Publications of Miguel A Nicolelis :chronological combined listing:
%% Papers Published
@article{fds114979,
Author = {JM Carmena and MA Lebedev and RE Crist and JE O'Doherty and DM Santucci and DF Dimitrov and PG Patil and CS Henriquez and MA Nicolelis},
Title = {Learning to control a brain-machine interface for reaching
and grasping by primates.},
Journal = {PLoS biology, United States},
Volume = {1},
Number = {2},
Pages = {E42},
Year = {2003},
Month = {November},
ISSN = {1545-7885},
Keywords = {Animals • Arm • Artificial Intelligence •
Behavior, Animal • Biomechanics* • Biophysics*
• Brain • Brain Mapping • Electromyography
• Electrophysiology • Female • Hand •
Hand Strength* • Learning • Macaca • Models,
Neurological • Models, Statistical • Models,
Theoretical • Motor Activity • Motor Cortex •
Movement • Neurons • Primates • Psychomotor
Performance • Robotics • Somatosensory Cortex
• Space Perception • Time Factors •
metabolism • methods • pathology • pathology*
• physiology*},
Abstract = {Reaching and grasping in primates depend on the coordination
of neural activity in large frontoparietal ensembles. Here
we demonstrate that primates can learn to reach and grasp
virtual objects by controlling a robot arm through a
closed-loop brain-machine interface (BMIc) that uses
multiple mathematical models to extract several motor
parameters (i.e., hand position, velocity, gripping force,
and the EMGs of multiple arm muscles) from the electrical
activity of frontoparietal neuronal ensembles. As single
neurons typically contribute to the encoding of several
motor parameters, we observed that high BMIc accuracy
required recording from large neuronal ensembles. Continuous
BMIc operation by monkeys led to significant improvements in
both model predictions and behavioral performance. Using
visual feedback, monkeys succeeded in producing robot
reach-and-grasp movements even when their arms did not move.
Learning to operate the BMIc was paralleled by functional
reorganization in multiple cortical areas, suggesting that
the dynamic properties of the BMIc were incorporated into
motor and sensory cortical representations.},
Key = {fds114979}
}
@article{fds114981,
Author = {MC Wiest and MA Nicolelis},
Title = {Behavioral detection of tactile stimuli during 7-12 Hz
cortical oscillations in awake rats.},
Journal = {Nature neuroscience, United States},
Volume = {6},
Number = {9},
Pages = {913-4},
Year = {2003},
Month = {September},
ISSN = {1097-6256},
Keywords = {Animals • Behavior, Animal • Biological Clocks
• Cerebral Cortex • Female • Immobilization
• Physical Stimulation • Rats • Rats,
Long-Evans • Reaction Time • Touch •
Vibrissae • Wakefulness • methods •
physiology • physiology*},
Abstract = {Prominent 7-12 Hz oscillations in the primary somatosensory
cortex (S1) of awake but immobile rats might represent a
seizure-like state in which neuronal burst firing renders
animals unresponsive to incoming tactile stimuli; others
have proposed that these oscillations are analogous to human
mu rhythm. To test whether rats can respond to tactile
stimuli during 7-12 Hz oscillatory activity, we trained
head-immobilized awake animals to indicate whether they
could detect the occurrence of transient whisker deflections
while we recorded local field potentials (LFPs) from
microelectrode arrays implanted bilaterally in the S1
whisker representation area. They responded rapidly and
reliably, suggesting that this brain rhythm represents
normal physiological activity that does not preclude
perception.},
Key = {fds114981}
}
@article{fds114982,
Author = {MA Nicolelis and D Dimitrov and JM Carmena and R Crist and G Lehew and JD
Kralik, SP Wise},
Title = {Chronic, multisite, multielectrode recordings in macaque
monkeys.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America, United States},
Volume = {100},
Number = {19},
Pages = {11041-6},
Year = {2003},
Month = {September},
ISSN = {0027-8424},
Keywords = {Action Potentials • Animals • Cerebral Cortex
• Electrodes • Female • Macaca mulatta •
Male • physiology*},
Abstract = {A paradigm is described for recording the activity of single
cortical neurons from awake, behaving macaque monkeys. Its
unique features include high-density microwire arrays and
multichannel instrumentation. Three adult rhesus monkeys
received microwire array implants, totaling 96-704
microwires per subject, in up to five cortical areas,
sometimes bilaterally. Recordings 3-4 weeks after
implantation yielded 421 single neurons with a mean
peak-to-peak voltage of 115 +/- 3 microV and a
signal-to-noise ratio of better than 5:1. As many as 247
cortical neurons were recorded in one session, and at least
58 neurons were isolated from one subject 18 months after
implantation. This method should benefit neurophysiological
investigation of learning, perception, and sensorimotor
integration in primates and the development of
neuroprosthetic devices.},
Key = {fds114982}
}
@article{fds114980,
Author = {MS Matell and WH Meck and MA Nicolelis},
Title = {Interval timing and the encoding of signal duration by
ensembles of cortical and striatal neurons.},
Journal = {Behavioral neuroscience, United States},
Volume = {117},
Number = {4},
Pages = {760-73},
Year = {2003},
Month = {August},
ISSN = {0735-7044},
Keywords = {Animals • Cerebral Cortex • Conditioning, Operant
• Corpus Striatum • Discrimination Learning*
• Male • Neurons • Rats • Rats,
Sprague-Dawley • Time Perception* • physiology
• physiology*},
Abstract = {This study investigated the firing patterns of striatal and
cortical neurons in rats in a temporal generalization task.
