
asking whether simultaneous brightness contrast effects can
be explained by the statistical relationship between the
physical sources of the light reaching the retina and the
corresponding luminance values in the retinal image. To this
end we first created a database of spectral returns
(radiances) based on the interaction of average daylight
(CIE D65) at 500 different levels of light intensity with
200 achromatic reflectances (interpolated from 6 standard
achromatic reflectances of Macbeth ColorChecker). A database
of luminances was then created by converting each of the
100,000 spectral returns obtained in this way into an RGB
value using the standard CIE conversion. We then used the
luminance database to create standard and 'articulated'
brightness contrast stimuli. An analysis of the probability
distributions of the possible illumination and reflectance
values that could have generated the stimuli showed that: 1)
the illumination of a gray patch with a dark surround is
likely to be less intense than the illumination of the same
patch in a lighter surround; 2) the illumination difference
of gray patches in uniform surrounds is likely to be less
than the illumination difference of the same patches in
articulated surrounds. Thus on solely empirical grounds,
these probability distributions predict that a gray patch
with a darker surround will look brighter than the same
patch on a lighter surround, and that the articulated
version will generate a stronger perceptual effect. The
significance of this work is to demonstrate that the effects
of standard brightness contrast stimuli can be rationalized
on the basis of the probability distributions of the sources
derived from a contrived but nevertheless plausible database
of visual 'scenes'.},
Doi = {10.1167/2.7.366},
Key = {fds268441}
}
@article{fds268498,
Author = {Lotto, RB and Purves, D},
Title = {The empirical basis of color perception.},
Journal = {Consciousness and Cognition},
Volume = {11},
Number = {4},
Pages = {609-629},
Year = {2002},
Month = {December},
ISSN = {1053-8100},
url = {http://www.ncbi.nlm.nih.gov/pubmed/12470626},
Keywords = {Color Perception • Humans • Light • Photic
Stimulation • Probability* • physiology*},
Abstract = {Rationalizing the perceptual effects of spectral stimuli has
been a major challenge in vision science for at least the
last 200 years. Here we review evidence that this otherwise
puzzling body of phenomenology is generated by an empirical
strategy of perception in which the color an observer sees
is entirely determined by the probability distribution of
the possible sources of the stimulus. The rationale for this
strategy in color vision, as in other visual perceptual
domains, is the inherent ambiguity of the real-world origins
of any spectral stimulus.},
Doi = {10.1016/s1053-8100(02)00014-4},
Key = {fds268498}
}
@article{fds268500,
Author = {Howe, CQ and Purves, D},
Title = {Range image statistics can explain the anomalous perception
of length.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {99},
Number = {20},
Pages = {13184-13188},
Year = {2002},
Month = {October},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/12237401},
Keywords = {Humans • Lasers • Retina • Space Perception
• Vision • Visual Perception* • physiology
• physiology*},
Abstract = {A long-standing puzzle in visual perception is that the
apparent extent of a spatial interval (e.g., the distance
between two points or the length of a line) does not simply
accord with the length of the stimulus but varies as a
function of orientation in the retinal image. Here, we show
that this anomaly can be explained by the statistical
relationship between the length of retinal projections and
the length of their real-world sources. Using a laser range
scanner, we acquired a database of natural images that
included the three-dimensional location of every point in
the scenes. An analysis of these range images showed that
the average length of a physical interval in
three-dimensional space changes systematically as a function
of the orientation of the corresponding interval in the
projected image, the variation being in good agreement with
perceived length. This evidence implies that the perception
of visual space is determined by the probability
distribution of the possible real-world sources of retinal
images.},
Doi = {10.1073/pnas.162474299},
Key = {fds268500}
}
@article{fds268502,
Author = {Nundy, S and Purves, D},
Title = {A probabilistic explanation of brightness
scaling.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {99},
Number = {22},
Pages = {14482-14487},
Year = {2002},
Month = {October},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/12388786},
Keywords = {Computer Simulation* • Humans • Light •
Models, Neurological* • Models, Statistical* •
Photic Stimulation • Visual Perception •
physiology*},
Abstract = {The perceptions of lightness or brightness elicited by a
visual target are linked to its luminance by a nonlinear
function that varies according to the physical
characteristics of the target and the background on which it
is presented. Although no generally accepted explanation of
this scaling relationship exists, it has long been
considered a byproduct of low- or mid-level visual
processing. Here we examine the possibility that brightness
scaling is actually the signature of a biological strategy
for dealing with inevitably ambiguous visual stimuli, in
which percepts of lightness/brightness are determined by the
probabilistic relationship between luminances in the image
plane and their possible real-world sources.},
Doi = {10.1073/pnas.172520399},
Key = {fds268502}
}
@article{fds268499,
Author = {Lotto, RB and Purves, D},
Title = {A rationale for the structure of color space.},
Journal = {Trends in Neurosciences},
Volume = {25},
Number = {2},
Pages = {84-88},
Year = {2002},
Month = {February},
ISSN = {0166-2236},
url = {http://www.ncbi.nlm.nih.gov/pubmed/11814560},
Keywords = {Animals • Color • Color Perception • Humans
• Light • Photic Stimulation •
physiology*},
Abstract = {The colors perceived by humans in response to light stimuli
are generally described in terms of four color categories
(reds, greens, blues and yellows), the members of which are
systematically arrayed around gray. This broadly accepted
description of color sensation differs fundamentally from
the light that induces it, which is neither 'circular' nor
categorical. What, then, accounts for these discrepancies
between the structure of color experience and the physical
reality that underlies it? We suggest that these differences
are based on two related requirements for successful color
vision: (1) that spectra be ordered according to their
physical similarities and differences; and (2) that this
ordering be constrained by the four-color map
problem.},
Doi = {10.1016/s0166-2236(02)02059-3},
Key = {fds268499}
}
@article{fds268497,
Author = {Yang, Z and Shimpi, A and Purves, D},
Title = {Perception of objects that are translating and
rotating.},
Journal = {Perception},
Volume = {31},
Number = {8},
Pages = {925-942},
Year = {2002},
Month = {January},
ISSN = {0301-0066},
url = {http://www.ncbi.nlm.nih.gov/pubmed/12269587},
Keywords = {Discrimination Learning • Form Perception • Humans
• Motion • Motion Perception • Psychophysics
• Rotation • physiology*},
Abstract = {The motion of objects that are both translating and rotating
can be decomposed into an infinite number of translational
and rotational combinations. How, then, do such stimuli
routinely elicit specific percepts and behavioral responses
that are usually appropriate? A possible answer is that
motion percepts are fully determined by the probability
distributions of all the possible correspondences and
differences in the stimulus sequence. To test the merits of
this conceptual framework, we investigated the perceived
motion elicited by a line that is both translating and
rotating behind an aperture. When stimuli are presented such
that a particular sequence of appearance and disappearance
occurs at the aperture boundary, subjects report that the
line is rotating only; furthermore, the perceived centers of
rotation appear to describe a cycloidal trajectory, even
when one aperture shape is replaced by another. These and
other perceptual effects elicited by translating and
rotating stimuli are all accurately predicted by the
probability distribution of the possible sources of the
physical movements, supporting the conclusion that motion
perception is indeed generated by a wholly probabilistic
strategy.},
Doi = {10.1068/p3379},
Key = {fds268497}
}
@article{fds114059,
Title = {Lotto, R.B and D. Purves (2002) An empirical explanation of
the Chubb Illusion. J. Cog. Neurosci. 13:
1-9.},
Year = {2002},
Key = {fds114059}
}
@article{fds114094,
Title = {Purves D., R. B. Lotto and S. Nundy (2002) Why we see what
we do. American Scientist 90(3): 236-243.},
Year = {2002},
Key = {fds114094}
}
@article{fds268431,
Author = {Purves, D and Lotto, B},
Title = {Explanation of some major features of color
perception},
Journal = {Journal of Vision},
Volume = {1},
Number = {3},
Pages = {60-60},
Publisher = {Association for Research in Vision and Ophthalmology
(ARVO)},
Year = {2001},
Month = {December},
url = {http://dx.doi.org/10.1167/1.3.60},
Abstract = {It has long been known that a particular red, green, blue
and yellow is seen as being entirely free of any other
color, and that the four color categories defined in this
way are arranged in a circular manner. Most textbook
accounts suppose that these features of color experience are
an incidental consequence of color opponency. An alternative
possibility is that these aspects of color experience
represent the solution of a fundamental problem in topology,
namely insuring that no two areas separated by a common
boundary in a 2-dimensional array will appear the same if
they are actually different (the four color map problem).
However, unlike the cartographer, whose task is simply to
distinguish the surfaces in a map as being the 'same' or
'different', the visual system must distinguish surfaces and
at the same time maintain the full range of spectral
relationships. Simply differentiating surfaces in color
experience would provide little behavioral advantage if the
relative similarities and differences among different
spectra were not also preserved in perception. If this
argument is correct, then structure of subjective color
space (i.e., the circular organization of the four color
categories and their unique members), should reflect an
analogous ordering of spectra. Here we use multidimensional
scaling of a spectral data set to show that arranging
spectra according to their relative similarities and
differences defines a space that is similar to subjective
color space. These results are consistent with the
conclusion that the major features of subjective color
experience represent a simultaneous solution of the four
color map problem while maintaining the relative
similarities and differences among the full range of light
spectra.},
Doi = {10.1167/1.3.60},
Key = {fds268431}
}
@article{fds268432,
Author = {Lotto, RB and Purves, D},
Title = {An empirical explanation of the Chubb illusion},
Journal = {Journal of Vision},
Volume = {1},
Number = {3},
Pages = {48-48},
Publisher = {Association for Research in Vision and Ophthalmology
(ARVO)},
Year = {2001},
Month = {December},
url = {http://dx.doi.org/10.1167/1.3.48},
Abstract = {The brightness of any luminant stimulus varies, often quite
markedly, as a function of the context in which it is
presented. An especially intriguing example of this
phenomenon is the illusion described by Chubb and colleagues
(1989) in which the apparent contrast of a patterned target
is reduced when it is embedded in a pattern of the same
spatial frequency but of higher luminance contrast. Illusory
percepts of brightness, like this one, are usually
considered epiphenomena of inhibitory interactions between
neurons tuned to the same attributes of the stimulus, in
this case between neurons in the primary visual cortex
similarly tuned to spatial contrast frequency. Here we
tested a different possibility, namely that the Chubb
illusion is generated according to the experience of the
visual system with background textures seen through an
imperfectly transmitting medium. In agreement with this
suggestion, making the stimulus more consistent with a
contribution to the target of imperfect transmittance
increased the effect for naïve subjects, whereas making the
stimulus less consistent with this possibility decreased the
effect. Because the luminance contrasts and spatial
frequencies of the stimuli were unchanged in these
experiments, these results are difficult to explain in terms
of the receptive field properties of neurons early in the
visual processing stream. Rather, the results suggest that
the Chubb illusion, like other illusions of brightness (and
color), are generated empirically according to what the
sources of the same or similar stimuli have typically turned
out to be in the experience of both the species and the
individual.},
Doi = {10.1167/1.3.48},
Key = {fds268432}
}
@article{fds268433,
Author = {Yang, Z and Purves, D},
Title = {Perception of objects that are both rotating and
translating},
Journal = {Journal of Vision},
Volume = {1},
Number = {3},
Pages = {325-325},
Publisher = {Association for Research in Vision and Ophthalmology
(ARVO)},
Year = {2001},
Month = {December},
url = {http://dx.doi.org/10.1167/1.3.325},
Abstract = {The velocity field generated by a rigid body can be
decomposed into a translation and a rotation in an infinite
number of ways. How, then, can the visual system generate a
definite perception of such stimuli? The conceptual
framework we used to examine this problem is that the
physical motion underlying any image sequence is determined
by: 1) the identity of image features in any two sequential
images; 2) the appearance of new features in the second
image compared to the first; 3) the disappearance of
features in the second image; and 4) any deformation in the
interval between the two images. Accordingly, the stochastic
structure of identity, appearance, disappearance and
deformation in the image plane in relation to the
displacement of the source can be used to generate a 4
dimensional probability distribution of physical movements
underlying the stimulus. Using this approach to study the
perceptions elicited by a line translating and rotating
around a fixed center in different contexts, we found that:
1) the moving line is perceived to rotate but not translate;
2) the perceived centers of rotation fall on a cycloid
defined by all the possible movements underlying the
stimulus; and 3) contexts such as an aperture have no effect
on the nature of this cycloid. The fact that the probability
distribution of the physical displacements underlying the
stimulus accounts for these remarkable percepts supports the
conclusion that motion perception is generated on an
entirely empirical basis.},
Doi = {10.1167/1.3.325},
Key = {fds268433}
}
@article{fds268434,
Author = {Nundy, S and Shimpi, A and Purves, D},
Title = {The relationship between luminance and brightness},
Journal = {Journal of Vision},
Volume = {1},
Number = {3},
Pages = {426-426},
Publisher = {Association for Research in Vision and Ophthalmology
(ARVO)},
Year = {2001},
Month = {December},
url = {http://dx.doi.org/10.1167/1.3.426},
Abstract = {How the luminance of a visual stimulus is translated into a
perceptual value of brightness has been debated since the
middle of the 19th C. Although it seems intuitively clear
that the perception of brightness should scale directly with
the intensity of the light that activates retinal receptors,
this is not the case. Thus, doubling the luminance of a
stimulus under the laboratory conditions in which such
studies are typically done does not double its perceived
brightness. The exponential relationship between luminance
and brightness in these circumstances is referred to as the
Weber-Fechner Law or, alternatively, as Stevens' Power Law.
Although measurements of the relationship between luminance
and brightness have become progressively more sophisticated,
the reason for this relationship and its modification under
more natural viewing conditions has never been explained.
Operating with the assumption that the basis of these
relationships might be based entirely on past experience, we
analyzed the luminance of a visual stimulus as a function of
its generative sources, i.e. the reflectance of and
illumination giving rise to the visual stimulus in both
restricted and more natural scenes. The results of the study
show that the form of the luminance/brightness relationship
changes predictably according to the relative contributions
of reflectance and illumination that would previously have
been experienced in the presence of the same or a similar
stimulus. We conclude, therefore, that the relationship
between luminance and brightness is determined empirically
according the success or failure of visually-guided
behavior.},
Doi = {10.1167/1.3.426},
Key = {fds268434}
}
@article{fds268503,
Author = {Purves, D},
Title = {Viktor Hamburger 1900-2001.},
Journal = {Nature Neuroscience},
Volume = {4},
Number = {8},
Pages = {777-778},
Year = {2001},
Month = {August},
ISSN = {1097-6256},
url = {http://www.ncbi.nlm.nih.gov/pubmed/11477419},
Keywords = {Animals • History, 20th Century • Humans •
Neurosciences • Portraits • United States •
history*},
Doi = {10.1038/90470},
Key = {fds268503}
}
@article{fds268437,
Author = {Lotto, RB and Purves, D},
Title = {An empirical explanation of the Chubb illusion.},
Journal = {Journal of Cognitive Neuroscience},
Volume = {13},
Number = {5},
Pages = {547-555},
Year = {2001},
Month = {July},
ISSN = {0898-929X},
url = {http://www.ncbi.nlm.nih.gov/pubmed/11506656},
Abstract = {The perceived difference in brightness between elements of a
patterned target is diminished when the target is embedded
in a similar surround of higher luminance contrast (the
Chubb illusion). Here we show that this puzzling effect can
be explained by the degree to which imperfect transmittance
is likely to have affected the light that reaches the eye.
These observations indicate that this 'illusion' is yet
another signature of the fundamentally empirical strategy of
visual perception, in this case generated by the typical
influence of transmittance on inherently ambiguous
stimuli.},
Doi = {10.1162/089892901750363154},
Key = {fds268437}
}
@article{fds268436,
Author = {Yang, Z and Shimpi, A and Purves, D},
Title = {A wholly empirical explanation of perceived
motion.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {98},
Number = {9},
Pages = {5252-5257},
Year = {2001},
Month = {April},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/11320255},
Abstract = {Because the retinal activity generated by a moving object
cannot specify which of an infinite number of possible
physical displacements underlies the stimulus, its
real-world cause is necessarily uncertain. How, then, do
observers respond successfully to sequences of images whose
provenance is ambiguous? Here we explore the hypothesis that
the visual system solves this problem by a probabilistic
strategy in which perceived motion is generated entirely
according to the relative frequency of occurrence of the
physical sources of the stimulus. The merits of this concept
were tested by comparing the directions and speeds of moving
lines reported by subjects to the values determined by the
probability distribution of all the possible physical
displacements underlying the stimulus. The velocities
reported by observers in a variety of stimulus contexts can
be accounted for in this way.},
Doi = {10.1073/pnas.091095298},
Key = {fds268436}
}
@article{fds268435,
Author = {Purves, D and Lotto, RB and Williams, SM and Nundy, S and Yang,
Z},
Title = {Why we see things the way we do: evidence for a wholly
empirical strategy of vision.},
Journal = {Philosophical Transactions of the Royal Society of London.
Series B, Biological Sciences},
Volume = {356},
Number = {1407},
Pages = {285-297},
Year = {2001},
Month = {March},
ISSN = {0962-8436},
url = {http://www.ncbi.nlm.nih.gov/pubmed/11316481},
Abstract = {Many otherwise puzzling aspects of the way we see
brightness, colour, orientation and motion can be understood
in wholly empirical terms. The evidence reviewed here leads
to the conclusion that visual percepts are based on patterns
of reflex neural activity shaped entirely by the past
success (or failure) of visually guided behaviour in
response to the same or a similar retinal stimulus. As a
result, the images we see accord with what the sources of
the stimuli have typically turned out to be, rather than
with the physical properties of the relevant objects. If
vision does indeed depend upon this operational strategy to
generate optimally useful perceptions of inevitably
ambiguous stimuli, then the underlying neurobiological
processes will eventually need to be understood within this
conceptual framework.},
Doi = {10.1098/rstb.2000.0772},
Key = {fds268435}
}
@article{fds114090,
Title = {Purves, D., R.B. Lotto, S.M. Williams, S. Nundy and Z.Yang
(2001) Why we see things the way we do: Evidence for a
wholly empirical strategy of vision. Philos. Trans. R. Soc.
Lond. B, 356: 285-297.},
Year = {2001},
Key = {fds114090}
}
@article{fds114091,
Title = {Yang, Z., A. Shimpi and D. Purves (2001) A wholly empirical
explanation of perceived motion. Proc. Natl. Acad. Sci. 9:
5252-5257.},
Year = {2001},
Key = {fds114091}
}
@article{fds268429,
Author = {Lotto, RB and Purves, D},
Title = {An empirical explanation of color contrast.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {97},
Number = {23},
Pages = {12834-12839},
Year = {2000},
Month = {November},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/11058148},
Abstract = {For reasons not well understood, the color of a surface can
appear quite different when placed in different chromatic
surrounds. Here we explore the possibility that these color
contrast effects are generated according to what the same or
similar stimuli have turned out to signify in the past about
the physical relationships between reflectance,
illumination, and the spectral returns they produce. This
hypothesis was evaluated by (i) comparing the physical
relationships of reflectances, illuminants, and spectral
returns with the perceptual phenomenology of color contrast
and (ii) testing whether perceptions of color contrast are
predictably changed by altering the probabilities of the
possible sources of the stimulus. The results we describe
are consistent with a wholly empirical explanation of color
contrast effects.},
Doi = {10.1073/pnas.210369597},
Key = {fds268429}
}
@article{fds268430,
Author = {Nundy, S and Lotto, B and Coppola, D and Shimpi, A and Purves,
D},
Title = {Why are angles misperceived?},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {97},
Number = {10},
Pages = {5592-5597},
Year = {2000},
Month = {May},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/10805814},
Abstract = {Although it has long been apparent that observers tend to
overestimate the magnitude of acute angles and underestimate
obtuse ones, there is no consensus about why such
distortions are seen. Geometrical modeling combined with
psychophysical testing of human subjects indicates that
these misperceptions are the result of an empirical strategy
that resolves the inherent ambiguity of angular stimuli by
generating percepts of the past significance of the stimulus
rather than the geometry of its retinal projection.},
Doi = {10.1073/pnas.97.10.5592},
Key = {fds268430}
}
@article{fds268427,
Author = {Purves, D and Lotto, B and Polger, T},
Title = {Color vision and the four-color-map problem.},
Journal = {Journal of Cognitive Neuroscience},
Volume = {12},
Number = {2},
Pages = {233-237},
Year = {2000},
Month = {March},
ISSN = {0898-929X},
url = {http://www.ncbi.nlm.nih.gov/pubmed/10771407},
Abstract = {Four different colors are needed to make maps that avoid
adjacent countries of the same color. Because the retinal
image is two dimensional, like a map, four dimensions of
chromatic experience would also be needed to optimally
distinguish regions returning spectrally different light to
the eye. We therefore suggest that the organization of human
color vision according to four-color classes (reds, greens,
blues, and yellows) has arisen as a solution to this logical
requirement in topology.},
Doi = {10.1162/089892900562011},
Key = {fds268427}
}
@article{fds268428,
Author = {Purves, D and Williams, SM and Lotto, RB},
Title = {The relevance of visual perception to cortical evolution and
development.},
Journal = {Novartis Foundation Symposium},
Volume = {228},
Pages = {240-254},
Year = {2000},
Month = {January},
ISSN = {1528-2511},
url = {http://www.ncbi.nlm.nih.gov/pubmed/10929326},
Abstract = {The quality of brightness--perhaps the simplest visual
attribute we perceive--appears to be determined
probabilistically. In this empirical conception of the
perception of light, the stimulus-induced activity of visual
cortical neurons does not encode the retinal image or the
properties of the stimulus per se, but associations
(percepts) determined by the relative probabilities of the
possible sources of the stimulus. If this theory is correct,
the rationale for the prolonged postnatal construction of
visual circuitry--and the evolution of this visual
scheme--is to strengthen and/or create by activity-dependent
feedback the empirically determined association on which
vision depends.},
Doi = {10.1002/0470846631.ch16},
Key = {fds268428}
}
@article{fds114057,
Title = {Lotto, R.B. and D. Purves (2000) An empirical explanation of
color contrast. Proc. Natl. Acad. Sci. 97:
12834-12839.},
Year = {2000},
Key = {fds114057}
}
@article{fds114058,
Title = {Purves, D., B. Lotto and T. Polger (2000) Color vision and
the four-color-map problem. J. Cog. Neurosci. 12:
233-237.},
Year = {2000},
Key = {fds114058}
}
@article{fds114087,
Title = {Nundy, S., B. Lotto, D. Coppola, A. Shimpi and D. Purves
(2000) Why are angles misperceived? Proc. Natl. Acad. Sci.
97: 5592-5597.},
Year = {2000},
Key = {fds114087}
}
@article{fds114088,
Title = {Purves, D., G.A. Augustine, D. Fitzpatrick, L.C. Katz, A.-S.
LaMantia and J.O. McNamara (2000) Neuroscience, 2nd edition.
Sinauer Associates: Sunderland, MA.},
Year = {2000},
Key = {fds114088}
}
@article{fds114089,
Title = {Purves, D., S.M. Williams and R.B. Lotto (2000) The
relevance of visual perception to cortical evolution and
development. In: Evolutionary Developmental Biology of the
Cerebral Cortex (Novartis Foundation Symposium Series, G.R.
Bock and G. Cardew, eds.) John Wiley & Sons, Vol. 228, pp.
240-258.},
Year = {2000},
Key = {fds114089}
}
@article{fds268425,
Author = {Purves, D},
Title = {Perception as probability.},
Journal = {Brain Research Bulletin},
Volume = {50},
Number = {5-6},
Pages = {321-322},
Year = {1999},
Month = {November},
ISSN = {0361-9230},
url = {http://www.ncbi.nlm.nih.gov/pubmed/10643417},
Doi = {10.1016/s0361-9230(99)00152-5},
Key = {fds268425}
}
@article{fds268426,
Author = {Lotto, RB and Purves, D},
Title = {The effects of color on brightness.},
Journal = {Nature Neuroscience},
Volume = {2},
Number = {11},
Pages = {1010-1014},
Year = {1999},
Month = {November},
ISSN = {1097-6256},
url = {http://www.ncbi.nlm.nih.gov/pubmed/10526341},
Abstract = {Observation of human subjects shows that the spectral
returns of equiluminant colored surrounds govern the
apparent brightness of achromatic test targets. The
influence of color on brightness provides further evidence
that perceptions of luminance are generated according to the
empirical frequency of the possible sources of visual
stimuli, and suggests a novel way of understanding color
contrast and constancy.},
Doi = {10.1038/14808},
Key = {fds268426}
}
@article{fds268422,
Author = {Purves, D and Shimpi, A and Lotto, RB},
Title = {An empirical explanation of the cornsweet
effect.},
Journal = {The Journal of Neuroscience : the Official Journal of the
Society for Neuroscience},
Volume = {19},
Number = {19},
Pages = {8542-8551},
Year = {1999},
Month = {October},
url = {http://www.ncbi.nlm.nih.gov/pubmed/10493754},
Abstract = {A long-standing puzzle in vision is the assignment of
illusory brightness values to visual territories based on
the characteristics of their edges (the Craik-O'Brien-Cornsweet
effect). Here we show that the perception of the
equiluminant territories flanking the Cornsweet edge varies
according to whether these regions are more likely to be
similarly illuminated surfaces having the same material
properties or unequally illuminated surfaces with different
properties. Thus, if the likelihood is increased that these
territories are surfaces with similar reflectance properties
under the same illuminant, the Craik-O'Brien-Cornsweet
effect is diminished; conversely, if the likelihood is
increased that the adjoining territories are differently
reflective surfaces receiving different amounts of
illumination, the effect is enhanced. These findings
indicate that the Craik-O'Brien-Cornsweet effect is
determined by the relative probabilities of the possible
sources of the luminance profiles in the
stimulus.},
Doi = {10.1523/jneurosci.19-19-08542.1999},
Key = {fds268422}
}
@article{fds268421,
Author = {Halpern, SD and Andrews, TJ and Purves, D},
Title = {Interindividual variation in human visual
performance.},
Journal = {Journal of Cognitive Neuroscience},
Volume = {11},
Number = {5},
Pages = {521-534},
Year = {1999},
Month = {September},
ISSN = {0898-929X},
url = {http://www.ncbi.nlm.nih.gov/pubmed/10511641},
Abstract = {The responses of 20 young adult emmetropes with normal color
vision were measured on a battery of visual performance
tasks. Using previously documented tests of known
reliability, we evaluated orientation discrimination,
contrast sensitivity, wavelength sensitivity, vernier
acuity, direction-of-motion detection, velocity
discrimination, and complex form identification. Performance
varied markedly between individuals, both on a given test
and when the scores from all tests were combined to give an
overall indication of visual performance. Moreover,
individual performances on tests of contrast sensitivity,
orientation discrimination, wavelength discrimination, and
vernier acuity covaried, such that proficiency on one test
predicted proficiency on the others. These results indicate
a wide range of visual abilities among normal subjects and
provide the basis for an overall index of visual proficiency
that can be used to determine whether the surprisingly large
and coordinated size differences of the components of the
human visual system (Andrews, Halpern, & Purves, 1997) are
reflected in corresponding variations in visual
performance.},
Doi = {10.1162/089892999563580},
Key = {fds268421}
}
@article{fds268423,
Author = {Lotto, RB and Williams, SM and Purves, D},
Title = {Erratum: An empirical basis for Mach bands (Proceedings of
the National Academy of Sciences of the United States of
America (April 27, 1999) 96:9 (5239-5244))},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {96},
Number = {13},
Pages = {7610},
Year = {1999},
Month = {June},
url = {http://dx.doi.org/10.1073/pnas.96.13.7610-b},
Doi = {10.1073/pnas.96.13.7610-b},
Key = {fds268423}
}
@article{fds268420,
Author = {Lotto, RB and Williams, SM and Purves, D},
Title = {Mach bands as empirically derived associations.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {96},
Number = {9},
Pages = {5245-5250},
Year = {1999},
Month = {April},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/10220451},
Abstract = {If Mach bands arise as an empirical consequence of
real-world luminance profiles, several predictions follow.
First, the appearance of Mach bands should accord with the
appearance of naturally occurring highlights and lowlights.
Second, altering the slope of an ambiguous luminance
gradient so that it corresponds more closely to gradients
that are typically adorned with luminance maxima and minima
in the position of Mach bands should enhance the illusion.
Third, altering a luminance gradient so that it corresponds
more closely to gradients that normally lack luminance
maxima and minima in the position of Mach bands should
diminish the salience of the illusion. Fourth, the
perception of Mach bands elicited by the same luminance
gradient should be changed by contextual cues that indicate
whether the gradient is more or less likely to signify a
curved or a flat surface. Because each of these predictions
is met, we conclude that Mach bands arise because the
association elicited by the stimulus (the percept)
incorporates these features as a result of past
experience.},
Doi = {10.1073/pnas.96.9.5245},
Key = {fds268420}
}
@article{fds268424,
Author = {Lotto, RB and Williams, SM and Purves, D},
Title = {An empirical basis for Mach bands.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {96},
Number = {9},
Pages = {5239-5244},
Year = {1999},
Month = {April},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/10220450},
Abstract = {Mach bands, the illusory brightness maxima and minima
perceived at the initiation and termination of luminance
gradients, respectively, are generally considered a direct
perceptual manifestation of lateral inhibitory interactions
among retinal or other lower order visual neurons. Here we
examine an alternative explanation, namely that Mach bands
arise as a consequence of real-world luminance gradients. In
this first of two companion papers, we analyze the natural
sources of luminance gradients, demonstrating that
real-world gradients arising from curved surfaces are
ordinarily adorned by photometric highlights and lowlights
in the position of the illusory bands. The prevalence of
such gradients provides an empirical basis for the
generation of this perceptual phenomenon.},
Doi = {10.1073/pnas.96.9.5239},
Key = {fds268424}
}
@article{fds114046,
Title = {Purves, D., A. Shimpi and R.B. Lotto (1999) An empirical
explanation of the Cornsweet effect. J. Neurosci. 19:
8542-8551.},
Year = {1999},
Key = {fds114046}
}
@article{fds114056,
Title = {Lotto, R.B. and D. Purves (1999) The effects of color on
brightness. Nature Neurosci. 2: 1010-1014.},
Year = {1999},
Key = {fds114056}
}
@article{fds114071,
Title = {Lotto, R.B., S.M. Williams and D. Purves (1999) Mach bands
as empirically derived associations. Proc. Natl. Acad. Sci.
96: 5245-5250.},
Year = {1999},
Key = {fds114071}
}
@article{fds114085,
Title = {Halpern, S.D., T.J. Andrews and D. Purves (1999)
Interindividual variation in human visual performance. J.
Cog. Neurosci. 11: 521-534.},
Year = {1999},
Key = {fds114085}
}
@article{fds114086,
Title = {Lotto, R.B., S.M. Williams and D. Purves (1999a) An
empirical basis for Mach bands. Proc. Natl. Acad. Sci. 96:
5239-5244.},
Year = {1999},
Key = {fds114086}
}
@article{fds268418,
Author = {Williams, SM and McCoy, AN and Purves, D},
Title = {The influence of depicted illumination on
brightness.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {95},
Number = {22},
Pages = {13296-13300},
Year = {1998},
Month = {October},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/9789082},
Abstract = {The striking illusions produced by simultaneous brightness
contrast generally are attributed to the center-surround
receptive field organization of lower order neurons in the
primary visual pathway. Here we show that the apparent
brightness of test objects can be either increased or
decreased in a predictable manner depending on how light and
shadow are portrayed in the scene. This evidence suggests
that perceptions of brightness are generated empirically by
experience with luminance relationships, an idea whose
implications we pursue in the accompanying
paper.},
Doi = {10.1073/pnas.95.22.13296},
Key = {fds268418}
}
@article{fds268419,
Author = {Williams, SM and McCoy, AN and Purves, D},
Title = {An empirical explanation of brightness.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {95},
Number = {22},
Pages = {13301-13306},
Year = {1998},
Month = {October},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/9789083},
Abstract = {In this second part of our study on the mechanism of
perceived brightness, we explore the effects of manipulating
three-dimensional geometry. The additional scenes portrayed
here demonstrate that the same luminance profile can elicit
different sensations of brightness as a function of how the
objects in the scene are arranged in space. This further
evidence confirms the implication of the scenes presented in
the accompanying paper, namely that sensations of relative
brightness-including standard demonstrations of simultaneous
brightness contrast-cannot arise by computations of local
contrast. The most plausible explanation of the full range
of perceptual phenomena we have described is an empirical
strategy that links the luminance profile in a visual
stimulus with an association (the percept) that represents
the profile's most probable real-world source.},
Doi = {10.1073/pnas.95.22.13301},
Key = {fds268419}
}
@article{fds268416,
Author = {Coppola, DM and Purves, HR and McCoy, AN and Purves,
D},
Title = {The distribution of oriented contours in the real
world.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {95},
Number = {7},
Pages = {4002-4006},
Year = {1998},
Month = {March},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/9520482},
Abstract = {In both humans and experimental animals, the ability to
perceive contours that are vertically or horizontally
oriented is superior to the perception of oblique angles.
There is, however, no consensus about the developmental
origins or functional basis of this phenomenon. Here, we
report the analysis of a large library of digitized scenes
using image processing with orientation-sensitive filters.
Our results show a prevalence of vertical and horizontal
orientations in indoor, outdoor, and even entirely natural
settings. Because visual experience is known to influence
the development of visual cortical circuitry, we suggest
that this real world anisotropy is related to the enhanced
ability of humans and other animals to process contours in
the cardinal axes, perhaps by stimulating the development of
a greater amount of visual circuitry devoted to processing
vertical and horizontal contours.},
Doi = {10.1073/pnas.95.7.4002},
Key = {fds268416}
}
@article{fds268417,
Author = {Coppola, DM and White, LE and Fitzpatrick, D and Purves,
D},
Title = {Unequal representation of cardinal and oblique contours in
ferret visual cortex.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {95},
Number = {5},
Pages = {2621-2623},
Year = {1998},
Month = {March},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/9482936},
Abstract = {We have measured the amount of cortical space activated by
differently oriented gratings in 25 adult ferrets by optical
imaging of intrinsic signal. On average, 7% more area of the
exposed visual cortex was preferentially activated by
vertical and horizontal contours than by contours at oblique
angles. This anisotropy may reflect the real-world
prevalence of contours in the cardinal axes and could
explain the greater sensitivity of many animals to vertical
and horizontal stimuli.},
Doi = {10.1073/pnas.95.5.2621},
Key = {fds268417}
}
@article{fds114055,
Title = {Williams, S.M., A.N. McCoy and D. Purves (1998) The
influence of depicted illumination on perceived brightness.
Proc Natl Acad Sci 95: 13296-13300.},
Year = {1998},
Key = {fds114055}
}
@article{fds114069,
Title = {Williams, S.M., A.N. McCoy and D. Purves (1998) An empirical
explanation of brightness. Proc. Natl. Acad. Sci. 95:
13301-13306.},
Year = {1998},
Key = {fds114069}
}
@article{fds114083,
Title = {Coppola, D.M, L.E. White, D. Fitzpatrick and D. Purves
(1998) Unequal representation of cardinal and oblique
contours in ferret visual cortex. Proc Natl Acad Sci 95:
2621-2623.},
Year = {1998},
Key = {fds114083}
}
@article{fds114084,
Title = {Coppola, D.M., H.R. Purves, A.N .McCoy and D. Purves
(1998) The distribution of oriented contours in the real
world. Proc Natl Acad Sci 95: 4002-4006.},
Year = {1998},
Key = {fds114084}
}
@article{fds268414,
Author = {Andrews, TJ and Purves, D},
Title = {Similarities in normal and binocularly rivalrous
viewing.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {94},
Number = {18},
Pages = {9905-9908},
Year = {1997},
Month = {September},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/9275224},
Abstract = {We report here a series of observations-most of which the
reader can experience directly-showing that distinct
components of patterned visual stimuli (orthogonal lines of
a different hue) vary in perception as sets. Although less
frequent and often less complete, these perceptual
fluctuations in normal viewing are otherwise similar to the
binocular rivalry experienced when incompatible scenes are
presented dichoptically.},
Doi = {10.1073/pnas.94.18.9905},
Key = {fds268414}
}
@article{fds268411,
Author = {Sporns, O},
Title = {Variation and selection in neural function.},
Journal = {Trends in Neurosciences},
Volume = {20},
Number = {7},
Pages = {291},
Year = {1997},
Month = {July},
url = {http://dx.doi.org/10.1016/S0166-2236(97)88843-1},
Doi = {10.1016/S0166-2236(97)88843-1},
Key = {fds268411}
}
@article{fds268415,
Author = {Purves, D and Andrews, TJ},
Title = {The perception of transparent three-dimensional
objects.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {94},
Number = {12},
Pages = {6517-6522},
Year = {1997},
Month = {June},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/9177250},
Abstract = {When the proximal and distal elements of wire-frame cubes
are conflated, observers perceive illusory structures that
no longer behave veridically. These phenomena suggest that
what we normally see depends on visual associations
generated by experience. The necessity of such learning may
explain why the mammalian visual system is subject to a
prolonged period of plasticity in early life, when novel
circuits are made in enormous numbers.},
Doi = {10.1073/pnas.94.12.6517},
Key = {fds268415}
}
@article{fds268412,
Author = {Andrews, TJ and Halpern, SD and Purves, D},
Title = {Correlated size variations in human visual cortex, lateral
geniculate nucleus, and optic tract.},
Journal = {The Journal of Neuroscience : the Official Journal of the
Society for Neuroscience},
Volume = {17},
Number = {8},
Pages = {2859-2868},
Year = {1997},
Month = {April},
ISSN = {0270-6474},
url = {http://www.ncbi.nlm.nih.gov/pubmed/9092607},
Abstract = {We have examined several components of the human visual
system to determine how the dimensions of the optic tract,
lateral geniculate nucleus (LGN), and primary visual cortex
(V1) vary within the same brain. Measurements were made of
the cross-sectional area of the optic tract, the volumes of
the magnocellular and parvocellular layers of the LGN, and
the surface area and volume of V1 in one or both cerebral
hemispheres of 15 neurologically normal human brains
obtained at autopsy. Consistent with previous observations,
there was a two- to threefold variation in the size of each
of these visual components among the individuals studied.
Importantly, this variation was coordinated within the
visual system of any one individual. That is, a relatively
large V1 was associated with a commensurately large LGN and
optic tract, whereas a relatively small V1 was associated
with a commensurately smaller LGN and optic tract. This
relationship among the components of the human visual system
indicates that the development of its different parts is
interdependent. Such coordinated variation should generate
substantial differences in visual ability among
humans.},
Doi = {10.1523/jneurosci.17-08-02859.1997},
Key = {fds268412}
}
@article{fds114052,
Title = {White, L.E., T. J. Andrews, C. Hulette, A. Richards, M.