Striatal and cortical ensembles were recorded in rats
trained to lever press at 2 possible criterion durations (10
s or 40 s from tone onset). Twenty-two percent of striatal
and 15% of cortical cells had temporally specific
modulations in their firing rate, firing at a significantly
different rate around 10 s compared with 40 s. On 80% of
trials, a post hoc analysis of the trial-by-trial
consistency of the firing rates of an ensemble of neurons
predicted whether a spike train came from a time window
around 10 s versus around 40 s. Results suggest that
striatal and cortical neurons encode specific durations in
their firing rate and thereby serve as components of a
neural circuit used to represent duration.},
Key = {fds114980}
}
@article{fds114978,
Author = {MA Nicolelis},
Title = {Brain-machine interfaces to restore motor function and probe
neural circuits.},
Journal = {Nature reviews. Neuroscience, England},
Volume = {4},
Number = {5},
Pages = {417-22},
Year = {2003},
Month = {May},
ISSN = {1471-003X},
Keywords = {Animals • Humans • Motor Activity • Motor
Cortex • Nerve Net • Neuronal Plasticity •
Paralysis • Prostheses and Implants* • pathology
• physiology • physiology* •
therapy},
Key = {fds114978}
}
@article{fds114972,
Author = {I Obeid and JC Morizio and KA Moxon and MA Nicolelis and PD
Wolf},
Title = {Two multichannel integrated circuits for neural recording
and signal processing.},
Journal = {IEEE transactions on bio-medical engineering, United
States},
Volume = {50},
Number = {2},
Pages = {255-8},
Year = {2003},
Month = {February},
ISSN = {0018-9294},
Keywords = {Action Potentials • Amplifiers* • Animals •
Artifacts • Electrodes, Implanted •
Electrophysiology • Equipment Design • Feasibility
Studies • Haplorhini • Miniaturization •
Neurons • Pilot Projects • Quality Control •
Rats • Semiconductors • Somatosensory Cortex
• instrumentation* • physiology •
physiology*},
Abstract = {We have developed, manufactured, and tested two analog CMOS
integrated circuit "neurochips" for recording from arrays of
densely packed neural electrodes. Device A is a 16-channel
buffer consisting of parallel noninverting amplifiers with a
gain of 2 V/V. Device B is a 16-channel two-stage analog
signal processor with differential amplification and
high-pass filtering. It features selectable gains of 250 and
500 V/V as well as reference channel selection. The
resulting amplifiers on Device A had a mean gain of 1.99 V/V
with an equivalent input noise of 10 microV(rms). Those on
Device B had mean gains of 53.4 and 47.4 dB with a high-pass
filter pole at 211 Hz and an equivalent input noise of 4.4
microV(rms). Both devices were tested in vivo with electrode
arrays implanted in the somatosensory cortex.},
Key = {fds114972}
}
@article{fds114947,
Author = {MA Nicolelis and EE Fanselow},
Title = {Dynamic shifting in thalamocortical processing during
different behavioural states.},
Journal = {Philosophical transactions of the Royal Society of London.
Series B, Biological sciences, England},
Volume = {357},
Number = {1428},
Pages = {1753-8},
Year = {2002},
Month = {December},
ISSN = {0962-8436},
Keywords = {Animals • Behavior, Animal • Cerebral Cortex
• Models, Neurological • Neural Pathways •
Rats • Thalamus • physiology •
physiology*},
Abstract = {Recent experiments in our laboratory have indicated that as
rats shift the behavioural strategy employed to explore
their surrounding environment, there is a parallel change in
the physiological properties of the neuronal ensembles that
define the main thalamocortical loop of the trigeminal
somatosensory system. Based on experimental evidence from
several laboratories, we propose that this concurrent shift
in behavioural strategy and thalamocortical physiological
properties provides rats with an efficient way to optimize
either the detection or analysis of complex tactile
stimuli.},
Key = {fds114947}
}
@article{fds114885,
Author = {MA Nicolelis},
Title = {The amazing adventures of robotrat.},
Journal = {Trends Cogn Sci},
Volume = {6},
Number = {11},
Pages = {449-450},
Year = {2002},
Month = {November},
ISSN = {1364-6613},
Abstract = {By using electrical brain stimulation to deliver both
'virtual' tactile cues and rewards to freely roaming rats,
Talwar et al. have been able to instruct animals remotely to
navigate through complex mazes and natural environments they
have never visited before. These results provide both an
elegant alternative way to train animals and a new approach
to study basic neurophysiological principles of animal
navigation.},
Key = {fds114885}
}
@article{fds114938,
Author = {MA Nicolelis and S Ribeiro},
Title = {Multielectrode recordings: the next steps.},
Journal = {Current opinion in neurobiology, England},
Volume = {12},
Number = {5},
Pages = {602-6},
Year = {2002},
Month = {October},
ISSN = {0959-4388},
Keywords = {Animals • Electrodes • Electrophysiology •
Nervous System Physiology* • Neurons • methods*
• physiology},
Abstract = {At present, a growing number of laboratories are acquiring
the capability of simultaneously monitoring the
extracellular activity of over a hundred single neurons in
both anaesthetized and awake animals. This paradigm, known
as multielectrode recordings, is changing the face of
systems neuroscience by allowing, for the first time, the
visualization of the function of entire neural circuits at
work. Current methods of multielectrode recording employ
state of the art technologies; two potential new avenues of
research will likely emerge from the further development of
these experimental paradigms.},
Key = {fds114938}
}
@article{fds114941,
Author = {MA Nicolelis and JK Chapin},
Title = {Controlling robots with the mind.},
Journal = {Scientific American, United States},
Volume = {287},
Number = {4},
Pages = {46-53},
Year = {2002},
Month = {October},
ISSN = {0036-8733},
Keywords = {Action Potentials • Animals • Aotidae • Brain
• Electrodes, Implanted • Electronics •
Electrophysiology • Female • Miniaturization
• Motor Cortex • Motor Neurons • Nervous
System Diseases • Paralysis • Prostheses and
Implants • Rats • Robotics • instrumentation*
• physiology • physiology* •
therapy},
Key = {fds114941}
}
@article{fds114881,
Author = {DB Katz and MA Nicolelis and SA Simon},
Title = {Gustatory processing is dynamic and distributed.},
Journal = {Current opinion in neurobiology, England},
Volume = {12},
Number = {4},
Pages = {448-54},
Year = {2002},
Month = {August},
ISSN = {0959-4388},
Keywords = {Action Potentials • Amygdala • Animals •
Brain • Brain Stem • Cerebral Cortex •
Hypothalamus • Models, Neurological • Neural
Pathways • Somatosensory Cortex • Taste •
Taste Buds • Thalamus • Time Factors •
anatomy & histology • physiology •
physiology*},
Abstract = {The process of gustatory coding consists of neural responses
that provide information about the quantity and quality of
food, its generalized sensation, its hedonic value, and
whether it should be swallowed. Many of the models presently
used to analyze gustatory signals are static in that they
use the average neural firing rate as a measure of activity
and are unimodal in the sense they are thought to only
involve chemosensory information. We have recently
elaborated upon a dynamic model of gustatory coding that
involves interactions between neurons in single as well as
in spatially separate, gustatory and somatosensory regions.