Groelle, J. Paydarfar and D. Purves (1997) Structure of
the Human Sensorimotor System II. Lateral symmetry.
Cereb Cortex 7:31-47.},
Year = {1997},
Key = {fds114052}
}
@article{fds114053,
Title = {Purves, D. and T. J. Andrews (1997) The perception of
transparent 3-dimensional objects. Proc Natl Acad Sci 94:
6517-6522.},
Year = {1997},
Key = {fds114053}
}
@article{fds114054,
Title = {Andrews T.J., and D. Purves (1997) Similarities in
normal and binocularly rivalrous viewing. Proc Natl Acad
Sci 94: 9905-9908.},
Year = {1997},
Key = {fds114054}
}
@article{fds114081,
Title = {White L.E., T. J. Andrews, C. Hulette, A. Richards, M.
Groelle, J. Paydarfar and D. Purves (1997) Structure
of the human sensorimotor system I. Morphology and
cytoarchitecture of the central sulcus. Cereb Cortex
7:18-30.},
Year = {1997},
Key = {fds114081}
}
@article{fds114082,
Title = {Andrews T.J., S. D. Halpern and D. Purves (1997)
Correlated size variations in human visual cortex, lateral
geniculate nucleus and optic tract. J Neurosci 17:
2859-2868.},
Year = {1997},
Key = {fds114082}
}
@article{fds268473,
Author = {White, LE and Andrews, TJ and Hulette, C and Richards, A and Groelle, M and Paydarfar, J and Purves, D},
Title = {Structure of the human sensorimotor system. I: Morphology
and cytoarchitecture of the central sulcus.},
Journal = {Cerebral Cortex (New York, N.Y. : 1991)},
Volume = {7},
Number = {1},
Pages = {18-30},
Year = {1997},
ISSN = {1047-3211},
url = {http://www.ncbi.nlm.nih.gov/pubmed/9023429},
Abstract = {We have studied the morphology of the central sulcus and the
cytoarchitecture of the primary sensorimotor cortex in 20
human brains obtained at autopsy. Although the surface
appearance of the central sulcus varies greatly from brain
to brain (and between hemispheres of individual brains), its
deep structure is remarkably consistent. The fundus of the
central sulcus is divided into medial and lateral limbs by a
complex junction midway between the sagittal and Sylvian
fissures. Based on functional imaging studies, this junction
appears to be a structural hallmark of the sensorimotor
representation of the distal upper extremity. We also
identified and measured area 4 (primary motor cortex) and
area 3 (primary somatic sensory cortex) in Nissl-stained
sections cut orthogonal to the course of the central sulcus.
Although the positions of the cytoarchitectonic boundaries
in the paracentral lobule showed considerable
interindividual variation, the locations of the borders of
areas 4 and 3 along the course of the sulcus were similar
among the 40 hemispheres examined. In addition to describing
more thoroughly this portion of the human cerebral cortex,
these observations provide a basis for evaluating lateral
symmetry of the human primary sensorimotor
cortex.},
Doi = {10.1093/cercor/7.1.18},
Key = {fds268473}
}
@article{fds268474,
Author = {White, LE and Andrews, TJ and Hulette, C and Richards, A and Groelle, M and Paydarfar, J and Purves, D},
Title = {Structure of the human sensorimotor system. II: Lateral
symmetry.},
Journal = {Cerebral Cortex (New York, N.Y. : 1991)},
Volume = {7},
Number = {1},
Pages = {31-47},
Year = {1997},
ISSN = {1047-3211},
url = {http://www.ncbi.nlm.nih.gov/pubmed/9023430},
Abstract = {We have evaluated the lateral symmetry of the human central
sulcus, brainstem and spinal cord using quantitative
histological and imaging techniques in specimens from 67
autopsy cases. Our purpose was to determine whether the
preferred use of the right hand in the majority of humans is
associated with grossly discernible asymmetries of the
neural centers devoted to the upper extremities. In the
accompanying report, we described a consistent set of
morphological features in the depths of the central sulcus
that localize the sensorimotor representation of the distal
upper extremity. Measurements of the cortical surface in
this region, and indeed throughout the entire central
sulcus, showed no average lateral asymmetry.
Cytoarchitectonic measurements of area 4 and area 3
confirmed this similarity between the left and right
hemispheres. The medullary pyramids, which contain the
corticospinal tracts, were also symmetrical, as were the
cross-sectional areas of white and gray matter in the
cervical and lumbar enlargements of the spinal cord.
Finally, we found no lateral difference in the size and
number of motor neurons in the ventral horns at these levels
of the cord. Based on these several observations, we
conclude that the preferred use of the right hand in humans
occurs without a gross lateral asymmetry of the primary
sensorimotor system.},
Doi = {10.1093/cercor/7.1.31},
Key = {fds268474}
}
@article{fds268413,
Author = {Purves, D and White, LE and Riddle, DR},
Title = {Is neural development Darwinian?},
Journal = {Trends in Neurosciences},
Volume = {19},
Number = {11},
Pages = {460-464},
Year = {1996},
Month = {November},
ISSN = {0166-2236},
url = {http://www.ncbi.nlm.nih.gov/pubmed/8931267},
Abstract = {Gradually, and without much debate, the idea that the
developing nervous system is in some sense darwinian has
become one of the canons of neurobiology. In fact, there is
little evidence to support this idea.},
Doi = {10.1016/s0166-2236(96)20038-4},
Key = {fds268413}
}
@article{fds268410,
Author = {Coppola, D and Purves, D},
Title = {The extraordinarily rapid disappearance of entoptic
images.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {93},
Number = {15},
Pages = {8001-8004},
Year = {1996},
Month = {July},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/8755592},
Abstract = {It has been known for more than 40 years that images fade
from perception when they are kept at the same position on
the retina by abrogating eye movements. Although aspects of
this phenomenon were described earlier, the use of
close-fitting contact lenses in the 1950s made possible a
series of detailed observations on eye movements and visual
continuity. In the intervening decades, many investigators
have studied the role of image motion on visual perception.
Although several controversies remain, it is clear that
images deteriorate and in some cases disappear following
stabilization; eye movements are, therefore, essential to
sustained exoptic vision. The time course of image
degradation has generally been reported to be a few seconds
to a minute or more, depending upon the conditions. Here we
show that images of entoptic vascular shadows can disappear
in less than 80 msec. The rapid vanishing of these images
implies an active mechanism of image erasure and creation as
the basis of normal visual processing.},
Doi = {10.1073/pnas.93.15.8001},
Key = {fds268410}
}
@article{fds268409,
Author = {Andrews, TJ and White, LE and Binder, D and Purves,
D},
Title = {Temporal events in cyclopean vision.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {93},
Number = {8},
Pages = {3689-3692},
Year = {1996},
Month = {April},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/8622998},
Abstract = {The majority of neurons in the primary visual cortex of
primates can be activated by stimulation of either eye;
moreover, the monocular receptive fields of such neurons are
located in about the same region of visual space. These
well-known facts imply that binocular convergence in visual
cortex can explain our cyclopean view of the world. To test
the adequacy of this assumption, we examined how human
subjects integrate binocular events in time. Light flashes
presented synchronously to both eyes were compared to
flashes presented alternately (asynchronously) to one eye
and then the other. Subjects perceived very-low-frequency (2
Hz) asynchronous trains as equivalent to synchronous trains
flashed at twice the frequency (the prediction based on
binocular convergence). However, at higher frequencies of
presentation (4-32 Hz), subjects perceived asynchronous and
synchronous trains to be increasingly similar. Indeed, at
the flicker-fusion frequency (approximately 50 Hz), the
apparent difference between the two conditions was only 2%.
We suggest that the explanation of these anomalous findings
is that we parse visual input into sequential
episodes.},
Doi = {10.1073/pnas.93.8.3689},
Key = {fds268409}
}
@article{fds268408,
Author = {Purves, D and Paydarfar, JA and Andrews, TJ},
Title = {The wagon wheel illusion in movies and reality.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {93},
Number = {8},
Pages = {3693-3697},
Year = {1996},
Month = {April},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/8622999},
Abstract = {Wheels turning in the movies or in other forms of
stroboscopic presentation often appear to be rotating
backward. Remarkably, a similar illusion is also seen in
continuous light. The occurrence of this perception in the
absence of intermittent illumination suggests that we
normally see motion, as in movies, by processing a series of
visual episodes.},
Doi = {10.1073/pnas.93.8.3693},
Key = {fds268408}
}
@article{fds114050,
Title = {Andrews, T.J., L.E. White, D. Binder and D. Purves (1996)
Temporal events in cyclopean vision. Proc. Natl. Acad.
Sci. 93: 3689-3692.},
Year = {1996},
Key = {fds114050}
}
@article{fds114051,
Title = {Purves, D., L.E. White and D.R. Riddle (1996) Is neural
development Darwinian? Trends Neurosci 19:
460-464.},
Year = {1996},
Key = {fds114051}
}
@article{fds114078,
Title = {Purves, D., J.E. Paydarfar and T.J. Andrews (1996) The
wagon wheel illusion in movies and reality. Proc. Natl.
Acad. Sci. 93: 3693-3697.},
Year = {1996},
Key = {fds114078}
}
@article{fds114079,
Title = {Coppola, D. and D. Purves (1996) The extraordinarily
rapid disappearance of entoptic images. Proc. Natl. Acad.
Sci. 93: 8001-8004.},
Year = {1996},
Key = {fds114079}
}
@article{fds114080,
Title = {Purves D., L. White, D. Zheng, T. Andrews and D. Riddle
(1996) Brain size, behavior and the allocation of neural
space. In: The Lifespan Development of Individuals:
Behavioral, Neurobiological, and Psychosocial
Perspectives, (Magnusson D, ed). Cambridge, UK: Cambridge
University Press, Chapter 8, pp. 162-178.},
Year = {1996},
Key = {fds114080}
}
@article{fds268405,
Author = {Riddle, DR and Purves, D},
Title = {Individual variation and lateral asymmetry of the rat
primary somatosensory cortex.},
Journal = {The Journal of Neuroscience : the Official Journal of the
Society for Neuroscience},
Volume = {15},
Number = {6},
Pages = {4184-4195},
Year = {1995},
Month = {June},
ISSN = {0270-6474},
url = {http://www.ncbi.nlm.nih.gov/pubmed/7790904},
Abstract = {We have evaluated the interindividual variability and
lateral symmetry of a major cortical area by comparing the
primary somatosensory cortex (S1) of adult rats. Our choice
of the rat was dictated by the accuracy with which one can
measure S1 and its component representations in the rodent
brain; the importance of such measurements lies in
understanding the rules that govern the allocation of
cortical space and, ultimately, the consequences of
differential allocation for behavior. With respect to
interindividual differences, the major somatic
representations in S1 are surprisingly variable in size. The
area of the whiskerpad representation, for example, ranged
from 3.72 to 6.84 mm2 in a sample of 53 rats; other
components of S1 showed comparable differences among
animals. With respect to lateral symmetry, the average area
of each major representation was similar for the right and
left hemispheres; thus, we found no consistent bias in the
size of S1 or its elements in the sample as a whole. Within
individual animals, however, the sizes of the major somatic
representations were often quite different in the two
hemispheres. The magnitude of the lateral differences
averaged 7.9 +/- 0.8% (mean +/- SEM) for the whisker pad
representation, 11.6 +/- 1.3% for the upper lip, 15.4 +/-
1.6% for the furry buccal pad, 13.9 +/- 1.4% for the lower
jaw, and 13.3 +/- 1.2% for the forepaw. These results show
that the amount of cortical space allocated to corresponding
functions in individual rats--or in the two hemispheres of a
particular rat--are often different. Such variations are
likely to be reflected in somatosensory performance.},
Doi = {10.1523/jneurosci.15-06-04184.1995},
Key = {fds268405}
}
@article{fds268406,
Author = {Purves, D},
Title = {Race plus IQ does not equal science.},
Journal = {Nature},
Volume = {374},
Number = {6517},
Pages = {10},
Year = {1995},
Month = {March},
url = {http://dx.doi.org/10.1038/374010d0},
Doi = {10.1038/374010d0},
Key = {fds268406}
}
@article{fds268407,
Author = {Zheng, D and Purves, D},
Title = {Effects of increased neural activity on brain
growth.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {92},
Number = {6},
Pages = {1802-1806},
Year = {1995},
Month = {March},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/7892181},
Abstract = {We have measured the effects of regionally increased
metabolic activity--and by inference electrical activity--on
cortical growth in the developing rat brain. Cortical growth
is significantly and specifically greater in regions of
chronically increased activity. This effect of activity on
cortical growth may help explain the permanent storage of
early experience in the developing nervous
system.},
Doi = {10.1073/pnas.92.6.1802},
Key = {fds268407}
}
@article{fds114049,
Title = {Riddle, D.R. and D. Purves (1995) Individual variation
and lateral asymmetry of the rat primary somatosensory
cortex. J. Neurosci. 15: 4184-4195.},
Year = {1995},
Key = {fds114049}
}
@article{fds114075,
Title = {Zheng, D. and D. Purves (1995) The effects of increased
neural activity on brain growth. Proc. Natl. Acad. Sci.
92: 1802-1806.},
Year = {1995},
Key = {fds114075}
}
@article{fds114076,
Title = {Purves, D. (1995) Race plus IQ does not equal science.
Nature 374: 10.},
Year = {1995},
Key = {fds114076}
}
@article{fds114077,
Title = {White, L.E., T.J.Andrews, C. Hulette, A. Richards, M.
Groelle, J. Paydarfar and D. Purves (1995) Structural
symmetry of the human sensorimotor system. Cerebral Cortex
(submitted).},
Year = {1995},
Key = {fds114077}
}
@article{fds268404,
Author = {Purves, D and White, LE},
Title = {Monocular preferences in binocular viewing.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {91},
Number = {18},
Pages = {8339-8342},
Year = {1994},
Month = {August},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/8078884},
Abstract = {Faced with an unobstructed view, both foveas can be readily
aligned with a distant visual target. The minor difference
in the view of the two eyes (which arises from slightly
different lines of sight) presents no special problem and
is, indeed, the basis of stereopsis. However, when
obstructing objects are present in the foreground, the view
provided by one eye becomes wholly or partially incompatible
with the view of the other. We have investigated how we cope
with this everyday situation by having volunteers observe
distant targets through a fenestrated screen. In this
circumstance, subjects naturally position themselves to view
a target of interest with one eye--usually the right eye.
This monocular habit in normal viewing reinforces other
evidence for the unorthodox idea that visual perception
arises from a union in consciousness of monocular images
that are elaborated independently.},
Doi = {10.1073/pnas.91.18.8339},
Key = {fds268404}
}
@article{fds268403,
Author = {Purves, D and White, LE and Andrews, TJ},
Title = {Manual asymmetry and handedness.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {91},
Number = {11},
Pages = {5030-5032},
Year = {1994},
Month = {May},
ISSN = {0027-8424},
url = {http://www.ncbi.nlm.nih.gov/pubmed/8197178},
Abstract = {Volumetric measurements show that right-handed individuals
have larger right hands than left hands. In contrast, the
hands of left-handers are much more nearly symmetrical.
Based on what is known about trophic interactions between
neurons and targets, these findings predict a corresponding
asymmetry of the relevant parts of the sensorimotor system
in right-handers. The lack of an opposite-hand asymmetry
among left-handers further implies that right- and
left-handed phenotypes do not arise according to the same
developmental rules.},
Doi = {10.1073/pnas.91.11.5030},
Key = {fds268403}
}
@article{fds268402,
Author = {White, LE and Lucas, G and Richards, A and Purves,
D},
Title = {Cerebral asymmetry and handedness.},
Journal = {Nature},
Volume = {368},
Number = {6468},
Pages = {197-198},
Year = {1994},
Month = {March},
ISSN = {0028-0836},
url = {http://www.ncbi.nlm.nih.gov/pubmed/8145817},
Doi = {10.1038/368197a0},
Key = {fds268402}
}
@article{fds268401,
Author = {Purves, D and Riddle, DR and White, LE and Gutierrez-Ospina,
G},
Title = {Neural activity and the development of the somatic sensory
system.},
Journal = {Current Opinion in Neurobiology},
Volume = {4},
Number = {1},
Pages = {120-123},
Year = {1994},
Month = {February},
ISSN = {0959-4388},
url = {http://www.ncbi.nlm.nih.gov/pubmed/8173318},
Abstract = {Present thinking about the role of neural activity in the
developing brain is based largely upon observations in the
visual system. Attempts to generalize these findings in the
somatic sensory system, however, have yielded perplexing
results. Unlike the visual system, recent evidence suggests
that activity plays a relatively minor role in establishing
structural patterns in the primary somatic sensory cortex.
Activity levels in the primary somatic sensory cortex are
nonetheless highest in those regions that grow most during
postnatal development, implying that activity promotes
differential cortical growth.},
Doi = {10.1016/0959-4388(94)90041-8},
Key = {fds268401}
}
@article{fds114047,
Title = {White, L., G. Lucas, A. Richards and D. Purves (1994)
Cerebral asymmetry and handedness. Nature 368:
197-198.},
Year = {1994},
Key = {fds114047}
}
@article{fds114048,
Title = {Purves, D. (1994) Neural Activity and the Growth of the
Brain. Cambridge, UK: Cambridge University
Press.},
Year = {1994},
Key = {fds114048}
}
@article{fds114072,
Title = {Purves, D., L. White and T. Andrews (1994) Manual
asymmetry and handedness. Proc Natl Acad Sci 91:
5030-5032.},
Year = {1994},
Key = {fds114072}
}
@article{fds114073,
Title = {Purves, D., D.Riddle, L. White and G. Gutierrez (1994)
Neural activity and the development of the somatic sensory
system. Curr Opin Neurobiol 4: 120-123.},
Year = {1994},
Key = {fds114073}
}
@article{fds114074,
Title = {Purves, D. and L. E. White (1994) Monocular preferences in
binocular viewing. Proc Natl Acad Sci 91:
8339-8342.},
Year = {1994},
Key = {fds114074}
}
@article{fds268400,
Author = {Purves, D and Riddle, DR and White, LE and Gutierrez-Ospina, G and LaMantia, AS},
Title = {Categories of cortical structure.},
Journal = {Progress in Brain Research},
Volume = {102},
Pages = {343-355},
Year = {1994},
ISSN = {0079-6123},
url = {http://www.ncbi.nlm.nih.gov/pubmed/7800824},
Doi = {10.1016/S0079-6123(08)60551-8},
Key = {fds268400}
}
@article{fds268397,
Author = {Riddle, DR and Gutierrez, G and Zheng, D and White, LE and Richards, A and Purves, D},
Title = {Differential metabolic and electrical activity in the
somatic sensory cortex of juvenile and adult
rats.},
Journal = {The Journal of Neuroscience : the Official Journal of the
Society for Neuroscience},
Volume = {13},
Number = {10},
Pages = {4193-4213},
Year = {1993},
Month = {October},
ISSN = {0270-6474},
url = {http://www.ncbi.nlm.nih.gov/pubmed/8410183},
Abstract = {We have examined relative levels of metabolic and electrical
activity across layer IV in the primary somatic sensory
cortex (S1) of the rat in relation to regions of
differential postnatal cortical growth. Each of several
indices used--mitochondrial enzyme histochemistry,
microvessel density, Na+/K+ pump activity, action potential
frequency, and deoxyglucose uptake--indicate regional
variations of metabolic and electrical activity in this part
of the brain in both juvenile (1-week-old) and adult
(10-12-week-old) animals. At both ages, areas of the somatic
sensory map related to special sensors such as whiskers and
digital pads showed evidence of the most intense activity.