We propose that the specifics of gustatory responses grow
not only out of information ascending from taste receptor
cells, but also from the cycling of information around a
massively interconnected system.},
Key = {fds114881}
}
@article{fds114937,
Author = {MA Nicolelis and EE Fanselow},
Title = {Thalamocortical [correction of Thalamcortical] optimization
of tactile processing according to behavioral
state.},
Journal = {Nature neuroscience, United States},
Volume = {5},
Number = {6},
Pages = {517-23},
Year = {2002},
Month = {June},
ISSN = {1097-6256},
Keywords = {Afferent Pathways • Animals • Behavior, Animal
• Efferent Pathways • Models, Neurological •
Rats • Somatosensory Cortex • Thalamus •
Touch • physiology • physiology*},
Abstract = {We propose a conceptual model that describes the operation
of the main thalamocortical loop of the rat somatosensory
system. According to this model, the asynchronous
convergence of ascending and descending projections
dynamically alters the physiological properties of thalamic
neurons in the ventral posterior medial (VPM) nucleus as
rats shift between three behavioral states. Two of these
states are characterized by distinct modes of rhythmic
whisker movements. We posit that these simultaneous shifts
in exploratory behavioral strategy and in the physiological
properties of VPM neurons allow rats to either (i) optimize
the detection of stimuli that are novel or difficult to
sense or (ii) process complex patterns of multi-whisker
stimulation.},
Key = {fds114937}
}
@article{fds114882,
Author = {MA Nicolelis},
Title = {Depression at thalamocortical synapses: the key for cortical
neuronal adaptation?},
Journal = {Neuron, United States},
Volume = {34},
Number = {3},
Pages = {331-2},
Year = {2002},
Month = {April},
ISSN = {0896-6273},
Keywords = {Adaptation, Physiological • Animals • Cerebral
Cortex • Neuronal Plasticity* • Rats •
Synapses • Synaptic Transmission • Thalamus •
Touch • cytology • metabolism* •
physiology*},
Abstract = {Neuronal adaptation to repetitive sensory stimuli is
ubiquitous in the mammalian cortex. Despite its prevalence,
the cellular mechanisms underlying this basic physiological
property remain a matter of dispute. In this issue of
Neuron, Chung et al. provide conclusive evidence that
depression of thalamocortical synapses may play a
significant role in the expression of neuronal adaptation in
the rat somatosensory cortex.},
Key = {fds114882}
}
@article{fds114889,
Author = {DB Katz and SA Simon and MA Nicolelis},
Title = {Taste-specific neuronal ensembles in the gustatory cortex of
awake rats.},
Journal = {The Journal of neuroscience : the official journal of the
Society for Neuroscience, United States},
Volume = {22},
Number = {5},
Pages = {1850-7},
Year = {2002},
Month = {March},
ISSN = {1529-2401},
Keywords = {Action Potentials • Animals • Cerebral Cortex
• Citric Acid • Electrodes, Implanted •
Electrophysiology • Female • Male • Neurons
• Nicotine • Quinine • Rats • Rats,
Long-Evans • Reaction Time • Sodium Chloride
• Statistics • Stimulation, Chemical •
Sucrose • Taste • Tongue • Wakefulness •
cytology • drug effects • pharmacology •
physiology • physiology*},
Abstract = {In gustatory cortex, single-neuron activity reflects the
multimodal processing of taste stimuli. Little is known,
however, about the interactions between gustatory cortical
(GC) neurons during tastant processing. Here, these
interactions were characterized. It was found that 36% (85
of 237) of neuron pairs, including many (61%) in which one
or both single units were not taste specific, produced
significant cross-correlations (CCs) to a subset of tastants
across a hundreds of milliseconds timescale. Significant CCs
arose from the coupling between the firing rates of neurons
as those rates changed through time. Such coupling
significantly increased the amount of tastant-specific
information contained in ensembles. These data suggest that
taste-specific GC assemblies may transiently form and
coevolve on a behaviorally appropriate timescale,
contributing to rats' ability to discriminate
tastants.},
Key = {fds114889}
}
@article{fds114883,
Author = {MG Shuler and DJ Krupa and MA Nicolelis},
Title = {Integration of bilateral whisker stimuli in rats: role of
the whisker barrel cortices.},
Journal = {Cerebral cortex (New York, N.Y. : 1991), United
States},
Volume = {12},
Number = {1},
Pages = {86-97},
Year = {2002},
Month = {January},
ISSN = {1047-3211},
Keywords = {Animals • Behavior, Animal • Electric Stimulation
• Electrodes, Implanted • Functional Laterality
• Male • Physical Stimulation • Psychomotor
Performance • Rats • Rats, Long-Evans •
Somatosensory Cortex • Vibrissae • innervation*
• physiology • physiology*},
Abstract = {Recently, we demonstrated that neural responses within the
whisker region of the primary somatosensory cortex (SIw) of
rats are profoundly influenced by the spatiotemporal
attributes of ipsilateral, as well as contralateral, whisker
stimuli. As inactivation of one SIw eliminates in the intact
SIw both ipsilaterally evoked responses and the influence of
ipsilateral stimulation on contralaterally evoked activity,
we proposed that interhemispheric interactions between the
SIws may be important for integrating bilateral whisker
information. To test whether rats can recognize the
bilateral nature of a whisker stimulus, we developed a
tactile discrimination task that required rats to conjointly
determine distances to a left and a right discriminandum as
equidistant or non-equidistant using only their facial
whiskers. All rats trained in this task achieved performance
levels indicative of an ability to integrate bilateral
whisker information. Testing during unilateral, as well as
bilateral, inactivation of the SIws indicated that rats rely
on both SIws for detecting the bilateral nature of a whisker
stimulus. Rats were unable to perform the task without both
sets of whiskers, a fact that indicates that the whiskers
(and not other modalities) were used to perform this task.
The findings presented here indicate that rats can solve a
task that requires the conjoint detection of left and right
whisker-mediated distance information and implicate the SIws
as central to this ability.},
Key = {fds114883}
}
@article{fds114890,
Title = {Nicolelis MAL, Fanselow EE (2002) Dynamic shifting in
thalamocortical processing during different behavior. Phil
Trans R Soc Lond B 357: 1753-1758.},
Year = {2002},
Key = {fds114890}
}
@article{fds114936,
Author = {A Das and JG Franca and R Gattass and JH Kaas and MA Nicolelis and C
Timo-Iaria, CD Vargas and NM Weinberger and E Volchan},
Title = {The brain decade in debate: VI. Sensory and motor maps:
dynamics and plasticity.},
Journal = {Brazilian journal of medical and biological research =
Revista brasileira de pesquisas médicas e biológicas /
Sociedade Brasileira de Biofísica ... [et al.],
Brazil},
Volume = {34},
Number = {12},
Pages = {1497-508},
Year = {2001},
Month = {December},
ISSN = {0100-879X},
Keywords = {Animals • Brain Mapping* • Cerebral Cortex •
Emotions • Humans • Learning • Motor Cortex
• Neuronal Plasticity • Neurons •
Somatosensory Cortex • Visual Perception •
cytology • physiology • physiology*},
Abstract = {This article is an edited transcription of a virtual
symposium promoted by the Brazilian Society of Neuroscience
and Behavior (SBNeC). Although the dynamics of sensory and
motor representations have been one of the most studied
features of the central nervous system, the actual
mechanisms of brain plasticity that underlie the dynamic
nature of sensory and motor maps are not entirely unraveled.
Our discussion began with the notion that the processing of
sensory information depends on many different cortical
areas. Some of them are arranged topographically and others
have non-topographic (analytical) properties. Besides a
sensory component, every cortical area has an efferent
output that can be mapped and can influence motor behavior.
Although new behaviors might be related to modifications of
the sensory or motor representations in a given cortical
area, they can also be the result of the acquired ability to
make new associations between specific sensory cues and
certain movements, a type of learning known as conditioning
motor learning. Many types of learning are directly related
to the emotional or cognitive context in which a new
behavior is acquired. This has been demonstrated by
paradigms in which the receptive field properties of
cortical neurons are modified when an animal is engaged in a
given discrimination task or when a triggering feature is
paired with an aversive stimulus. The role of the
cholinergic input from the nucleus basalis to the neocortex
was also highlighted as one important component of the
circuits responsible for the context-dependent changes that
can be induced in cortical maps.},
Key = {fds114936}
}
@article{fds114939,
Author = {EE Fanselow and K Sameshima and LA Baccala and MA
Nicolelis},
Title = {Thalamic bursting in rats during different awake behavioral
states.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America, United States},
Volume = {98},
Number = {26},
Pages = {15330-5},
Year = {2001},
Month = {December},
ISSN = {0027-8424},
Keywords = {Animals • Behavior, Animal* • Electric Stimulation
• Neurons • Rats • Thalamus •
Wakefulness* • physiology • physiology*},
Abstract = {Thalamic neurons have two firing modes: tonic and bursting.
It was originally suggested that bursting occurs only during
states such as slow-wave sleep, when little or no
information is relayed by the thalamus. However, bursting
occurs during wakefulness in the visual and somatosensory
thalamus, and could theoretically influence sensory
processing. Here we used chronically implanted electrodes to
record from the ventroposterior medial thalamic nucleus
(VPM) and primary somatosensory cortex (SI) of awake, freely
moving rats during different behaviors. These behaviors
included quiet immobility, exploratory whisking
(large-amplitude whisker movements), and whisker twitching
(small-amplitude, 7- to 12-Hz whisker movements). We
demonstrated that thalamic bursting appeared during the
oscillatory activity occurring before whisker twitching
movements, and continued throughout the whisker twitching.