Thus, mitochondrial enzyme staining, blood vessel density,
and Na+/K+ ATPase activity were all greatest in the barrels
and barrel-like structures within S1, and least in the
adjacent interbarrel cortex and the cortex surrounding S1.
Multiunit recordings in and around the posteromedial barrel
subfield of anesthetized animals also showed that the
average ratio of evoked to spontaneous activity was greater
in barrels than in the surrounding, metabolically less
active cortex. Furthermore, autoradiograms of labeled
deoxyglucose accumulation in awake behaving animals
indicated systematic differences in neural activity across
S1 barrels and barrel-like structures showed more
deoxyglucose accumulation than interbarrel, nonbarrel, or
peri-S1 cortex. These regional differences in neural
activity correspond to regional differences in neocortical
growth (Riddle et al., 1992). The correlation of greater
electrical activity, increased metabolism, and enhanced
cortical growth during postnatal maturation suggests that
neural activity foments the elaboration of circuitry in the
developing brain.},
Doi = {10.1523/JNEUROSCI.13-10-04193.1993},
Key = {fds268397}
}
@article{fds268396,
Author = {Purves, D and LaMantia, A},
Title = {Development of blobs in the visual cortex of
macaques.},
Journal = {The Journal of Comparative Neurology},
Volume = {334},
Number = {2},
Pages = {169-175},
Year = {1993},
Month = {August},
ISSN = {0021-9967},
url = {http://www.ncbi.nlm.nih.gov/pubmed/8366193},
Abstract = {We have examined the area of the primary visual cortex and
the number and size of blobs within it in 10 neonatal and 11
adult rhesus monkeys. The average area of the primary visual
cortex (V1) increases from 919 mm2 in newborns to 1,069 mm2
in adult animals (16%). The number of blobs decreases per
unit area from an average of 5.2/mm2 at birth to 4.3/mm2 in
maturity (18%). As a consequence, the number of blobs
remains approximately the same during maturation, at about
4,800/hemisphere. These observations correct a preliminary
report on a subset of the animals studied here (Purves and
LaMantia: Proc Natl Acad Sci 87:5765, '90), in which it
appeared that blob number might increase between birth and
maturity. As in other regions of the developing postnatal
brain, we found no net loss of modular circuitry.},
Doi = {10.1002/cne.903340202},
Key = {fds268396}
}
@article{fds268399,
Author = {Purves, D and Riddle, D and LaMantia, A},
Title = {Reply},
Journal = {Trends in Neurosciences},
Volume = {16},
Number = {5},
Pages = {180-181},
Publisher = {Elsevier BV},
Year = {1993},
Month = {January},
ISSN = {0166-2236},
url = {http://dx.doi.org/10.1016/0166-2236(93)90149-G},
Doi = {10.1016/0166-2236(93)90149-G},
Key = {fds268399}
}
@article{fds114070,
Title = {Riddle, D.R., G. Gutierrez, D. Zheng, L. White, A. Richards
and D. Purves (1993) Differential metabolic and electrical
activity in the somatic sensory cortex of juvenile and adult
rats. J. Neurosci. 13: 4193-4213.},
Year = {1993},
Key = {fds114070}
}
@article{fds268398,
Author = {Hevner, RF and Illing, RB and Purves, D and Riddle, D and LaMantia,
A},
Title = {More modules [2]},
Journal = {Trends in Neurosciences},
Volume = {16},
Number = {5},
Pages = {178-180},
Year = {1993},
Key = {fds268398}
}
@article{fds268395,
Author = {Purves, D and Riddle, DR and LaMantia, AS},
Title = {Iterated patterns of brain circuitry (or how the cortex gets
its spots)},
Journal = {Trends in Neurosciences},
Volume = {15},
Number = {10},
Pages = {362-368},
Year = {1992},
Month = {October},
ISSN = {0166-2236},
url = {http://www.ncbi.nlm.nih.gov/pubmed/1279855},
Abstract = {The prominence of repeating patterns of circuitry in the
mammalian brain has led to the general view that iterated
modular units reflect a fundamental principle of cortical
function. Here we argue that these intriguing patterns arise
not because the functional organization of the brain demands
them, but as an incidental consequence of the rules of
synapse formation.},
Doi = {10.1016/0166-2236(92)90180-g},
Key = {fds268395}
}
@article{fds268394,
Author = {Riddle, D and Richards, A and Zsuppan, F and Purves,
D},
Title = {Growth of the rat somatic sensory cortex and its constituent
parts during postnatal development.},
Journal = {The Journal of Neuroscience : the Official Journal of the
Society for Neuroscience},
Volume = {12},
Number = {9},
Pages = {3509-3524},
Year = {1992},
Month = {September},
ISSN = {0270-6474},
url = {http://www.ncbi.nlm.nih.gov/pubmed/1527593},
Abstract = {We have compared the size and arrangement of the primary
somatic sensory cortex (SI) and its constituent parts in
juvenile (1 week old) and mature (10-12 weeks old) rats
using succinic dehydrogenase histochemistry and digital
image analysis. Our goal was to determine whether some
regions of the maturing cortex grow more than others. To
this end, we examined (1) the growth of barrels and the
surrounding (interbarrel) cortex, (2) the growth of the
major somatic representations within SI, and (3) the overall
growth of SI compared to the neocortex as a whole. With
respect to the first of these issues, SI barrels and
barrel-like structures grow more than the intervening
cortex. The growth of these elements varies according to
region: barrels in the head representation more than double
in size, whereas the barrel-like structures in the paw
representations increase by only about half this amount. The
growth of the major somatic representations within SI is
also heterogeneous, the representation of the head enlarging
to a greater extent than the representations of the paws.
Thus, the ratio of the total area of head representation to
the combined paw representation is 15% greater in adults
than in juveniles. Finally, the primary somatic sensory
cortex grows to a somewhat greater extent than the neocortex
as a whole. These observations demonstrate that postnatal
cortical growth is not uniform; it varies among cortical
barrels and the immediately surrounding (interbarrel)
cortex, among the representations of different body parts,
and between SI and the rest of the neocortex. As an
explanation of this differential growth, we suggest that the
neuropil of metabolically (and/or electrically) more active
cortical regions grows to a greater extent during maturation
than that of less active regions.},
Doi = {10.1523/jneurosci.12-09-03509.1992},
Key = {fds268394}
}
@article{fds268393,
Author = {LaMantia, AS and Pomeroy, SL and Purves, D},
Title = {Vital imaging of glomeruli in the mouse olfactory
bulb.},
Journal = {The Journal of Neuroscience : the Official Journal of the
Society for Neuroscience},
Volume = {12},
Number = {3},
Pages = {976-988},
Year = {1992},
Month = {March},
ISSN = {0270-6474},
url = {http://www.ncbi.nlm.nih.gov/pubmed/1545246},
Abstract = {We have monitored the pattern of identified glomeruli in the
olfactory bulbs of newborn, juvenile, and adult mice over
intervals of several hours to several weeks. Our purpose was
to assess the development and stability of these complex
units in the mammalian brain. Glomeruli can be observed by
vital fluorescent staining and laser-scanning confocal
microscopy without causing acute or long-term damage to
brain tissue. Repeated observation of bulbs in the same
animals between birth and 3 weeks of age showed that this
region of the brain develops by progressive addition of
these units to the original population. This increment
occurs by the genesis of smaller new glomeruli between
larger existing ones; no elimination of glomeruli was
observed during this process. Finally, no addition (or loss)
of glomeruli occurred in adult animals over a 2 week
interval; once established, the number, size, and pattern of
glomeruli are evidently stable.},
Doi = {10.1523/jneurosci.12-03-00976.1992},
Key = {fds268393}
}
@article{fds114045,
Title = {LaMantia, A-S., S. Pomeroy and D. Purves (1992) Vital
imaging of glomeruli in the mouse olfactory bulb. J.
Neurosci. 12: 976-988.},
Year = {1992},
Key = {fds114045}
}
@article{fds268392,
Author = {Zheng, D and LaMantia, AS and Purves, D},
Title = {Specialized vascularization of the primate visual
cortex.},
Journal = {The Journal of Neuroscience : the Official Journal of the
Society for Neuroscience},
Volume = {11},
Number = {8},
Pages = {2622-2629},
Year = {1991},
Month = {August},
ISSN = {0270-6474},
url = {http://www.ncbi.nlm.nih.gov/pubmed/1714496},
Abstract = {We have analyzed blood vessel distribution in the primary
and secondary visual cortices of the squirrel monkey in
relation to cortical modules, laminae, and cytoarchitectonic
areas. Measurements of microvessel length in tangential
sections through the primary visual cortex showed that blobs
are more richly vascularized than intervening cortical
regions. Thus, the mean total length of microvessel profiles
per unit was 42% greater within these cortical modules than
within adjacent (interblob) areas. Total microvessel length
per unit area in another class of module, the stripes in the
secondary visual cortex, was 27% greater than in interstripe
regions. Microvessel distribution also varied systematically
from layer to layer in the primary visual cortex, being
greatest in lamina IVc. Finally, the overall microvessel
length per unit area in sections of the primary visual
cortex was 26% greater than that in the secondary visual
cortex. These observations indicate that the modular,
laminar, and regional organization of the primate visual
cortex is reflected in the underlying distribution of
cortical microvessels. These vascular patterns should be
discernable in living animals with vascular contrast agents
and appropriate imaging techniques.},
Doi = {10.1523/jneurosci.11-08-02622.1991},
Key = {fds268392}
}
@article{fds268389,
Author = {Purves, D and LaMantia, AS},
Title = {Numbers of "blobs" in the primary visual cortex of neonatal
and adult monkeys.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {87},
Number = {15},
Pages = {5764-5767},
Year = {1990},
Month = {August},
ISSN = {0027-8424},
url = {http://dx.doi.org/10.1073/pnas.87.15.5764},
Abstract = {We have examined the number of "blobs" (cytochrome
oxidase-positive cortical modules) in the primary visual
cortex (area 17) of infant and adult rhesus monkeys. The
density of these iterated circuits--about five per mm2--was
not significantly different in three newborn and three
mature animals. Measurement of the surface of area 17 in
serial sections, however, showed that the total area
occupied by the primary visual cortex increases by about 50%
during maturation. Based on these measurements, the number
of blobs in this species is about 8000 at birth and about
12,000 in maturity. Evidently, these complex functional
units are added gradually to the developing primate brain
over a period that extends into postnatal
life.},
Doi = {10.1073/pnas.87.15.5764},
Key = {fds268389}
}
@article{fds268391,
Author = {Pomeroy, SL and LaMantia, AS and Purves, D},
Title = {Postnatal construction of neural circuitry in the mouse
olfactory bulb.},
Journal = {The Journal of Neuroscience : the Official Journal of the
Society for Neuroscience},
Volume = {10},
Number = {6},
Pages = {1952-1966},
Year = {1990},
Month = {June},
url = {http://dx.doi.org/10.1523/jneurosci.10-06-01952.1990},
Abstract = {We have undertaken a quantitative analysis of the mouse
olfactory bulb to address several major questions concerning
the development of neural circuitry in the postnatal
mammalian brain. These are: (1) To what degree are new
elements and circuits added during maturation? (2) How long
do such processes go on? and (3) Does postnatal development
involve a net addition of circuits and their constituent
elements, or is there elimination of some portion of an
initial surfeit? Using male mice of known age, weight, and
length, we measured the overall size of the bulb, the
numbers of processing units (glomeruli) within the bulb, the
extent and complexity of postsynaptic dendrites within the
glomeruli, and the number of synapses in different regions
of the bulb. Between birth and the time mice reach sexual
maturity at 6-7 weeks of age, the bulb increases in size by
a factor of 8, the number of glomeruli by a factor of 4-5,
the length of mitral cell dendritic branches by a factor of
11, and the number of glomerular and extraglomerular
synapses by factors of 90 and 170, respectively. Each of
these parameters increases steadily from birth, in concert
with the enlargement of the olfactory mucosa, the overall
growth of the brain, and indeed, of the entire animal. We
found no evidence of an initial surfeit of processing units,
dendritic branches, or synapses. Further elaboration of
neural circuitry by each of these measures is also apparent
from the time of sexual maturity until the animals reach
their full adult size at about 10-12 weeks of age. The
developmental strategy in this part of the mouse brain
evidently involves prolonged construction that persists
until the growth of the body is complete. This ongoing
elaboration of neural circuitry in the postnatal mammalian
brain may be relevant to understanding a number of
unexplained developmental phenomena, including critical
periods, the ability of the juvenile brain to recover from
injuries that would cause severe and permanent deficits in
older animals, and the special ability of the maturing brain
to encode large amounts of new information.},
Doi = {10.1523/jneurosci.10-06-01952.1990},
Key = {fds268391}
}
@article{fds268390,
Author = {Purves, D and LaMantia, AS},
Title = {Construction of modular circuits in the mammalian
brain.},
Journal = {Cold Spring Harbor Symposia on Quantitative
Biology},
Volume = {55},
Pages = {445-452},
Year = {1990},
Month = {January},
ISSN = {0091-7451},
url = {http://www.ncbi.nlm.nih.gov/pubmed/2132831},
Abstract = {Comparison of seemingly different modular units in the
mammalian brain raises the possibility of a common mechanism
for their formation: the growth of neuropil mediated by
trophic interactions. The ongoing postnatal construction of
modular circuits according to trophic interplay may in turn
account for the remarkable plasticity of the juvenile brain.
By the same token, the normal waning of circuit construction
during postnatal development may explain the end of critical
periods, the diminished ability to recover from injury in
older animals, and the decline with increasing age in the
ability of mammals to learn complex skills.},
Doi = {10.1101/sqb.1990.055.01.044},
Key = {fds268390}
}
@article{fds268385,
Author = {LaMantia, AS and Purves, D},
Title = {Development of glomerular pattern visualized in the
olfactory bulbs of living mice.},
Journal = {Nature},
Volume = {341},
Number = {6243},
Pages = {646-649},
Year = {1989},
Month = {October},
url = {http://dx.doi.org/10.1038/341646a0},
Abstract = {Many regions of the mammalian brain are characterized by
iterated ensembles of nerve cells which can be distinguished
anatomically and physiologically. A particularly striking
example is the pattern of glomeruli in the olfactory bulbs;
other instances are columns and 'blobs' in the visual
cortex, barrels and columns in the somatosensory cortex, and
striasomes and cell islands in the neostriatum.
Understanding the generation of these neuronal ensembles has
a bearing on a variety of important neurobiological
problems, including the nature of critical periods, the
age-dependent response of the nervous system to injury and
the manner in which neural information is stored. Analysis
of these issues has usually been restricted to studies of
the brains of different individuals at various ages. Many
questions about the formation of such units, however, can
only be answered by observing the same brain repeatedly in a
living animal. This strategy would enable a direct
assessment of how these units are assembled, whether the
initial ensembles persist and whether units are lost or
gained as an animal matures. We have succeeded in studying
the pattern of glomeruli in the mouse olfactory bulb on two
separate occasions during postnatal development. Comparison
of the patterns observed at intervals of up to three weeks
show that this part of the brain is gradually constructed by
the addition of new glomeruli to a persisting
population.},
Doi = {10.1038/341646a0},
Key = {fds268385}
}
@article{fds268386,
Author = {Harris, LW and Purves, D},
Title = {Rapid remodeling of sensory endings in the corneas of living
mice.},
Journal = {The Journal of Neuroscience : the Official Journal of the
Society for Neuroscience},
Volume = {9},
Number = {6},
Pages = {2210-2214},
Year = {1989},
Month = {June},
url = {http://dx.doi.org/10.1523/jneurosci.09-06-02210.1989},
Abstract = {The terminals of trigeminal neurons were followed over time
in the corneas of living mice by repeated staining with a
nontoxic fluorescent dye. The purpose of these observations
was to evaluate remodeling of sensory nerve endings in an
adult mammal. Video images of topically stained nerve
endings within particular corneal regions were recorded
initially, and then again after intervals ranging from 4 hr
to 30 d. Comparison of the 2 sets of images showed that
sensory endings in the corneal epithelium undergo continual
rearrangement under normal circumstances. Substantial
changes in terminal configuration occurred over periods as
brief as a day.},
Doi = {10.1523/jneurosci.09-06-02210.1989},
Key = {fds268386}
}
@article{fds268387,
Author = {Ivanov, A and Purves, D},
Title = {Ongoing electrical activity of superior cervical ganglion
cells in mammals of different size.},
Journal = {The Journal of Comparative Neurology},
Volume = {284},
Number = {3},
Pages = {398-404},
Year = {1989},
Month = {June},
url = {http://dx.doi.org/10.1002/cne.902840307},
Abstract = {The ongoing synaptic activity of superior cervical ganglion
cells in adult mammals was examined in situ by intracellular
recording in anesthetized mice, hamsters, rats, guinea pigs,
and rabbits. The proportion of neurons exhibiting
subthreshold and suprathreshold synaptic activity during a
standard period of observation was least in a small mammal
like the mouse (30%), intermediate among neurons of mammals
of intermediate size such as the hamster and rat (48% and
45%, respectively), and greatest in the largest animals in
the series, the guinea pig (89%) and rabbit (91%). Ganglion
cells in all species fell silent after transection of the
cervical trunk. The average frequency of synaptic activity
among tonically active cells also increased with animal
size, being least in the mouse (1.0/second) and greatest in
the rabbit (6.4/second). This variation of ongoing synaptic
activity in sympathetic ganglion cells may reflect the
demands of progressively larger peripheral targets on
relatively fixed populations of autonomic
neurons.},
Doi = {10.1002/cne.902840307},
Key = {fds268387}
}
@article{fds268388,
Author = {Purves, D},
Title = {Assessing some dynamic properties of the living nervous
system},
Journal = {Quarterly Journal of Experimental Physiology},
Volume = {74},
Number = {7},
Pages = {1089-1105},
Year = {1989},
url = {http://dx.doi.org/10.1113/expphysiol.1989.sp003335},
Doi = {10.1113/expphysiol.1989.sp003335},
Key = {fds268388}
}
@article{fds268384,
Author = {Purves, D and Snider, WD and Voyvodic, JT},
Title = {Trophic regulation of nerve cell morphology and innervation
in the autonomic nervous system.},
Journal = {Nature},
Volume = {336},
Number = {6195},
Pages = {123-128},
Year = {1988},
Month = {November},
ISSN = {0028-0836},
url = {http://www.ncbi.nlm.nih.gov/pubmed/3054564},
Abstract = {A remarkable feature of nerve cells is the complex and
variable pattern of their axonal and dendritic branches.
Quantitative studies of a simple part of the nervous system
in mammals provide evidence that neuronal geometry and
innervation are regulated by long-term trophic interactions
between neurons and their targets. This trophic linkage may
explain how nerve cells adjust their function to the needs
of bodies that vary markedly in size and
form.},
Doi = {10.1038/336123a0},
Key = {fds268384}
}
@article{fds268383,
Author = {Pomeroy, SL and Purves, D},
Title = {Neuron/glia relationships observed over intervals of several
months in living mice.},
Journal = {The Journal of Cell Biology},
Volume = {107},
Number = {3},
Pages = {1167-1175},
Year = {1988},
Month = {September},
url = {http://dx.doi.org/10.1083/jcb.107.3.1167},
Abstract = {Identified neurons and glial cells in a parasympathetic
ganglion were observed in situ with video-enhanced
microscopy at intervals of up to 130 d in adult mice.