Further, thalamic bursting occurred during whisker twitching
substantially more often than during the other behaviors,
and a neuron was most likely to respond to a stimulus if a
burst occurred approximately 120 ms before the stimulation.
In addition, the amount of cortical area activated was
similar to that during whisking. However, when SI was
inactivated by muscimol infusion, whisker twitching was
never observed. Finally, we used a statistical technique
called partial directed coherence to identify the direction
of influence of neural activity between VPM and SI, and
observed that there was more directional coherence from SI
to VPM during whisker twitching than during the other
behaviors. Based on these findings, we propose that during
whisker twitching, a descending signal from SI triggers
thalamic bursting that primes the thalamocortical loop for
enhanced signal detection during the whisker twitching
behavior.},
Key = {fds114939}
}
@article{fds114935,
Author = {AA Ghazanfar and DJ Krupa and MA Nicolelis},
Title = {Role of cortical feedback in the receptive field structure
and nonlinear response properties of somatosensory thalamic
neurons.},
Journal = {Experimental brain research. Experimentelle Hirnforschung.
Expérimentation cérébrale, Germany},
Volume = {141},
Number = {1},
Pages = {88-100},
Year = {2001},
Month = {November},
ISSN = {0014-4819},
Keywords = {Animals • Feedback • Female • Neurons •
Nonlinear Dynamics • Rats • Rats, Long-Evans
• Reaction Time • Somatosensory Cortex •
Thalamus • Ventral Thalamic Nuclei • Vibrissae
• physiology • physiology*},
Abstract = {Previous studies have suggested that the descending pathway
from the primary somatosensory (SI) cortex to the ventral
posterior nucleus of the thalamus has only a mild
facilitative influence over thalamic neurons. Given the
large numbers of corticothalamic terminations within the rat
somatosensory thalamus and their complex topography, we
sought to examine the role of corticothalamic feedback in
the genesis of spatiotemporal receptive fields and the
integration of complex tactile stimuli in the thalamus. By
combining focal cortical inactivation (produced by
microinjection of the GABA(A) agonist muscimol), with
chronic multielectrode recordings, we observed that feedback
from the rat SI cortex has multiple influences on its
primary thalamic relay, the ventral posterior medial (VPM)
nucleus. Our data demonstrate that, when single-whisker
stimuli were used, the elimination of cortical feedback
caused significant changes in the spatiotemporal structure
of the receptive fields of VPM neurons. Cortical feedback
also accounted for the nonlinear summation of VPM neural
responses to simultaneously stimulated whiskers, in effect
"linearizing" the responses. These results argue that the
integration and transmission of tactile information through
VPM are strongly influenced by the state of SI
cortex.},
Key = {fds114935}
}
@article{fds114933,
Author = {JD Kralik and DF Dimitrov and DJ Krupa and DB Katz and D Cohen and MA
Nicolelis},
Title = {Techniques for long-term multisite neuronal ensemble
recordings in behaving animals.},
Journal = {Methods (San Diego, Calif.), United States},
Volume = {25},
Number = {2},
Pages = {121-50},
Year = {2001},
Month = {October},
ISSN = {1046-2023},
Keywords = {Animals • Behavior, Animal* • Brain •
Electrodes • Electrophysiology • Mice •
Multivariate Analysis • Neurology • Neurons •
Neurosurgery • Rats • Time Factors • methods*
• pathology • physiology*},
Abstract = {Advances in our understanding of neural systems will go hand
in hand with improvements in the experimental techniques
used to study these systems. This article describes a series
of methodological developments aimed at enhancing the power
of the methods needed to record simultaneously from
populations of neurons over broad regions of the brain in
awake, behaving animals. First, our laboratory has made many
advances in electrode design, including movable bundle and
array electrodes and smaller electrode assemblies. Second,
to perform longer and more complex multielectrode
implantation surgeries in primates, we have modified our
surgical procedures by employing comprehensive physiological
monitoring akin to human neuroanesthesia. We have also
developed surgical implantation techniques aimed at
minimizing brain tissue damage and facilitating penetration
of the cortical surface. Third, we have integrated new
technologies into our neural ensemble, stimulus and
behavioral recording experiments to provide more detailed
measurements of experimental variables. Finally, new data
analytical techniques are being used in the laboratory to
analyze increasingly large quantities of
data.},
Key = {fds114933}
}
@article{fds114884,
Author = {DJ Krupa and MS Matell and AJ Brisben and LM Oliveira and MA
Nicolelis},
Title = {Behavioral properties of the trigeminal somatosensory system
in rats performing whisker-dependent tactile
discriminations.},
Journal = {The Journal of neuroscience : the official journal of the
Society for Neuroscience, United States},
Volume = {21},
Number = {15},
Pages = {5752-63},
Year = {2001},
Month = {August},
ISSN = {1529-2401},
Keywords = {Afferent Pathways • Animals • Behavior, Animal
• Discrimination Learning • Electrodes, Implanted
• Facial Nerve • GABA Agonists • Male •
Mechanoreceptors • Muscimol • Physical Stimulation
• Rats • Rats, Long-Evans • Receptors, GABA-A
• Somatosensory Cortex • Touch • Trigeminal
Nerve • Vibrissae • administration & dosage •
agonists • drug effects • innervation •
instrumentation • pharmacology • physiology •
physiology*},
Abstract = {To address several fundamental questions regarding how
multiwhisker tactile stimuli are integrated and processed by
the trigeminal somatosensory system, a novel behavioral task
was developed that required rats to discriminate the width
of either a wide or narrow aperture using only their large
mystacial vibrissae. Rats quickly acquired this task and
could accurately discriminate between apertures of very
similar width. Accurate discriminations required a large
number of intact facial whiskers. Systematic removal of
individual whiskers caused a decrease in performance that
was directly proportional to the number of whiskers removed,
indicating that tactile information from multiple whiskers
is integrated as rats gauge aperture width. In different
groups of rats, different sets of whiskers were removed in
patterns that preferentially left whisker rows or whisker
arcs intact. These different whisker removals caused similar
decreases in performance, indicating that individual
whiskers within the vibrissal array are functionally
equivalent during performance of this task. Lesions of the
barrel cortex abolished the ability of rats to discriminate,
demonstrating that this region is critically involved in
this tactile behavior. Interestingly, sectioning the facial
nerve, which abolished whisker movements, did not affect the
ability to perform accurate discriminations, indicating that
active whisker movements are not necessary for accurate
performance of the task. Collectively, these results
indicate that the trigeminal somatosensory system forms
internal representations of external stimuli (in this case,
aperture width) by integrating tactile input from many
functionally equivalent facial whiskers and that the
vibrissal array can function as a fine-grained distance
detector without active whisker movements.},
Key = {fds114884}
}
@article{fds114940,
Author = {MG Shuler and DJ Krupa and MA Nicolelis},
Title = {Bilateral integration of whisker information in the primary
somatosensory cortex of rats.},
Journal = {The Journal of neuroscience : the official journal of the
Society for Neuroscience, United States},
Volume = {21},
Number = {14},
Pages = {5251-61},
Year = {2001},
Month = {July},
ISSN = {1529-2401},
Keywords = {Analysis of Variance • Animals • Electrodes,
Implanted • Evoked Potentials • Female •
Functional Laterality • Microinjections • Muscimol
• Neurons • Physical Stimulation • Rats
• Rats, Long-Evans • Reaction Time •
Somatosensory Cortex • Touch • Vibrissae •
administration & dosage • cytology • drug effects
• innervation • physiology •
physiology*},
Abstract = {The isomorphic representation of the contralateral whisker
pad in the rodent cerebral cortex has served as a canonical
example in primary somatosensory areas that the
contralateral body surface is spatially represented as a
topographic map. By characterizing responses evoked by
multiwhisker stimuli, we provide direct evidence that the
whisker region of the rat primary somatosensory cortex (SI)
integrates information from both contralateral and
ipsilateral whisker pads. The proportions of SI neurons
responsive to ipsilateral whisker stimuli, as well as their
response probabilities, increased with the number of
ipsilateral whiskers stimulated. Under bilateral whisker
stimulation, the responses of 95% of neurons recorded were
affected by stimulation of ipsilateral whiskers.
Contralateral tactile responses of SI neurons were
profoundly influenced by preceding ipsilateral stimuli and
vice versa. This effect depended on both the spatial
location and the relative timing of bilateral whisker
stimuli, leading to both spatial and temporal asymmetries of
interaction. Bilateral whisker stimulation resulted in only
modest changes in evoked response latency. Previous
ipsilateral stimulation was also shown to affect tactile
responses evoked by later ipsilateral stimuli. Inactivation
of the opposite SI abolished ipsilaterally evoked responses
as well as their influence on subsequently evoked
contralateral responses in the intact SI. Based on these
results, we conclude that the rat SI integrates information
from both whisker pads and propose that such interactions
may underlie the ability of rats to discriminate bilateral
tactile stimuli.},
Key = {fds114940}
}
@article{fds114886,
Author = {DB Katz and SA Simon and MA Nicolelis},
Title = {Dynamic and multimodal responses of gustatory cortical
neurons in awake rats.},
Journal = {The Journal of neuroscience : the official journal of the
Society for Neuroscience, United States},
Volume = {21},
Number = {12},
Pages = {4478-89},
Year = {2001},
Month = {June},
ISSN = {1529-2401},
Keywords = {Action Potentials • Analysis of Variance • Animals
• Cerebral Cortex • Citric Acid • Electrodes,
Implanted • Female • Male • Microelectrodes
• Neurons • Nicotine • Quinine • Rats
• Rats, Long-Evans • Reaction Time • Signal
Processing, Computer-Assisted • Sodium Chloride •
Somatosensory Cortex • Stimulation, Chemical •
Sucrose • Taste • Wakefulness •
classification • pharmacology • physiology •
physiology*},
Abstract = {To investigate the dynamic aspects of gustatory activity, we
recorded the responses of small ensembles of cortical
neurons to tastants administered to awake rats. Multiple
trials of each tastant were delivered during recordings made
in oral somatosensory (SI) and gustatory cortex (GC). When
integrated tastant responses (firing rates averaged across
2.5 sec) were compared with water responses, 14.4% (13/90)
of the GC neurons responded in a taste-specific manner. When
time was considered as a source of information, however, the
incidence of taste-specific firing increased: as many as 41%
(37/90) of the recorded GC neurons exhibited taste-specific
patterns of response. For 17% of the neurons identified as
responding with taste-specific patterns, the stimulus that
caused the most significant response was a function of the
time since stimulus delivery. That is, a single neuron might
respond most strongly to one tastant in the first 500 msec
of a response and then respond most strongly to another
tastant later in the response. Further analysis of the time
courses of GC and SI cortical neural responses revealed that
modulations of GC firing rate arose from three separable
processes: early somatosensory input (less than
approximately 0.2 sec post-stimulus), later chemosensory
input ( approximately 0.2-1 sec), and delayed somatosensory
input related to orofacial responses (more than
approximately 1.0 sec). These data demonstrate that sensory
information is available in the time course of GC responses
and suggest the viability of views of gustatory processing
that treat the temporal structure of cortical responses as
an integral part of the neural code.},
Key = {fds114886}
}
@article{fds114942,
Author = {AA Ghazanfar and MA Nicolelis},
Title = {Feature article: the structure and function of dynamic
cortical and thalamic receptive fields.},
Journal = {Cerebral cortex (New York, N.Y. : 1991), United
States},
Volume = {11},
Number = {3},
Pages = {183-93},
Year = {2001},
Month = {March},
ISSN = {1047-3211},
Keywords = {Animals • Auditory Pathways • Geniculate Bodies
• Humans • Somatosensory Cortex • Ventral
Thalamic Nuclei • Visual Cortex • Visual Fields
• Visual Pathways • physiology*},
Abstract = {Under natural conditions, animals must process
spatiotemporally complex signals in order to guide adaptive
behavior. It follows that the response properties of neurons
should reflect the dynamic nature of such signals. Recently,
several studies have demonstrated the existence of
time-varying receptive fields in the auditory, visual and
somatosensory thalamocortical pathways. The characteristics
of these receptive fields suggest that they are constrained
by the need to actively interpret time-varying stimuli.