Whereas the number and position of glial cells associated
with particular neurons did not change over several hours,
progressive differences were evident over intervals of weeks
to months. These changes involved differences in the
location of glial nuclei on the neuronal surface,
differences in the apparent number of glial nuclei
associated with each neuron, and often both. When we
examined the arrangement of neurons and glial cells in the
electron microscope, we also found that presynaptic nerve
terminals are more prevalent in the vicinity of glial nuclei
than elsewhere on the neuronal surface. The fact that glial
nuclei are associated with preganglionic endings, together
with the finding that the position and number of glial
nuclei associated with identified neurons gradually changes,
is in accord with the recent observation that synapses on
these neurons are normally subject to ongoing rearrangement
(Purves, D., J. T. Voyvodic, L. Magrassi, and H. Yawo. 1987.
Science (Wash. DC). 238:1122-1126). By the same token, the
present results suggest that glial cells are involved in
synaptic remodeling.},
Doi = {10.1083/jcb.107.3.1167},
Key = {fds268383}
}
@article{fds114044,
Title = {Purves, D., W.D. Snider and J.T. Voyvodic (1988) Trophic
regulation of nerve cell morphology and innervation in the
autonomic nervous system. Nature 336: 123-128.},
Year = {1988},
Key = {fds114044}
}
@article{fds268380,
Author = {Purves, D and Voyvodic, JT and Magrassi, L and Yawo,
H},
Title = {Nerve terminal remodeling visualized in living mice by
repeated examination of the same neuron.},
Journal = {Science (New York, N.Y.)},
Volume = {238},
Number = {4830},
Pages = {1122-1126},
Year = {1987},
Month = {November},
ISSN = {0036-8075},
url = {http://www.ncbi.nlm.nih.gov/pubmed/3685967},
Abstract = {The distribution of presynaptic endings on the surfaces of
autonomic ganglion cells was mapped in living mice after
intravenous administration of a styryl pyridinium dye. The
staining and imaging techniques did not appear to damage the
ganglion cells, or the synapses on them; these procedures
could therefore be repeated after an arbitrary period.
Observations of the same neurons at intervals of up to 3
weeks indicate that the pattern of preganglionic terminals
on many of these nerve cells gradually changes.},
Doi = {10.1126/science.3685967},
Key = {fds268380}
}
@article{fds268496,
Author = {Purves, D and Lichtman, JW},
Title = {Synaptic sites on reinnervated nerve cells visualized at two
different times in living mice.},
Journal = {The Journal of Neuroscience : the Official Journal of the
Society for Neuroscience},
Volume = {7},
Number = {5},
Pages = {1492-1497},
Year = {1987},
Month = {May},
url = {http://dx.doi.org/10.1523/jneurosci.07-05-01492.1987},
Abstract = {Synaptic boutons on the surface of identified autonomic
ganglion cells were visualized by methylene blue staining at
intervals of 1-2 months following denervation to assess
whether regenerating axon terminals reoccupy original
synaptic sites. The distribution of synapses observed on the
same neuronal cell bodies was almost always different in
appearance after reinnervation. These results are at odds
with the conclusions of earlier workers, who have argued
that mammalian neurons bear a fixed number of synaptic
sites, which are reoccupied during reinnervation.},
Doi = {10.1523/jneurosci.07-05-01492.1987},
Key = {fds268496}
}
@article{fds268494,
Author = {Lichtman, JW and Magrassi, L and Purves, D},
Title = {Visualization of neuromuscular junctions over periods of
several months in living mice.},
Journal = {The Journal of Neuroscience : the Official Journal of the
Society for Neuroscience},
Volume = {7},
Number = {4},
Pages = {1215-1222},
Year = {1987},
Month = {April},
url = {http://dx.doi.org/10.1523/jneurosci.07-04-01215.1987},
Abstract = {Identified neuromuscular junctions were followed in the
sternomastoid muscle of living mice for several months by
repeated staining with the fluorescent dye
4-(4-diethylaminostyryl)-N-methylpyridinium iodide
(4-Di-2-ASP; Magrassi et al., 1987). Overall terminal growth
occurred at many endplates; however, the branching pattern
of presynaptic arbors was largely unchanged, even after
several months. The absence of significant remodeling over
time was not a result of dye-staining, since sprouting was
readily induced at residual motor endings by partial
denervation. We conclude that--apart from overall
growth--most neuromuscular junctions in the adult mouse are
stable over intervals that represent a significant fraction
of the animal's lifetime.},
Doi = {10.1523/jneurosci.07-04-01215.1987},
Key = {fds268494}
}
@article{fds268495,
Author = {Magrassi, L and Purves, D and Lichtman, JW},
Title = {Fluorescent probes that stain living nerve
terminals.},
Journal = {The Journal of Neuroscience : the Official Journal of the
Society for Neuroscience},
Volume = {7},
Number = {4},
Pages = {1207-1214},
Year = {1987},
Month = {April},
url = {http://dx.doi.org/10.1523/jneurosci.07-04-01207.1987},
Abstract = {We have evaluated the efficacy of 18 cationic mitochondrial
dyes that, as a class, show some ability to stain living
nerve terminals. Several of these agents provide excellent
staining of neuromuscular junctions in a wide range of
species. More detailed studies of the most effective of
these dyes--4-(4-diethylaminostyryl)-N-methylpyridinium
iodide (4-Di-2-ASP)--indicate that it has no lasting effect
on the structure or function of motor nerve terminals. As
demonstrated in the accompanying paper (Lichtman et al.,
1987; see also Lichtman et al., 1986), 4-Di-2-ASP can
therefore be used to follow the configuration of identified
motor terminals over arbitrarily long intervals.},
Doi = {10.1523/jneurosci.07-04-01207.1987},
Key = {fds268495}
}
@article{fds268381,
Author = {Purves, D and Sanes, JR},
Title = {The 1986 Nobel Prize in physiology or medicine},
Journal = {Trends in Neurosciences},
Volume = {10},
Number = {6},
Pages = {231-235},
Publisher = {Elsevier BV},
Year = {1987},
Month = {January},
ISSN = {0166-2236},
url = {http://dx.doi.org/10.1016/0166-2236(87)90163-9},
Doi = {10.1016/0166-2236(87)90163-9},
Key = {fds268381}
}
@article{fds268382,
Author = {Purves, D and Voyvodic, JT},
Title = {Imaging mammalian nerve cells and their connections over
time in living animals},
Journal = {Trends in Neurosciences},
Volume = {10},
Number = {10},
Pages = {398-404},
Publisher = {Elsevier BV},
Year = {1987},
Month = {January},
ISSN = {0166-2236},
url = {http://dx.doi.org/10.1016/0166-2236(87)90005-1},
Abstract = {A variety of technical advances have provided a means of
following individual nerve cells and their connections over
intervals of weeks or months in living animals. Such
observations allow an assessment of the stability of pre-
and postsynaptic elements in several regions of the nervous
system of adult mammals. © 1987.},
Doi = {10.1016/0166-2236(87)90005-1},
Key = {fds268382}
}
@article{fds268379,
Author = {Purves, D and Hadley, RD and Voyvodic, JT},
Title = {Dynamic changes in the dendritic geometry of individual
neurons visualized over periods of up to three months in the
superior cervical ganglion of living mice.},
Journal = {The Journal of Neuroscience : the Official Journal of the
Society for Neuroscience},
Volume = {6},
Number = {4},
Pages = {1051-1060},
Year = {1986},
Month = {April},
ISSN = {0270-6474},
url = {http://www.ncbi.nlm.nih.gov/pubmed/3701409},
Abstract = {We describe a means of visualizing the same neuron in the
superior cervical ganglion of young adult mice over
intervals of up to 3 months. The dendrites of these neurons
change during this interval; some branches retract, others
elongate, and still others appear to form de novo. Thus,
neuronal dendrites in this part of the nervous system are
subject to continual change beyond what is usually
considered the developmental period. The remodeling of
postsynaptic processes further implies that the synaptic
connections made onto these cells undergo substantial
rearrangement well into adulthood.},
Doi = {10.1523/JNEUROSCI.06-04-01051.1986},
Key = {fds268379}
}
@article{fds268492,
Author = {Purves, D and Rubin, E and Snider, WD and Lichtman,
J},
Title = {Relation of animal size to convergence, divergence, and
neuronal number in peripheral sympathetic
pathways.},
Journal = {The Journal of Neuroscience : the Official Journal of the
Society for Neuroscience},
Volume = {6},
Number = {1},
Pages = {158-163},
Year = {1986},
Month = {January},
url = {http://dx.doi.org/10.1523/jneurosci.06-01-00158.1986},
Abstract = {The enormous range of animal size raises a fundamental
problem: How do larger animals maintain adequate control of
peripheral structures that are many times more massive and
extensive than the homologous structures in smaller animals?
To explore this question, we have determined neuronal
number, the number of axons that innervate each neuron
(convergence) and the number of neurons innervated by each
axon (divergence), in a peripheral sympathetic pathway of
several mammals (mouse, hamster, rat, guinea pig, and
rabbit). The average adult weights of these species vary
over approximately a 65-fold range. However, the number of
superior cervical ganglion cells increases by only a factor
of 4 between the smallest of these animals (mice; about 25
gm) and the largest (rabbits; about 1700 gm); the number of
spinal preganglionic neurons that innervate the ganglion
increases by only a factor of 2. Thus, the number of nerve
cells in the sympathetic system does not increase in
proportion to animal size. On the other hand, our results
indicate that there are systematic differences across these
species in the number of axons that innervate each ganglion
cell and in the number of ganglion cells innervated by each
axon. We suggest that modulation of convergence and
divergence in sympathetic ganglia allows this part of the
nervous system to effectively activate homologous peripheral
targets over a wide range of animal size.},
Doi = {10.1523/jneurosci.06-01-00158.1986},
Key = {fds268492}
}
@article{fds268493,
Author = {Purves, D},
Title = {The trophic theory of neural concentrations},
Journal = {Trends in Neurosciences},
Volume = {9},
Number = {C},
Pages = {486-489},
Publisher = {Elsevier BV},
Year = {1986},
Month = {January},
ISSN = {0166-2236},
url = {http://dx.doi.org/10.1016/0166-2236(86)90155-4},
Doi = {10.1016/0166-2236(86)90155-4},
Key = {fds268493}
}
@article{fds114068,
Title = {Purves, D., R.D. Hadley and J. Voyvodic (1986) Dynamic
changes in the dendritic geometry of individual neurons
visualized over periods of up to three months in the
superior cervical ganglion of living mice. J. Neurosci. 6:
1051-1060.},
Year = {1986},
Key = {fds114068}
}
@article{fds268377,
Author = {Easter, SS and Purves, D and Rakic, P and Spitzer,
NC},
Title = {The changing view of neural specificity.},
Journal = {Science (New York, N.Y.)},
Volume = {230},
Number = {4725},
Pages = {507-511},
Year = {1985},
Month = {November},
ISSN = {0036-8075},
url = {http://dx.doi.org/10.1126/science.4048944},
Abstract = {The generation of specific patterns of neuronal connections
has usually been regarded as a central problem in
neurobiology. The prevailing view for many years has been
that these connections are established by complementary
recognition molecules on the pre- and postsynaptic cells
(the chemoaffinity theory). Experimental results obtained in
the past decade, however, indicate that the view that axon
guidance and synaptogenesis proceed according to restrictive
chemical markers is too narrow. Although a more rigid plan
may prevail in some invertebrates, the formation of specific
connections in vertebrates also involves competition between
axon terminals, trophic feedback between pre- and
postsynaptic cells, and modification of connections by
functional activity.},
Doi = {10.1126/science.4048944},
Key = {fds268377}
}
@article{fds268378,
Author = {Purves, D and Hadley, RD},
Title = {Changes in the dendritic branching of adult mammalian
neurones revealed by repeated imaging in
situ.},
Journal = {Nature},
Volume = {315},
Number = {6018},
Pages = {404-406},
Year = {1985},
Month = {May},
url = {http://dx.doi.org/10.1038/315404a0},
Abstract = {A major obstacle to understanding the mechanism of long-term
change in the vertebrate nervous system has been the
inability to observe the same nerve cell at different times
during the life of an animal. The possibility that changes
in neural connectivity underlie the remarkable flexibility
of the nervous systems of mammals has therefore not been
tested by direct observation. Here, we report studies in
which we have visualized the same neurone in the superior
cervical ganglion of young adult mice at intervals of up to
33 days. This collection of nerve cells is particularly
accessible and therefore well suited to our approach. We
find that the dendritic branches of the neurones examined
change appreciably over intervals of 2 weeks or more; some
branches retract, others elongate and others seem to form de
novo. The apparent remodelling of these postsynaptic
elements implies that the synaptic connections of these
cells normally undergo significant rearrangement beyond what
is usually considered to be the developmental
period.},
Doi = {10.1038/315404a0},
Key = {fds268378}
}
@article{fds268376,
Author = {Purves, D and Lichtman, JW},
Title = {Geometrical differences among homologous neurons in
mammals.},
Journal = {Science (New York, N.Y.)},
Volume = {228},
Number = {4697},
Pages = {298-302},
Year = {1985},
Month = {April},
url = {http://dx.doi.org/10.1126/science.3983631},
Abstract = {The dendritic arbors of sympathetic neurons in different
species of mammals vary systematically: the superior
cervical ganglion cells of smaller mammals have fewer and
less extensive dendrites than the homologous neurons in
larger animals. This difference in dendritic complexity
according to body size is reflected in the convergence of
ganglionic innervation; the ganglion cells of progressively
larger mammals are innervated by progressively more axons.
These relations have implications both for the function of
homologous neural systems in animals of different sizes and
for the regulation of neuronal geometry during
development.},
Doi = {10.1126/science.3983631},
Key = {fds268376}
}
@article{fds114067,
Title = {Purves, D. and J.W. Lichtman (1985) Geometrical differences
among homologous neurons in mammals. Science 228:
298-302.},
Year = {1985},
Key = {fds114067}
}
@article{fds268375,
Author = {Forehand, CJ and Purves, D},
Title = {Regional innervation of rabbit ciliary ganglion cells by the
terminals of preganglionic axons.},
Journal = {The Journal of Neuroscience : the Official Journal of the
Society for Neuroscience},
Volume = {4},
Number = {1},
Pages = {1-12},
Year = {1984},
Month = {January},
url = {http://dx.doi.org/10.1523/jneurosci.04-01-00001.1984},
Abstract = {In the rabbit, ciliary ganglion neurons with dendrites
maintain inputs from several different axons during the
period of synaptic rearrangement that occurs in early
postnatal life. Neurons without dendrites, on the other
hand, lose the majority of their initial inputs and are
innervated in maturity by the terminals of only one or two
axons (Purves, D., and R.I. Hume (1981) J. Neurosci. 1:
441-452; Hume, R.I., and D. Purves (1981) Nature 293:
469-471). We have explored the basis of this phenomenon by
individually marking preganglionic axons and the neurons
they innervate with horseradish peroxidase. In general, the
innervation of geometrically complex (multiply innervated)
neurons by individual preganglionic axons is regional. That
is, the synaptic contacts made by an axon on these neurons
are limited to a portion of the postsynaptic surface that
includes some, but not all, of the dendrites. This regional
innervation of target neurons is consistent with the view
that dendrites allow multiple innervation to persist by
providing relatively separate postsynaptic domains for
individual preganglionic axons. Such regional innervation
may mitigate competitive interactions between the several
axons which initially innervate the same
neuron.},
Doi = {10.1523/jneurosci.04-01-00001.1984},
Key = {fds268375}
}
@article{fds268369,
Author = {Johnson, DA and Purves, D},
Title = {Tonic and reflex synaptic activity recorded in ciliary
ganglion cells of anaesthetized rabbits.},
Journal = {The Journal of Physiology},
Volume = {339},
Pages = {599-613},
Year = {1983},
Month = {June},
url = {http://dx.doi.org/10.1113/jphysiol.1983.sp014737},
Abstract = {We have studied patterns of synaptic activity in rabbit
ciliary ganglion cells by intracellular recording in vivo,
and have examined the morphology of functionally
characterized neurones by intracellular injection of
horseradish peroxidase. Nearly all of the neurones studied
(293 of 300) received tonic synaptic input from
preganglionic neurones. This tonic activity was not
decreased by darkness or by acute optic nerve section. The
rate of tonic synaptic activity recorded in the vast
majority of neurones (94%) changed in response to retinal
illumination. Most ganglion cells showed an increased rate;
some cells, however, showed decreased activity during
illumination. The rate of synaptic activity recorded in
ciliary neurones tended to be progressively higher in
neurones with more complex geometries. Neurones with similar
reflex properties included cells that lacked dendrites and
cells with complex dendritic arborizations; conversely,
neurones with similar geometries often had different reflex
characteristics. The synaptic activity arising from
different preganglionic axons innervating the same ganglion
cell was not temporally linked in any obvious way. The
relevance of these results to the regulation of the number
of axons that innervate target neurones is
discussed.},
Doi = {10.1113/jphysiol.1983.sp014737},
Key = {fds268369}
}
@article{fds268368,
Author = {Hume, RI and Purves, D},
Title = {Apportionment of the terminals from single preganglionic
axons to target neurones in the rabbit ciliary
ganglion.},
Journal = {The Journal of Physiology},
Volume = {338},
Pages = {259-275},
Year = {1983},
Month = {May},
url = {http://dx.doi.org/10.1113/jphysiol.1983.sp014672},
Abstract = {We have studied the apportionment of terminals from single
preganglionic axons to target neurones in the ciliary
ganglion of adult rabbits. Both electrical recording and
intra-axonal injection of horseradish peroxidase (HRP)
showed that each preganglionic axon innervates only a small
fraction of the ganglion cell population (about 10-20 of the
approximately 400 ganglion cells). Examination of ganglia in
whole mounts showed that neurones whose cell bodies were
enveloped by HRP-labelled boutons from a single axon were
often surrounded by other neurones which received no
contacts from the labelled fibre. Electron microscopical
examination of labelled presynaptic terminals on individual
ganglion cells confirmed that the boutons of single axons
were sharply confined to particular target cells. This
suggests that individual target neurones (or portions of
them) are the unit of innervation during the development of
these synaptic connexions. Comparison of the amplitudes of
synaptic responses in singly and multiply innervated
ganglion cells indicated that, on average, an individual
axon made a weaker synaptic connexion with a multiply
innervated neurone than with neurone that received only one
input. Moreover, neurones innervated by several different
axons tended to have fewer synapses on their somata than
neurones innervated by only one or two preganglionic axons.
Individual post-synaptic profiles were often contacted
exclusively by labelled terminals when examined in the
electron microscope. Since many of these neurones are
multiply innervated, this observation suggests some regional
separation of the several inputs contacting the same cell.
For several reasons, however, this inference must be
regarded as tentative. Taken together, these findings
provide a possible explanation of the correlation between
the dendritic geometry of ganglion cells and the number of
different axons that innervate them (Purves & Hume, 1981).