Here, we review these studies, the possible functions of
these receptive fields, and how they might be generated in
the thalamocortical pathway.},
Key = {fds114942}
}
@article{fds114888,
Author = {DJ Krupa and AJ Brisben and MA Nicolelis},
Title = {A multi-channel whisker stimulator for producing
spatiotemporally complex tactile stimuli.},
Journal = {Journal of neuroscience methods, Netherlands},
Volume = {104},
Number = {2},
Pages = {199-208},
Year = {2001},
Month = {January},
ISSN = {0165-0270},
Keywords = {Animals • Female • Neurons • Physical
Stimulation • Rats • Rats, Long-Evans •
Reaction Time • Somatosensory Cortex • Touch
• Ventral Thalamic Nuclei • Vibrissae •
innervation* • instrumentation* • methods* •
physiology • physiology*},
Abstract = {A system is described that delivers complex, biologically
realistic, tactile stimuli to the rat's facial whisker pad
by independently stimulating up to 16 individual facial
whiskers in a flexible yet highly controlled and repeatable
manner. The system is technically simple and inexpensive to
construct. The system consists of an array of 16
miniature-solenoid driven actuators that are attached to 16
individual facial whiskers via very small (130 microm dia.)
Teflon-coated stainless steel wires. When individual
solenoids are energized, the wire is rapidly retracted,
resulting in a deflection of individual whiskers. The rise
time of deflection is approx. 1 mm/ms. Repeatable
stimulation of individual whiskers can be achieved without
touching adjacent whiskers, thereby allowing a very high
density of stimulators to be attached within the spatially
restricted region of the facial whisker pad. Complex
patterns of whisker stimulation (designed to mimic
biologically realistic stimuli) are delivered to the whisker
pad by activating individual solenoid actuators in precisely
controlled temporal patterns. These stimulations can be
combined with multi-electrode single-unit ensemble
recordings at multiple sites within the rat trigeminal
somatosensory system. Analysis of neuronal population
responses to these complex stimuli is intended to examine
how the trigeminal somatosensory system encodes and
processes spatiotemporally complex stimuli.},
Key = {fds114888}
}
@article{fds114891,
Author = {MA Nicolelis},
Title = {Actions from thoughts.},
Journal = {Nature, England},
Volume = {409},
Number = {6818},
Pages = {403-7},
Year = {2001},
Month = {January},
ISSN = {0028-0836},
Keywords = {Brain* • Cochlear Implants • Computing
Methodologies* • Epilepsy • Humans • Motor
Activity • Therapy, Computer-Assisted* •
User-Computer Interface • physiology* •
therapy},
Key = {fds114891}
}
@article{fds114880,
Title = {Katz DB, Simon SA, Nicolelis MAL (2001) Electrophysiological
studies of gustation in awake rats. In: Methods in
Chemosensory Research (Methods and New Frontiers in
Neuroscience Series, M.A.L. Nicolelis and S.A. Simon, eds.)