The several axons that initially innervate ganglion cells
without dendrites evidently compete during early life until
only a single input remains. On ganglion cells with
dendrites, however, the number of inputs that persists is
proportional to dendritic complexity. The present results
suggest that the diminished competition between axons
innervating neurones with dendrites may result from some
degree of terminal segregation on dendritic
arborizations.},
Doi = {10.1113/jphysiol.1983.sp014672},
Key = {fds268368}
}
@article{fds268373,
Author = {Lichtman, JW and Purves, D},
Title = {Activity-mediated neural change.},
Journal = {Nature},
Volume = {301},
Number = {5901},
Pages = {563},
Year = {1983},
Month = {February},
url = {http://dx.doi.org/10.1038/301563a0},
Doi = {10.1038/301563a0},
Key = {fds268373}
}
@article{fds268370,
Author = {Purves, D},
Title = {Modulation of neuronal competition by postsynaptic geometry
in autonomic ganglia},
Journal = {Trends in Neurosciences},
Volume = {6},
Number = {C},
Pages = {10-16},
Publisher = {Elsevier BV},
Year = {1983},
Month = {January},
ISSN = {0166-2236},
url = {http://dx.doi.org/10.1016/0166-2236(83)90007-3},
Abstract = {The number of axons that innervate autonomic ganglion cells
is the result of competition in early life between terminals
contacting the same target cell. In maturity, a correlation
between the number of inputs a cell receives and dendritic
complexity implies that geometry modulates neuronal
competition. These observations suggest a novel view of the
role that dendrites play in neuronal development. ©
1983.},
Doi = {10.1016/0166-2236(83)90007-3},
Key = {fds268370}
}
@article{fds268371,
Author = {Purves, D and Wigston, DJ},
Title = {Neural units in the superior cervical ganglion of the
guinea-pig.},
Journal = {The Journal of Physiology},
Volume = {334},
Pages = {169-178},
Year = {1983},
Month = {January},
url = {http://dx.doi.org/10.1113/jphysiol.1983.sp014487},
Abstract = {The size and arrangement of the set of neurones innervated
by individual preganglionic axons (the neural unit) has been
investigated in the superior cervical ganglion of the
guinea-pig. 1. Based on the ratio of preganglionic neurones
to ganglion cells, and the average number of axons
contacting each ganglion cell, we estimated that individual
preganglionic axons innervate on the order of 50-200
superior cervical ganglion cells. 2. Of 562 pairs of
ganglion cells examined with intracellular recording,
forty-seven (8.4%) were innervated by one or more common
axons. 3. Pairs of ganglion cells innervated by the same
axon were not necessarily near each other. Although nearby
cells were more likely to share innervation than neurones
far apart, cells sharing innervation were often found
several hundred micrometers apart, and were occasionally
separated by the largest dimension of the ganglion (about
1-2 mm). 4. The incidence of cell pairs that shared
innervation from more than one axon was greater than
expected from the frequency of pairs sharing at least one
axon. 5. Extracellular recordings from small fascicles of
the cervical sympathetic trunk showed that preganglionic
axons from different segmental levels intermingle
extensively en route to the superior cervical ganglion. 6.
Taken together, these findings support the view that sets of
ganglion cells are innervated in common not because of any
special topographic relationship within the ganglion, but
because they share one or more properties that make them
especially attractive to particular preganglionic
axons.},
Doi = {10.1113/jphysiol.1983.sp014487},
Key = {fds268371}
}
@article{fds268372,
Author = {Purves, D and Lichtman, JW},
Title = {Specific connections between nerve cells.},
Journal = {Annual Review of Physiology},
Volume = {45},
Pages = {553-565},
Year = {1983},
Month = {January},
url = {http://dx.doi.org/10.1146/annurev.ph.45.030183.003005},
Doi = {10.1146/annurev.ph.45.030183.003005},
Key = {fds268372}
}
@article{fds268367,
Author = {Hume, RI and Purves, D},
Title = {Geometry of neonatal neurones and the regulation of synapse
elimination.},
Journal = {Nature},
Volume = {293},
Number = {5832},
Pages = {469-471},
Year = {1981},
Month = {October},
url = {http://dx.doi.org/10.1038/293469a0},
Abstract = {In the ciliary ganglion of adult rabbits, ganglion cells
lacking dendrites are generally innervated by a single axon,
whereas cells with one or more dendrites are innervated by a
number of different axons that increases in proportion to
the complexity of their dendritic arbor. We have now
explored the basis of this correlation by comparing the
dendritic arborization of cells receiving different numbers
of axons during and after the period of synapse elimination
that occurs early in postnatal life. Our results suggest
that the geometry of neonatal neurones influences the
competitive interaction between the several axons that
initially innervate the same cell. This finding in turn
implies that an important function of dendrites is to
regulate the number of different axons that ultimately
innervate each neurone.},
Doi = {10.1038/293469a0},
Key = {fds268367}
}
@article{fds268363,
Author = {Johnson, DA and Purves, D},
Title = {Post-natal reduction of neural unit size in the rabbit
ciliary ganglion.},
Journal = {The Journal of Physiology},
Volume = {318},
Pages = {143-159},
Year = {1981},
Month = {September},
url = {http://dx.doi.org/10.1113/jphysiol.1981.sp013855},
Abstract = {We have studied the innervation of adult and neonatal
ciliary ganglia in the rabbit to determine the average
number of ganglion cells innervated by each preganglionic
neurone at different stages of development. 1. The adult
ciliary ganglion comprises about 380 ganglion cells which
are innervated by about forty preganglionic neurones. 2.
Ciliary ganglion cells in adult rabbits are on average
innervated by 2.2 different axons; in contrast, neonatal
ganglion cells are on average innervated by 4.6 different
axons. The transition to the adult pattern of innervation
occurs gradually during the first few post-natal weeks. 3.
The numbers of ganglion cells and preganglionic neurones do
not change appreciably after birth. Accordingly, the loss of
some innervation to individual neurones during post-natal
development indicates that each preganglionic axon
innervates progressively fewer ciliary ganglion cells. 4.
The number of synaptic boutons found in ganglia at birth,
however, is less than the number of synaptic boutons found
in adult ganglia. 5. We conclude that synaptic connexions in
this ganglion age gradually rearranged in early post-natal
life such that each preganglionic neurone focuses an
increasing number of synaptic contacts on a progressively
smaller subset of the ganglion cell population.},
Doi = {10.1113/jphysiol.1981.sp013855},
Key = {fds268363}
}
@article{fds268366,
Author = {Purves, D and Hume, RI},
Title = {The relation of postsynaptic geometry to the number of
presynaptic axons that innervate autonomic ganglion
cells.},
Journal = {The Journal of Neuroscience : the Official Journal of the
Society for Neuroscience},
Volume = {1},
Number = {5},
Pages = {441-452},
Year = {1981},
Month = {May},
url = {http://dx.doi.org/10.1523/jneurosci.01-05-00441.1981},
Abstract = {We have studied the shape of rabbit ciliary ganglion cells
in relation to the number of axons that innervate each
neuron. Adult ganglion cells receive synapses from one to
seven different preganglionic axons. Some neurons lack
dendrites altogether, whereas others have complex
arborizations of up to eight primary dendrites. The neurons
that receive all of their synaptic contacts from a single
preganglionic axon usually have no dendrites; on the other
hand, multiply innervated ganglion cells receive synapses
from a number of different axons that increases in
proportion to the number of primary dendrites that they
possess. A possible explanation of these results is that
individual ciliary ganglion cells comprise a number of
separate spatial domains, each of which is largely
constrained to receive innervation from a single
preganglionic axon.},
Doi = {10.1523/jneurosci.01-05-00441.1981},
Key = {fds268366}
}
@article{fds268365,
Author = {Purves, D and Thompson, W and Yip, JW},
Title = {Re-innervation of ganglia transplanted to the neck from
different levels of the guinea-pig sympathetic
chain.},
Journal = {The Journal of Physiology},
Volume = {313},
Pages = {49-63},
Year = {1981},
Month = {January},
url = {http://dx.doi.org/10.1113/jphysiol.1981.sp013650},
Abstract = {Thoracic and lumbar sympathetic ganglia from donor
guinea-pigs were transplanted to the bed of an excised
superior cervical ganglion in host animals. Homotopic
transplants of superior cervical ganglia served as controls.
In this way the same set of preganglionic axons (the
cervical sympathetic trunk) was confronted with ganglia from
different levels of the sympathetic chain. Re-innervation of
the transplants was studied after 3-5 months. 1. Neurones in
ganglia transplanted from different levels of the
sympathetic chain were re-innervated to about the same
over-all degree by the preganglionic axons of the host's
cervical sympathetic trunk. Thus, the mean amplitude of
post-synaptic potentials, the estimated number of
innervating axons, and the number of spinal segments
providing innervation to each neurone were similar in
transplanted thoracic, lumbar and superior cervical ganglion
cells. 2. Neurones in transplanted mid-thoracic ganglia,
however, were re-innervated more frequently, and more
strongly, by axons arising from more caudal thoracic
segments than neurones in transplanted superior cervical
ganglia. Stimulation of axons arising from the fourth
thoracic spinal segment (T4), for example, elicited
post-synaptic potentials that on average were twice as large
in transplanted fifth thoracic ganglion cells as in
transplanted superior cervical ganglion cells; conversely,
axons arising from T1 re-innervated neurones in the superior
cervical ganglion about 2-3 times more effectively than
fifth thoracic ganglion cells. This difference in the
re-innervation of the fifth thoracic and the superior
cervical ganglion is in the same direction as (although less
pronounced than) the normal difference in the segmental
innervation of these ganglia. 3. Transplanted lumbar ganglia
were also re-innervated more effectively by relatively
caudal segments compared to re-innervated cervical ganglia,
but this difference was no greater than that observed for
transplanted thoracic ganglia. 4. We conclude that
preganglionic axons can distinguish (or be distinguished by)
ganglia derived from different levels of the sympathetic
chain. Our findings are consistent with the view that
ganglion cells have some permanent property that biases the
innervation they receive.},
Doi = {10.1113/jphysiol.1981.sp013650},
Key = {fds268365}
}
@article{fds340940,
Author = {Purves, D and Johnson, DA and Hume, RI},
Title = {Regulation of synaptic connections in the rabbit ciliary
ganglion.},
Journal = {Ciba Foundation Symposium},
Volume = {83},
Pages = {232-251},
Year = {1981},
url = {http://dx.doi.org/10.1002/9780470720653.ch12},
Abstract = {One of the intriguing questions about the establishment of
synaptic connections is how appropriate numbers of different
axons come to innervate each target neuron. A reorganization
of connections in early postnatal life appears to be an
important aspect of this process, since many of the axons
terminals that initially innervate target cells are
subsequently lost. The rabbit ciliary ganglion is a
remarkably simple neural ensemble in which to examine this
rearrangement of developing synaptic connections. Using this
system we have found that a reduction in the number of axons
innervating each cell occurs without any change in the
number of ciliary ganglion cells or preganglionic neurons;
therefore the rearrangement is not based on cell death. The
number of different axons that ultimately innervate each
cell is, however, influenced in some way by the geometry of
individual target neurons. Thus, mature ganglion cells that
lack dendrites are generally innervated by a single axon,
while neurons with increasingly complex dendritic arbors
receive innervation from a commensurate number of different
axons. At birth, on the other hand, neurons with or without
dendritic processes receive about the same number of
preganglionic inputs. These results suggest that the
geometry of the target cell influences the competitive
interaction between different axons innervating the same
neuron. Indeed, an important function of dendrites may be to
regulate the number of axons that innervate each nerve
cell.},
Doi = {10.1002/9780470720653.ch12},
Key = {fds340940}
}
@article{fds268361,
Author = {Purves, D and Lichtman, JW},
Title = {Elimination of synapses in the developing nervous
system.},
Journal = {Science (New York, N.Y.)},
Volume = {210},
Number = {4466},
Pages = {153-157},
Year = {1980},
Month = {October},
ISSN = {0036-8075},
url = {http://dx.doi.org/10.1126/science.7414326},
Abstract = {Reduction of the number of axons that contact target cells
may be a general feature of neural development. This process
may underlie the progressively restricted malleability of
the maturing nervous system.},
Doi = {10.1126/science.7414326},
Key = {fds268361}
}
@article{fds268362,
Author = {Purves, D},
Title = {Neuronal competition.},
Journal = {Nature},
Volume = {287},
Number = {5783},
Pages = {585-586},
Year = {1980},
Month = {October},
ISSN = {0028-0836},
url = {http://dx.doi.org/10.1038/287585a0},
Doi = {10.1038/287585a0},
Key = {fds268362}
}
@article{fds268359,
Author = {Rubin, E and Purves, D},
Title = {Segmental organization of sympathetic preganglionic neurons
in the mammalian spinal cord.},
Journal = {The Journal of Comparative Neurology},
Volume = {192},
Number = {1},
Pages = {163-174},
Year = {1980},
Month = {July},
url = {http://dx.doi.org/10.1002/cne.901920111},
Abstract = {We have used retrograde transport of horseradish peroxidase
to determine the distribution of the preganglionic cell
bodies whose axons join particular rami of the thoracic
spinal cord in a series of guinea pigs, and in a small
number of hamsters and cats. In contrast to other recent
studies, our results show that the neurons sending axons to
a ramus are confined to a single segment at the
corresponding spinal level. This segmental organization
supports the idea that the rostro-caudal position of
preganglionic cell bodies is one determinant of selective
synapse formation between preganglionic axons and
sympathetic ganglion cells.},
Doi = {10.1002/cne.901920111},
Key = {fds268359}
}
@article{fds268360,
Author = {Lichtman, JW and Purves, D},
Title = {The elimination of redundant preganglionic innervation to
hamster sympathetic ganglion cells in early post-natal
life.},
Journal = {The Journal of Physiology},
Volume = {301},
Pages = {213-228},
Year = {1980},
Month = {April},
url = {http://dx.doi.org/10.1113/jphysiol.1980.sp013200},
Abstract = {The superior cervical ganglion of adult and neonated
hamsters has been studied with intracellular recording. 1.
Neurones in adult hamster ganglia are innervated by an
average of 6-7 preganglionic axons. During the first week of
post-natal life, however, these cells are innervated by at
least eleven to twelve axons. Ganglion cells in animals 2-3
weeks old are innervated to an intermediate degree,
indicating that these neurones lose a substantial portion of
their initial synaptic contacts during the first weeks after
birth. 2. The over-all innervation of the superior cervical
ganglion in adult hamsters arises from thoracic segments
T1-T5; no additional segments contribute significantly to
the innervation of neonatal ganglia. 3. The average number
of segments innervating each adult ganglion cell is 2 . 8
compared to 3 . 7 segments innervating neonatal neurones.
Throughout post-natal development the innervation of
individual neurones arises from a contiguous subset of the
spinal segments that innervate the ganglion as a whole. 4.
We conclude that the elimination of redundant innervatin in
early life is not limited to those nerve and muscle cells
contacted by a sigle axon in maturity, but also occurs in
sympathetic ganglia where adult neurones remain multiply
innervated. Moreover, the loss of some synaptic contacts
during development refines the selective innervation of
individual neurones.},
Doi = {10.1113/jphysiol.1980.sp013200},
Key = {fds268360}
}
@article{fds268358,
Author = {Lichtman, JW and Purves, D and Yip, JW},
Title = {Innervation of sympathetic neurones in the guinea-pig
thoracic chain.},
Journal = {The Journal of Physiology},
Volume = {298},
Pages = {285-299},
Year = {1980},
Month = {January},
url = {http://dx.doi.org/10.1113/jphysiol.1980.sp013081},
Abstract = {We have investigated the organization of the guinea-pig
thoracic chain by studying the innervation of the stellate
and fifth thoracic sympathetic ganglia with intracellular
recording. 1. These ganglia receive preganglionic
innervation from different but overlapping sets of spinal
cord segments: the stellate ganglion is innervated by
preganglionic axons from spinal segments more rostral than
those supplying the fifth thoracic ganglion, but somewhat
more caudal than those innervating the superior cervical
ganglion. 2. Individual thoracic ganglion cells are
innervated by only some of the spinal segments that supply
each ganglion as a whole. In general, the subset of spinal
segments innervating a ganglion cell is contiguous; one of
these segments provides the strongest innervation, with
progressively weaker innervation arising from spinal levels
adjacent to the dominant one. This selective pattern of
innervation is similar to that in the superior cervical
ganglion (Njå & Purves, 1977 a). 3. Preganglionic axons
frequently innervate neurones in more than one ganglion. 4.
Although neurones innervated by the same spinal cord
segments are found in both the stellate and the fifth
thoracic ganglion, as well as in the superior cervical, the
number of ganglion cells receiving innervation from
particular spinal segments is different in each ganglion.
Moreover, neurones dominated by the same segment but located
in different ganglia receive somewhat different average
innervation from adjacent segments as a function of the
ganglion in which they reside. 5. These results indicate
that neurones in the thoracic chain ganglia, as those in the
superior cervical ganglion, are selectively innervated by
particular spinal cord segments. We suggest that the
different average innervation of sympathetic ganglia
reflects at least two related factors: the selective
qualities of their constituent neurones, and the
availability of different preganglionic axons to each
ganglion.},
Doi = {10.1113/jphysiol.1980.sp013081},
Key = {fds268358}
}
@article{fds268488,
Author = {Lichtman, JW and Purves, D and Yip, JW},
Title = {On the purpose of selective innervation of guinea-pig
superior cervical ganglion cells.},
Journal = {The Journal of Physiology},
Volume = {292},
Pages = {69-84},
Year = {1979},
Month = {July},
url = {http://dx.doi.org/10.1113/jphysiol.1979.sp012839},
Abstract = {Preganglionic axons arising from different levels of the
mammalian spinal cord make preferential connexions with
different classes of superior cervical ganglion cells
(Langley, 1892, 1900; Njå & Purves, 1977a). For example,
preganglionic axons from the first thoracic segment (T1)
make relatively strong connexions with ganglion cells
activating end-organs of the eye; conversely, axons arising
from T4 selectively innervate ganglion cells projecting to
the ear. In the present work we have asked whether this
selectivity reflects the function of the pre- and
post-synaptic cells, and aspect of their respective
positions, or some other criterion. 1. End-organs with
different functions at the same locus (the eye) respond to
stimulation of the same ventral roots; end-organs of a
single modality (hairs or blood vessels) at different
positions, however, tend to be activated by different spinal
segments. Thus the segmental innervation of ganglion cells
is correlated with the position rather than the function of
post-ganglionic targets. 2. The role of target position in
ganglion cell innervation was examined directly by recording
from neurones sending axons to different destinations.
Superior cervical ganglion cells running dorso-medially in a
spinal nerve receive, on average, innervation from more
caudal segments than cells projecting ventro-laterally. 3.
These selective connexions do not depend on intraganglionic
cell position: neurones located at different points along
the major axes of the superior cervical ganglion receive, on
average, the same segmental innervation. In accord with this
observation, retrogradely labelled neurones innervating a
particular target such as the eye or ear are widely and
randomly distributed within a large portion of the ganglion.
Thus the importance of post-ganglionic target position in
ganglion cell innervation is not simply a reflexion of
ganglionic topography. 4. We conclude that one purpose of
the selective connexions in the superior cervical ganglion
is to bring together preganglionic axons arising from
different levels of the spinal cord and ganglion cells whose
axons innervate particular regions of the superior cervical
territory.},
Doi = {10.1113/jphysiol.1979.sp012839},
Key = {fds268488}
}
@article{fds268491,
Author = {Purves, D and Thompson, W},
Title = {The effects of post-ganglionic axotomy on selective synaptic
connexions in the superior cervical ganglion of the
guinea-pig.},
Journal = {Journal of Physiology},
Volume = {297},
Pages = {95-110},
Year = {1979},
url = {http://dx.doi.org/10.1113/jphysiol.1979.sp013029},
Abstract = {Stimulation of preganglionic axons arising from different
levels of the thoracic spinal cord causes different effects
on end-organs supplied by the superior cervical ganglion
(Langley, 1892; Nja & Purves, 1977a; Lichtman, Purves
& Yip, 1979). For example, stimulation of the first
thoracic ventral root (T1) causes pupillary dilatation and
widening of the palpebral fissure; stimulation of T4, on the
other hand, has little effect on the eye, even though axons
arising from this level innervate about as many superior
cervical ganglion cells as those from T1. Thus ganglion cell
innervation is selective. (1) Three months after crushing
the major post-ganglionic branches of the superior cervical
ganglion this differential effectiveness is lost: T1 and T4
stimulation have approximately equal effects on the
end-organs of the eye. (2) In normal animals, the cellular
counterpart of selective end-organ effects is the
innervation of each ganglion cell by a contiguous subset of
the spinal segments that innervate the ganglion as a whole.
One of these segments is usually dominant, the strength of
innervation from adjacent segments falling off as a function
of distance from the dominant one (Nja & Purves, 1977a).
Intracellular recordings from ganglion cells 3 months after
post-ganglionic axotomy showed that this selective pattern
is re-established. (3) Since the innervation of ganglion
cells appears normal, the abnormal end-organ responses after
post-ganglionic axotomy suggest that ganglion cell axons are
not limited to their original targets during peripheral
re-innervation. This suggestion is supported by the finding
that ganglion cells sending axons to different peripheral
destinations via the second and third cervical spinal nerves
were no longer distinguishable on the basis of their
segmented inputs 3 months after post-ganglionic axotomy. (4)
Similar results were obtained when the preganglionic
cervical trunk was cut at the same time as the
post-ganglionic axons were crushed; the pattern of end-organ
responses was abnormal, whereas individual ganglion cells
were re-innervated according to the rules of contiguity and
segmental dominance. (5) These results indicate that
ganglion cells do not undergo a compensatory change in the
segmental innervation they receive when their axons
regenerate to targets different from, or in addition to
those they originally innervated, even when an entirely new
set of ganglionic connexions is formed. This suggests that
ganglion cells, or some aspect of their immediate
environment, possess a permanent label that determines the
segmental innervation they receive.},
Doi = {10.1113/jphysiol.1979.sp013029},
Key = {fds268491}
}
@article{fds268489,
Author = {Purves, D and Lichtman, JW},
Title = {Formation and maintenance of synaptic connections in
autonomic ganglia.},
Journal = {Physiological Reviews},
Volume = {58},
Number = {4},
Pages = {821-862},
Year = {1978},
Month = {October},
url = {http://dx.doi.org/10.1152/physrev.1978.58.4.821},
Abstract = {The purpose is to review results that shed some light on the
way in which specific patterns of synaptic connections are
established and maintained in autonomic ganglia and, by
analogy, perhaps in other parts of the nervous
system.},
Doi = {10.1152/physrev.1978.58.4.821},
Key = {fds268489}
}
@article{fds268490,
Author = {Njå, A and Purves, D},
Title = {Specificity of initial synaptic contacts made on guinea-pig
superior cervical ganglion cells during regeneration of the
cervical sympathetic trunk.},
Journal = {The Journal of Physiology},
Volume = {281},
Pages = {45-62},
Year = {1978},
Month = {August},
url = {http://dx.doi.org/10.1113/jphysiol.1978.sp012408},
Abstract = {1. Largely appropriate synaptic connexions are formed with
neurones in the superior cervical ganglion at long intervals
after interruption of the preganglionic nerve. In the
present study we have assessed the accuracy of connexions
during the early stages of re-innervation by observing
end-organ responses to ventral root stimulation in vivo, and
by recording intracellularly from ganglion cells during
ventral root stimulation in isolated preparations. 2.
Appropriate, but weak, end-organ responses were elicited by
stimulation of the first and fourth thoracic ventral roots
(T1 and T4) 15--30 days after freezing the cervical
sympathetic trunk. 3. Intracellular recordings from ganglion
cells during stimulation of the ventral roots C8--T7 in
vitro showed that synaptic contacts are first re-established
8--11 days after freezing the preganglionic nerve. The
proportion of re-innervated cells, and the strength of
innervation of individual neurones, increased rapidly for up
to about 3 months after nerve injury, but showed little
change thereafter. Innervation remained weaker than normal
even after 6 months. 4. Patterns of segmental innervation
recorded intracellularly during the early stages of
regeneration were similar to, but more restricted than
normal. Even 13--19 days after interruption of the
preganglionic nerve, neurones re-innervated by more than one
spinal cord segment tended to be innervated by a contiguous
subset of the spinal segments which contribute innervation
to the ganglion. The incidence of neurones receiving
innervation from a discontinuous segmental subset was about
the same at early and late stages or re-innervation. 5.
Throughout the course of nerve regeneration, re-innervated
neurones tended to receive dominant synaptic input from
axons arising at a particular spinal level, as do normal
cells, with adjacent segments contributing a synaptic
influence that diminished as a function of distance from the
dominant segment. 6. The results of these experiments argue
against the initial formation of imprecise connexions with
subsequent retention of appropriate contacts and a loss of
inappropriate ones. Rather our findings suggest that the
re-innervation of ganglion cells proceeds by a gradual
accumulation of synaptic connexions which are, from the
outset, appropriate.},
Doi = {10.1113/jphysiol.1978.sp012408},
Key = {fds268490}
}
@article{fds268487,
Author = {Njå, A and Purves, D},
Title = {The effects of nerve growth factor and its antiserum on
synapses in the superior cervical ganglion of the
guinea-pig.},
Journal = {The Journal of Physiology},
Volume = {277},
Number = {1},
Pages = {53-75},
Publisher = {WILEY},
Year = {1978},
Month = {April},
url = {http://dx.doi.org/10.1113/jphysiol.1978.sp012260},
Abstract = {1. The effects of nerve growth factor (NGF) and its
antiserum on synapses in the superior cervical ganglion of
the guinea-pig have been examined by intracellular recording
and electron microscopy. 2. Exogenous NGF, supplied locally
from a silicone rubber pellet implanted near ganglia for 4-7
days, had little effect on either the function or the number
of ganglionic synapses. 3. However, the depression of
synaptic transmission and loss of synaptic contacts on
ganglion cells which follow post-ganglionic axotomy were
diminished by about 50% in the presence of exogenous NGF. 4.
Other post-axotomy changes such as the development of
subthreshold regenerative responses in neuronal processes,
the appearance of ultrastructurally abnormal neuronal
profiles suggesting rapid membrane turnover, and the
cytoplasmic and nuclear changes characteristic of
"chromatolysis", were also largely prevented by exogenous
NGF. 5. Systemic treatment of neonatal and young adult
guinea-pigs with antiserum to NGF for 4-5 days caused
depression of intracellularly recorded synaptic responses
within 5-8 days of the end of antiserum administration.
Synapse counts in electron microscopical sections from these
ganglia showed only about half as many contacts as in
control ganglia from animals receiving normal rabbit serum.
6. These findings suggest that the loss of synapses from
sympathetic neurones which follows axotomy results from a
reduction in the amount of NGF supplied to ganglion cells. A
corollary is that, among other biological roles, NGF is
required by peripheral sympathetic neurones to maintain the
synapses they receive.},
Doi = {10.1113/jphysiol.1978.sp012260},
Key = {fds268487}
}
@article{fds268486,
Author = {Nja, A and Purves, D},
Title = {Re-innervation of guinea-pig superior cervical ganglion
cells by preganglionic fibres arising from different levels
of the spinal cord.},
Journal = {The Journal of Physiology},
Volume = {272},
Number = {3},
Pages = {633-651},
Year = {1977},
Month = {November},
url = {http://dx.doi.org/10.1113/jphysiol.1977.sp012064},
Abstract = {1. The ability of preganglionic axons to re-establish their
normal pattern of synaptic connexions with superior cervical
ganglion cells has been studied after section of the
cervical sympathetic trunk.2. In vivo stimulation of the
last cervical (C8) and the first seven thoracic ventral
roots (T1-T7) 3-4 months after section of the trunk produced
end-organ responses similar to those observed in normal
animals.3. The pattern of innervation of individual
neurones, determined by intracellular recording of synaptic
potentials 4-9 months after cutting the sympathetic trunk,
was also similar to that observed in normal neurones. Both
normal and re-innervated ganglion cells were contacted by
pre-ganglionic axons arising from C8 to T7, and each neurone
was usually innervated by a contiguous subset of these
segments.4. Re-innervated neurones, as normal cells, were
typically dominated by the innervation from a particular
spinal cord segment, with the adjacent segments contributing
a synaptic influence that decreased as a function of
distance from the dominant segment. This was true whether
the amplitude of the post-synaptic potential, or the
estimated number of contributing axons, was used as the
criterion of segmental dominance.5. Re-innervated neurones,
however, showed some abnormalities. The average number of
ventral roots contributing innervation to each neurone was
reduced from 4.1 to 3.0, and discontinuities in the sequence
of innervating segments were more frequent than in normal
neurones. Moreover, fewer preganglionic axons contacted each
neurone after regeneration.6. A further difference between
normal and re-innervated neurones during the period covered
by these experiments was that axons from the more caudal
spinal cord segments were less successful in re-establishing
contacts with ganglion cells than those from the rostral
segments. The more caudal the position of the preganglionic
neurones, the more pronounced was this relative
deficiency.7. Although anomalies of ganglion cell
innervation were apparent, the basis for the restoration of
normal functional effects appears to be the re-establishment
of a pattern of innervation of individual neurones similar
to that observed in normal ganglia.},
Doi = {10.1113/jphysiol.1977.sp012064},
Key = {fds268486}
}
@article{fds268485,
Author = {Njå, A and Purves, D},
Title = {Specific innervation of guinea-pig superior cervical
ganglion cells by preganglionic fibres arising from
different levels of the spinal cord.},
Journal = {The Journal of Physiology},
Volume = {264},
Number = {2},
Pages = {565-583},
Year = {1977},
Month = {January},
url = {http://dx.doi.org/10.1113/jphysiol.1977.sp011683},
Abstract = {1. The synaptic contribution of preganglionic nerve fibres
arising from the last cervical (C8) and the first seven
thoracic spinal cord segments (T1-T7) to neurones of the
guinea-pig superior cervical ganglion has been studied by
means of intracellular recording during ventral root
stimulation in vitro. 2. The majority of neurones received
innervation from the middle segments (T2 and T3) of the
length of spinal cord from which preganglionic fibres
derive; an intermediate number of ganglion cells were
innervated by fibres from the segments adjacent to these
(T1, T4, and T5), and relatively few neurones by fibres from
the most rostral and caudal segments supplying innervation
to the ganglion (C8, T6 and T7). 3. Each neurone received
preganglionic terminals from multiple thoracic segments
(range 1-7, mean = 4-0). The estimated minimum number of
preganglionic fibres contacting each neurone was 10, on
average. 4. As a rule, the spinal segments innervating a
neurone were contiguous. Thus we rarely encountered neurones
innervated by segments located both rostrally and caudally
to a segment which failed to provide innervation. 5.
Neurones tended to be innervated predominantly by axons
arising from a single spinal segment, with adjacent segments
contributing a synaptic influence that diminished as a
function of their distance from the dominant segment. All
segments provided dominant innervation to at least some
neurones. 6. Stimulating the ventral roots of C8-T7 in vivo
showed that the axons arising from each segment produced a
characteristic pattern of peripheral effects. Thus different
populations of neurones in the superior cervical ganglion of
the guinea-pig are innervated by preganglionic axons from
different levels of the spinal cord, as originally suggested
by Langley (1892) for the cat, dog, and rabbit. 7. On the
basis of our in vitro studies we conclude that underlying
the specificity of innervation of neurones of the superior
cervical ganglion that can be inferred from in vivo
experiments is a tendency for individual neurones to be
innervated in a systematically graded fashion by a
contiguous subset of the eight spinal segments which provide
innervation to the ganglion.},
Doi = {10.1113/jphysiol.1977.sp011683},
Key = {fds268485}
}
@article{fds268482,
Author = {Purves, D},
Title = {Competitive and non-competitive re-innervation of mammalian
sympathetic neurones by native and foreign
fibres.},
Journal = {The Journal of Physiology},
Volume = {261},
Number = {2},
Pages = {453-475},
Year = {1976},
Month = {October},
url = {http://dx.doi.org/10.1113/jphysiol.1976.sp011568},
Abstract = {The ability of native (sympathetic preganglionic) and
foreign (vagal) nerve fibres to re-innervate neurones of the
guinea-pig superior cervical ganglion, either alone or in
competition with each other, has been studied by means of
intracellular recording and electron microscopy. 1. Native
fibres make synaptic contacts with nearly all ganglion cells
within one month of cervical trunk section; within 6 months
the degree of innervation, judged by measurement of
excitatory post-synaptic potential (e.p.s.p.) amplitude and
electron microscopical synapse counts, approaches normal.
However, even after 15 months innervation was weaker than in
normal control ganglia. 2. Vagal fibres are less successful
during re-innervation. Although a similar number of foreign
fibres grown into denervated ganglia and make contact with
nearly all ganglion cells within a month, after 6-12 months
e.p.s.p. amplitudes in response to foreign nerve stimulation
remain relatively small, and counts of synapses are only
about 60% as great as in ganglia re-innervated with the
native nerve. 3. When both native and foreign fibres are
allowed to re-innervate ganglion cells simultaneously, about
half the neurones in the ganglion receive synapses from both
sources after 1 month. The proportion of dually invervated
cells remains roughly constant for at least 14 months.
Neither set of preganglionic fibres dominates or displaces
the other, although neurones generally are re-innervated
more effectively by native than foreign fibres, as is true
during non-competitive re-innervation. 4. Thus during
re-innervation of mammalian sympathetic neurones native
fibres are preferred to foreign ones only in the sense that
roughly the same number of native fibres form many more
synapses on ganglion cells than do vagal axons. A foreign
synapse, once formed, is as stable as a native one, and
shows no tendency to be replaced by native terminals. These
findings are discussed in relation to other evidence which
has suggested specificity and selectivity during
re-innervation of mammalian autonomic neurones.},
Doi = {10.1113/jphysiol.1976.sp011568},
Key = {fds268482}
}
@article{fds268481,
Author = {Purves, D},
Title = {Functional and structural changes in mammalian sympathetic
neurones following colchicine application to post-ganglionic
nerves.},
Journal = {The Journal of Physiology},
Volume = {259},
Number = {1},
Pages = {159-175},
Year = {1976},
Month = {July},
url = {http://dx.doi.org/10.1113/jphysiol.1976.sp011459},
Abstract = {1. The effects of post-ganglionic colchicine application on
neurones of the guinea-pig superior cervical ganglion were
studied with intracellular recording and electron
microscopy. 2. Local colchicine application for 30 min to
one of the major post-ganglionic nerves caused several
electrophysiological changes after 4-7 days in many neurones
whose axons run in this nerve. These changes include: (a) a
reduction in the amplitude of synaptic potentials elicited
by supramaximal preganglionic stimulation; (b) a decrease in
the number of preganglionic fibres innervating individual
neurones; (c) the development of regenerative responses in
dendrites; and (d) the failure of antidromic action
potentials to fully invade the neuronal soma. These
functional changes occurred in the absence of impaired
impulse conduction or axon degeneration, and were not
observed in nearby neurones whose axons ran in an untreated
post-ganglionic nerve. The effects of colchicine are similar
to the changes produced by axotomy. 3. Counts of synapses in
thin sections from the region of the ganglion where the
affected neurones were located showed a reduction, compared
to the number of synapses in other regions of the colchicine
treated ganglia, or normal control ganglia. This finding
indicates that synaptic depression after colchicine
treatment, like that after axotomy, is due primarily to a
loss of synaptic contacts from the dendrites of affected
nerve cells. Unusual profiles containing numerous vesicular
and tubular organelles frequently seen after interruption of
the axons were also observed in thin sections after
colchicine treatment. 4. The similarity of the
electrophysiological and ultrastructural effects of
colchicine treatment and axon interruption offers further
support for the view that synaptic contacts on sympathetic
neurones are normally regulated by an interaction of the
neuronal soma with its axonal extension to the
periphery.},
Doi = {10.1113/jphysiol.1976.sp011459},
Key = {fds268481}
}
@article{fds268484,
Author = {Purves, D and Njå, A},
Title = {Effect of nerve growth factor on synaptic depression after
axotomy.},
Journal = {Nature},
Volume = {260},
Number = {5551},
Pages = {535-536},
Year = {1976},
Month = {April},
url = {http://dx.doi.org/10.1038/260535a0},
Abstract = {The authors report that exogenous NGF can, to a large
extent, prevent the synaptic depression seen in adult
sympathetic ganglion cells after interruption of their
axons. Ten adult guinea pigs were used.},
Doi = {10.1038/260535a0},
Key = {fds268484}
}
@article{fds268477,
Author = {Roper, S and Purves, D and McMahan, UJ},
Title = {Synaptic organization and acetylcholine sensitivity of
multiply innervated autonomic ganglion cells.},
Journal = {Cold Spring Harbor Symposia on Quantitative
Biology},
Volume = {40},
Pages = {283-295},
Year = {1976},
Month = {January},
url = {http://dx.doi.org/10.1101/sqb.1976.040.01.029},
Abstract = {The principal cells of the mudpuppy cardiac ganglion receive
synapses from three sources: vagal axons, interneurons and
axon collaterals from other principal cells. The simplicity
of the structural organization and the visual clarity in the
living preparation provide favorable conditions for
examining the function of these synapses and how different
classes of synapses on the same cell influence its function.
We have studied the sensitivity of the principal cells to
iontophoretically applied acetylcholine--the transmitter at
synapses made by the vagal axons and by postganglionic axon
collaterals from other principal cells. In normal ganglia,
the ACh sensitivity on the cell surface is highest at the
region of synapses. Partial denervation, produced by
severing the vagus nerves, results in an increased ACh
sensitivity in nonsynaptic areas but does not appear to
affect synaptic transmission at the remaining
synapses.},
Doi = {10.1101/sqb.1976.040.01.029},
Key = {fds268477}
}
@article{fds268479,
Author = {McMahan, UJ and Purves, D},
Title = {Visual identification of two kinds of nerve cells and their
synaptic contacts in a living autonomic ganglion of the
mudpuppy (Necturus maculosus).},
Journal = {The Journal of Physiology},
Volume = {254},
Number = {2},
Pages = {405-425},
Year = {1976},
Month = {January},
url = {http://dx.doi.org/10.1113/jphysiol.1976.sp011238},
Abstract = {1. Many of the nerve cells comprising the cardiac
parasympathetic ganglion of the mudpuppy are spread out in a
thin, transparent sheet of tissue, enabling one to see
cellular details in living preparations with differential
interference contrast optics. The aim of this study was
twofold: to establish the morphology of the nerve cells and
their synaptic connections by light and electron microscopy,
and to determine which aspects of the ganglion's structure
could be reliably identified in the living tissue. 2. There
are two types of neurones in the ganglion: (a) principal
cells that send post-ganglionic axons to cardiac muscle
fibres, and (b) interneurones whose processes are confined
to the ganglion. 3. Interneurones are distinguished from
principal cells by the presence of numerous granular
vesicles seen with the electron microscope, and by intense
formaldehyde-induced fluorescence. The interneurones are
thus similar to catecholamine-containing interneurones in
autonomic ganglia of other vertebrates. 4. Principal cells
are innervated by processes that terminate mainly on the
cell body, forming up to forty-five synaptic boutons and
covering, on the average, 5% of the perikaryal surface. The
synaptic terminals are derived from three sources: (a) axons
from the vagus nerves, (b) interneurones and (c) other
principal cells. Vagal terminals contacting principal cells
contain agranular vesicles typical of preganglionic
cholinergic endings. At regions of contact between processes
of interneurones and principal cells, the interneurones have
granular vesicles focused at membrane specializations; in
addition there are small areas of close plasma membrane
apposition, probably gap junctions. Some of the contacts
between principal cells are characterized by gap junctions;
others are structurally similar to vagal endings but persist
after vagal degeneration. 6. Interneurones are innervated by
axons that make contact mainly with their processes. The
axon terminals on processes of interneurones contain
agranular vesicles similar to vagal terminals on principal
cells. 7. In live preparations principal cells are
distinguished from interneurones by their size and the
appearance of their organelles. Synaptic contacts on
principal cells could often be identified and, in some
cases, large contacts from interneurones or those from other
nearby principal cells could be traced back to their cell
bodies of origin. The validity of these identifications was
confirmed by subsequent electron microscopic examination of
the same cells.},
Doi = {10.1113/jphysiol.1976.sp011238},
Key = {fds268479}
}
@article{fds268478,
Author = {Purves, D},
Title = {Functional and structural changes in mammalian sympathetic
neurones following interruption of their
axons.},
Journal = {The Journal of Physiology},
Volume = {252},
Number = {2},
Pages = {429-463},
Year = {1975},
Month = {November},
url = {http://dx.doi.org/10.1113/jphysiol.1975.sp011151},
Abstract = {The effects of interrupting the axons of principal neurones
in the superior cervical ganglion of adult guinea-pigs were
studied by means of intracellular recording, and light and
electron microscopy. 1. Within 72 hr of axon interruption,
the amplitude of exitatory postsynaptic potentials
potentials (e.p.s.p.s) recorded in principal neurons in
response to maximal preganglionic stimulation declined.
E.p.s.p.s were maximally reduced (by more than 70% on
average) 4-7 days following interruption, and failed to
bring many cells to threshold. E.p.s.p.s. recorded in nearby
neurones whose axons remained intact were unaffected. 2. In
ganglia in which axon interruption was achieved by means of
nerve crush (thus allowing prompt regeneration), mean
e.p.s.p. amplitudes began to increase again after about 1-2
weeks. One month after the initial injury many neurones had
e.p.s.p.s of normal amplitude, and by 2 months affected
neurones were indistinguishable from control cells.
Functional peripheral connexions were re-established during
the period of synaptic recovery. 3. The mean number of
synapses identified electron microscopically in ganglia in
which all the major efferent branches had been crushed
decreased by 65-70% in parallel with synaptic depression
measured by intracellular recording. However synapse counts
did not return to normal levels even after 3 months. 4.
During the period of maximum synaptic depression, numerous
abnormal profiles which contained accumulations of vesicular
and tubular organelles, vesicles, and mitochondria were
observed in electron microscopic sections. Injection of
horseradish peroxidase into affected neurones demonstrated
dendritic swelling which probably correspond to these
profiles. 5. Little or no difference was found in the
electrical properties of normal neurones and neurones whose
axons had been interrupted 4-7 days previously. However, the
mean amplitude of spontaneously occurring synaptic
potentials was reduced, and the amplitude distribution was
shifted. This abnormality of the synapses which remain on
affected neurones also contributes to synaptic depression.
6. Counts of neurones in normal and experimental ganglia
showed that approximately half the principal cells died 1-5
weeks after crushing the major efferent brances. This
finding presumably explains the failure of synapse counts to
return to control levels after recovery. 7. If axons were
prevented from growing back to their target organ by chronic
ligation, surviving neurones whose axons were enclosed by
the ligature did not generally recover normal synaptic
function. Following ligation, most affected cells died
within a month. 8. Thus the integrity of a principal cell's
axon is necessary for the maintenance of preganglionic
synaptic contacts, and ultimately for neuronal survival. The
basis of neuronal recovery from the effects of axon
interruption appears to be some aspect of regeneration to
the peripheral target.},
Doi = {10.1113/jphysiol.1975.sp011151},
Key = {fds268478}
}
@article{fds268480,
Author = {Purves, D},
Title = {Persistent innervation of mammalian sympathetic neurones by
native and foreign fibres.},
Journal = {Nature},
Volume = {256},
Number = {5518},
Pages = {589-590},
Year = {1975},
Month = {August},
url = {http://dx.doi.org/10.1038/256589a0},
Doi = {10.1038/256589a0},
Key = {fds268480}
}
@article{fds268483,
Author = {Roper, S and Purves, D and McMahan, UJ},
Title = {Synaptic organization and acetylcholine sensitivity of
multiply innervated autonomic ganglion cells},
Journal = {Symposia on Quantitative Biology},
Volume = {Vol. 40},
Pages = {283-295},
Year = {1975},
Month = {January},
Abstract = {The principal cells of the mudpuppy cardiac ganglion receive
synapses from three sources: vagal axons, interneurons and
axon collaterals from other principal cells. The simplicity
of the structural organization and the visual clarity in the
living preparation provide favorable conditions for
examining the function of these synapses and how different
classes of synapses on the same cell influence its function.
We have studied the sensitivity of the principal cells to
iontophoretically applied acetylcholine, the transmitter at
synapses made by the vagal axons and by postganglionic axon
collaterals from other principal cells. In normal ganglia,
the ACh sensitivity on the cell surface is highest at the
region of synapses. Partial denervation, produced by
severing the vagus nerves, results in an increased ACh
sensitivity in monosynaptic areas but does not appear to
affect synaptic transmission at the remaining
synapses.},
Key = {fds268483}
}
@article{fds268357,
Author = {Purves, D and Sakmann, B},
Title = {Membrane properties underlying spontaneous activity of
denervated muscle fibres.},
Journal = {The Journal of Physiology},
Volume = {239},
Number = {1},
Pages = {125-153},
Year = {1974},
Month = {May},
ISSN = {0022-3751},
url = {http://dx.doi.org/10.1113/jphysiol.1974.sp010559},
Abstract = {We have examined the events underlying the initiation of
spontaneous action potentials (fibrillation) in fibres of
previously denervated rat diaphragm maintained in organ
culture for up to 10 days.1. Based on discharge pattern, two
classes of spontaneously active fibres were found:
rhythmically discharging fibres, and fibres in which action
potentials occur at irregular intervals.2. Sites of action
potentials initiation were located by exploration along the
fibre length with two independent extracellular recording
electrodes. The majority of sites of origin in both regular
and irregular fibres were at the former end-plate zone;
however, there was no region along the length that could
not, at least in some fibres, be a site of origin.3.
Intracellular recording at or near sites of origin of action
potential discharge showed two types of initiating events.
Irregularly discharging fibres were brought to threshold by
discrete depolarizations of up to 15 mV in amplitude, while
regularly occurring action potentials were associated with
oscillations of the membrane potential.4. Discrete
depolarizations (called fibrillatory origin potentials or
f.o.p.s) at sites of origin in irregularly discharging
fibres have the following properties: (a) random occurrence
and nearly constant amplitude outside a refractory period
during which both amplitude and probability of a second
f.o.p. are reduced; (b) associated inward current flow which
is localized to about 100 mum or less along the fibre
length, and (c) dependence of amplitude and frequency on
membrane potential.5. Oscillation of membrane potential
found at sites of origin of action potential discharge in
regular fibres also occurred locally along the fibre length
and was sensitive to changes in membrane potential.6. Both
f.o.p.s and oscillations of membrane potential were
reversibly abolished by low Na(+)-Ringer fluid or
tetrodotoxin.7. Neither type of initiating event was
appreciably affected by concentrations of D-tubocurarine
which blocked extrajunctional sensitivity to
acetylcholine.8. We conclude that spontaneous action
potentials under these conditions arise from a localized
Na(+)-conductance change in the membrane of the active
fibre; this conductance change is distinct from the
increased Na(+)-conductance which follows the interaction of
acetylcholine with its receptor. Spontaneous activity in
single, denervated muscle fibres is cyclical and
self-inhibiting (Purves & Sakmann, 1974); thus the
Na(+)-conductance change underlying the initiation of
spontaneous action potentials is affected by muscle fibre
activity.},
Doi = {10.1113/jphysiol.1974.sp010559},
Key = {fds268357}
}
@article{fds268356,
Author = {Purves, D and Sakmann, B},
Title = {The effect of contractile activity on fibrillation and
extrajunctional acetylcholine-sensitivity in rat muscle
maintained in organ culture.},
Journal = {The Journal of Physiology},
Volume = {237},
Number = {1},
Pages = {157-182},
Year = {1974},
Month = {February},
ISSN = {0022-3751},
url = {http://dx.doi.org/10.1113/jphysiol.1974.sp010475},
Abstract = {1. The effect of contractile activity on the initiation of
spontaneous action potentials (fibrillation) and on
extrajunctional acetylcholine-sensitivity has been studied
in single fibres in strips of previously denervated rat
diaphragm maintained in organ culture for up to 10 days.2.
Following removal of the diaphragm from the animal,
fibrillation slowed and usually stopped altogether for about
24-36 hr. Thereafter, spontaneously active fibres were found
in all cultured muscle strips.3. At any one time, about
(1/4) to (1/3) of fibres impaled with micro-electrodes were
active (defined as more than one action potential/10 sec),
with a mean discharge frequency of 4.5/sec (range
0.1-24/sec).4. The duration of continuous activity in single
fibres was, on average, 21-22 hr; a period of activity was
followed by a longer inactive interval. Thus activity in
single fibres is cyclical.5. Direct stimulation of
fibrillating strips for 24 hr at 10/sec suppressed
spontaneous activity for 1-3 days.6. Conversely, blockade of
spontaneous activity with tetrodotoxin for 72 hr led to a
two- to threefold increase in the number of fibrillating
fibres when the drug was washed out; in some strips nearly
all fibres became spontaneously active.7. The mean rate of
activity of diaphragm fibres during normal breathing,
determined by recording single units from the phrenic nerve
in lightly anaesthetized animals, is about 18/sec.8. Direct
stimulation of cultured diaphragm strips in a pattern
similar to breathing for 7-8 days at an average rate of
10-12/sec (or 5/sec in some experiments), resulted in a
marked reduction (about 95% in experiments at 10/sec) in
extrajunctional sensitivity to ionophoretically applied
ACh.9. Direct stimulation for 24 hr at 10/sec (comparable to
a period of spontaneous activity) caused only a small
reduction in extrajunctional ACh-sensitivity.10. We conclude
that spontaneous activity in single fibres under these
conditions occurs cyclically because activity, over a period
of hours, inhibits the ability of the fibrillating fibre to
initiate further action potentials. Repeated self-inhibition
of spontaneous activity probably explains why denervated
muscle fibres remain highly sensitive to extrajunctionally
applied ACh.},
Doi = {10.1113/jphysiol.1974.sp010475},
Key = {fds268356}
}
@article{fds268355,
Author = {Purves, D and McMahan, UJ},
Title = {The distribution of synapses on a physiologically identified
motor neuron in the central nervous system of the leech. An
electron microscope study after the injection of the
fluorescent dye procion yellow.},
Journal = {The Journal of Cell Biology},
Volume = {55},
Number = {1},
Pages = {205-220},
Year = {1972},
Month = {October},
url = {http://dx.doi.org/10.1083/jcb.55.1.205},
Abstract = {The fine structure of a physiologically identified motor
neuron in the segmental ganglion of the leech central
nervous system and the morphology of synapses on it were
studied after injection of the fluorescent dye Procion
yellow as a marker. The injected cell and its processes
within the neuropil were located in thick or thin sections
with fluorescence optics after initial fixation with
glutaraldehyde and brief treatment with osmium tetroxide.
The same or adjacent thin sections could then be examined in
the electron microscope. Comparison with uninjected cells
showed that the general features of the injected cell are
retained although some organelles are distorted. The main
features of the geometry of this neuron are the same from
animal to animal: a single large process runs from the soma
through the neuropil to bifurcate and enter the
contralateral roots. Within the neuropil the main process
gives off long branches (up to 150 micro), but these are
greatly outnumbered by short branches and spines, one or a
few microns in length, which were not appreciated in
previous light microscope studies after injection of Procion
yellow. Serial thin sections of selected areas along the
main process within the neuropil showed that there are
synapses on most of the shorter branches and spines;
occasional synaptic contacts were also made on the main
process itself and on longer branches. At least two
morphologically distinct types of synapse could be
recognized. A minimum estimate of the total number of
synapses on the motor cell is 300, based on their occurrence
in reconstructed segments.},
Doi = {10.1083/jcb.55.1.205},
Key = {fds268355}
}
@article{fds268354,
Author = {Nicholls, JG and Purves, D},
Title = {A comparison of chemical and electrical synaptic
transmission between single sensory cells and a motoneurone
in the central nervous system of the leech.},
Journal = {The Journal of Physiology},
Volume = {225},
Number = {3},
Pages = {637-656},
Year = {1972},
Month = {September},
ISSN = {0022-3751},
url = {http://dx.doi.org/10.1113/jphysiol.1972.sp009961},
Abstract = {In leech ganglia, three sensory cells of different modality
converge on a motoneurone, where they form chemical and
electrical synapses. Each of these synapses behaves in a
characteristic manner and the nature of the transmission
mechanism has significant functional consequences for the
operation of the reflexes. An analysis has been made of the
effects of trains of impulses on synaptic transmission
through these pathways, using frequencies that correspond to
natural firing.1. At the chemical synapse between the
nociceptive sensory cell and the motoneurone, two opposing
events occur: facilitation and depression. Thus, with trains
of impulses, the synaptic potentials first increase in
amplitude and then decrease. The two processes could be
separated by altering the Mg and Ca content of the bathing
fluid. In concentrations of Mg that reduced the amplitude of
a single control chemical synaptic potential, pure
facilitation occurred during a train. Depression
predominated during brief trains in raised concentrations of
Ca, although synaptic potentials were initially larger.
These results suggest that changes in the amount of
transmitter released by each presynaptic action potential
can account for the changes observed in chemical synaptic
transmission.2. In contrast, electrical transmission between
the sensory cell responding to touch and the same
motoneurone did not show facilitation or depression. The
electrical coupling potential in the motoneurone was
relatively constant when the touch cell fired at high or low
frequencies in normal Ringer fluid, high Mg, or high Ca
fluid.3. Further differences between chemical and electrical
synapses were apparent when the preparation was cooled to 4
degrees C. In the cold the latency of chemically evoked
synaptic potentials in the motoneurone increased and their
amplitude declined drastically with repetitive stimulation,
while electrical coupling potentials were unaffected.4. A
brief hyperpolarization of the presynaptic cell by injected
current produced a marked and prolonged increase in
chemically evoked synaptic potentials, but did not influence
electrical synaptic transmission.5. The synapses of the
sensory cell responding to pressure, which are both chemical
and electrical, behaved as expected: the chemical synaptic
potentials showed facilitation and depression while
electrical transmission remained relatively constant.6.
These experiments emphasize the different functional
consequences of electrical or chemical synapses in reflex
pathways for the transmission of signals that arise as a
result of natural sensory stimuli.},
Doi = {10.1113/jphysiol.1972.sp009961},
Key = {fds268354}
}
@article{fds268475,
Author = {McMahan, UJ and Purves, D},
Title = {An electron-microscopic study of a physiologically
identified motoneurone in the leech C.N.S. after injection
of the fluorescent dye Procion yellow.},
Journal = {The Journal of Physiology},
Volume = {222},
Number = {1},
Pages = {64P-66P},
Year = {1972},
Month = {April},
Key = {fds268475}
}
@article{fds268476,
Author = {Nicholls, JG and Purves, D},
Title = {Monosynaptic chemical and electrical connexions between
sensory and motor cells in the central nervous system of the
leech.},
Journal = {The Journal of Physiology},
Volume = {209},
Number = {3},
Pages = {647-667},
Year = {1970},
Month = {August},
url = {http://dx.doi.org/10.1113/jphysiol.1970.sp009184},
Abstract = {The synaptic connexions that underlie three different
segmental shortening reflexes have been traced by recording
intracellularly from individual sensory and motor nerve
cells in the C.N.S. of the leech. The fourteen sensory cells
involved in these reflexes respond specifically to one of
three modalities: touch, pressure, or noxious stimuli
applied to the skin. All three types of sensory neurone give
rise to excitatory synaptic potentials in two large
motoneurones. Each of these motor cells provides excitatory
innervation to the longitudinal muscle fibres of the
opposite side of the segment. The mechanism of synaptic
transmission is, however, different for each type of sensory
cell.1. An impulse in a sensory cell that responds to touch
gives rise to a short-latency depolarizing potential in the
large longitudinal motoneurones by way of an electrical
synapse. This junction rectifies so that excitation can
spread in only one direction (from the sensory to the motor
cell), whereas a hyperpolarizing potential can pass only in
the opposite direction.2. The synaptic potential evoked in
the motoneurone by an action potential in a sensory cell
responding to noxious stimuli can be attributed to the
action of a chemical transmitter agent and has different
properties: the post-synaptic potential arises after a delay
of about 2-4 msec, is abolished by high concentrations of
Mg, and enhanced by high concentrations of Ca. Several lines
of evidence show that this connexion is monosynaptic.3. The
synaptic potential following an impulse in a pressure cell
is produced by both chemical and electrical synaptic
mechanisms. Rectification, similar to that described for the
touch cell, also occurs at this electrical synapse.4. One or
more impulses in any one of the fourteen mechanoreceptor
cells in the ganglion can initiate impulses in the large
longitudinal motoneurones to produce a shortening of the
segment. The contraction is abolished by blocking impulse
initiation in the motoneurones.5. The arborizations of the
sensory cells and the motoneurone within the neuropile have
been studied histologically after injecting a fluorescent
dye. Their processes are intertwined in a highly complex
manner so that the sites of the synaptic junctions cannot be
determined with the resolutions so far achieved.
Nevertheless, taken together the histological and the
electrical results support the idea that individual cells
are connected in a stereotyped pattern and operate by
distinctive mechanisms.6. These findings provide a basis for
studying the functional role of chemical and electrical
synaptic mechanisms in these pathways.},
Doi = {10.1113/jphysiol.1970.sp009184},
Key = {fds268476}
}
%% Articles and Chapters
@article{fds323314,
Author = {Bowling, D and Purves, D},
Title = {A biological basis for musical tonality},
Pages = {205-214},
Booktitle = {Sensory Perception: Mind and Matter},
Publisher = {Springer Vienna},
Year = {2012},
Month = {January},
ISBN = {9783211997505},
url = {http://dx.doi.org/10.1007/978-3-211-99751-2_12},
Abstract = {Like other sensory qualities, the human ability to perceive
tonal sound stimuli has presumably evolved because of its
utility. Although a variety of tonal sounds are present in
the human auditory environment, the vocalizations of other
humans are the most biologically relevant and the most
frequently experienced. It is thus reasonable to assume that
our appreciation of tonal sounds has arisen primarily for
the benefits that accrue from this conspecific information.
It follows that the structure and function of the tonal
sounds produced by the human vocal apparatus may provide the
key to understanding how and why we perceive tonality in
music the way that we do. Here we consider recent evidence
that bears on this idea.},
Doi = {10.1007/978-3-211-99751-2_12},
Key = {fds323314}
}
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