CRC Press, pp. 339-357.},
Year = {2001},
Key = {fds114880}
}
@article{fds114934,
Title = {Nicolelis MAL. Actions from thoughts. Nature. 2001 Jan
18;409 Suppl:403-407.},
Year = {2001},
Key = {fds114934}
}
@article{fds114887,
Author = {MA Nicolelis and M Shuler},
Title = {Thalamocortical and corticocortical interactions in the
somatosensory system.},
Journal = {Progress in brain research, Netherlands},
Volume = {130},
Pages = {90-110},
Year = {2001},
ISSN = {0079-6123},
Keywords = {Animals • Cerebral Cortex • Feedback • Humans
• Somatosensory Cortex • Synaptic Transmission
• Thalamus • Touch • Vibrissae •
physiology • physiology*},
Key = {fds114887}
}
@article{fds114958,
Author = {J Wessberg and CR Stambaugh and JD Kralik and PD Beck and M Laubach and JK
Chapin, J Kim and SJ Biggs and MA Srinivasan and MA
Nicolelis},
Title = {Real-time prediction of hand trajectory by ensembles of
cortical neurons in primates.},
Journal = {Nature, ENGLAND},
Volume = {408},
Number = {6810},
Pages = {361-5},
Year = {2000},
Month = {November},
ISSN = {0028-0836},
Keywords = {Animals • Aotus trivirgatus • Arm •
Artificial Limbs* • Brain Mapping • Cerebral
Cortex • Frontal Lobe • Motor Activity •
Motor Cortex • Motor Neurons • Neural Conduction
• Parietal Lobe • Robotics* • Signal
Transduction • physiology • physiology*},
Abstract = {Signals derived from the rat motor cortex can be used for
controlling one-dimensional movements of a robot arm. It
remains unknown, however, whether real-time processing of
cortical signals can be employed to reproduce, in a robotic
device, the kind of complex arm movements used by primates
to reach objects in space. Here we recorded the simultaneous
activity of large populations of neurons, distributed in the
premotor, primary motor and posterior parietal cortical
areas, as non-human primates performed two distinct motor
tasks. Accurate real-time predictions of one- and
three-dimensional arm movement trajectories were obtained by
applying both linear and nonlinear algorithms to cortical
neuronal ensemble activity recorded from each animal. In
addition, cortically derived signals were successfully used
for real-time control of robotic devices, both locally and
through the Internet. These results suggest that long-term
control of complex prosthetic robot arm movements can be
achieved by simple real-time transformations of neuronal
population signals derived from multiple cortical areas in
primates.},
Key = {fds114958}
}
@article{fds114975,
Author = {EE Fanselow and AP Reid and MA Nicolelis},
Title = {Reduction of pentylenetetrazole-induced seizure activity in
awake rats by seizure-triggered trigeminal nerve
stimulation.},
Journal = {The Journal of neuroscience : the official journal of the
Society for Neuroscience, UNITED STATES},
Volume = {20},
Number = {21},
Pages = {8160-8},
Year = {2000},
Month = {November},
ISSN = {1529-2401},
Keywords = {Animals • Cerebral Cortex • Cortical
Synchronization • Disease Models, Animal •
Electric Stimulation Therapy* • Electrodes, Implanted
• Female • Functional Laterality • Heart Rate
• Membrane Potentials • Pentylenetetrazole •
Rats • Rats, Long-Evans • Reaction Time •
Seizures • Thalamus • Trigeminal Nerve* •
Wakefulness • chemically induced • diagnosis
• physiopathology • therapy*},
Abstract = {Stimulation of the vagus nerve has become an effective
method for desynchronizing the highly coherent neural
activity typically associated with epileptic seizures. This
technique has been used in several animal models of seizures
as well as in humans suffering from epilepsy. However,
application of this technique has been limited to unilateral
stimulation of the vagus nerve, typically delivered
according to a fixed duty cycle, independently of whether
ongoing seizure activity is present. Here, we report that
stimulation of another cranial nerve, the trigeminal nerve,
can also cause cortical and thalamic desynchronization,
resulting in a reduction of seizure activity in awake rats.
Furthermore, we demonstrate that providing this stimulation
only when seizure activity begins results in more effective
and safer seizure reduction per second of stimulation than
with previous methods. Seizure activity induced by
intraperitoneal injection of pentylenetetrazole was recorded
from microwire electrodes in the thalamus and cortex of
awake rats while the infraorbital branch of the trigeminal
nerve was stimulated via a chronically implanted nerve cuff
electrode. Continuous unilateral stimulation of the
trigeminal nerve reduced electrographic seizure activity by
up to 78%, and bilateral trigeminal stimulation was even
more effective. Using a device that automatically detects
seizure activity in real time on the basis of multichannel
field potential signals, we demonstrated that
seizure-triggered stimulation was more effective than the
stimulation protocol involving a fixed duty cycle, in terms
of the percent seizure reduction per second of stimulation.
In contrast to vagus nerve stimulation studies, no
substantial cardiovascular side effects were observed by
unilateral or bilateral stimulation of the trigeminal nerve.
These findings suggest that trigeminal nerve stimulation is
safe in awake rats and should be evaluated as a therapy for
human seizures. Furthermore, the results demonstrate that
seizure-triggered trigeminal nerve stimulation is
technically feasible and could be further developed, in
conjunction with real-time seizure-predicting paradigms, to
prevent seizures and reduce exposure to nerve
stimulation.},
Key = {fds114975}
}
@article{fds114910,
Author = {M Laubach and J Wessberg and MA Nicolelis},
Title = {Cortical ensemble activity increasingly predicts behaviour
outcomes during learning of a motor task.},
Journal = {Nature, ENGLAND},
Volume = {405},
Number = {6786},
Pages = {567-71},
Year = {2000},
Month = {June},
ISSN = {0028-0836},
Keywords = {Analysis of Variance • Animals • Electromyography
• Learning • Male • Motor Cortex • Motor
Skills • Neurons • Rats • Reaction Time
• cytology • physiology •
physiology*},
Abstract = {When an animal learns to make movements in response to
different stimuli, changes in activity in the motor cortex
seem to accompany and underlie this learning. The precise
nature of modifications in cortical motor areas during the
initial stages of motor learning, however, is largely
unknown. Here we address this issue by chronically recording
from neuronal ensembles located in the rat motor cortex,
throughout the period required for rats to learn a
reaction-time task. Motor learning was demonstrated by a
decrease in the variance of the rats' reaction times and an
increase in the time the animals were able to wait for a
trigger stimulus. These behavioural changes were correlated
with a significant increase in our ability to predict the
correct or incorrect outcome of single trials based on three
measures of neuronal ensemble activity: average firing rate,
temporal patterns of firing, and correlated firing. This
increase in prediction indicates that an association between
sensory cues and movement emerged in the motor cortex as the
task was learned. Such modifications in cortical ensemble
activity may be critical for the initial learning of motor
tasks.},
Key = {fds114910}
}
@article{fds114949,
Author = {AA Ghazanfar and CR Stambaugh and MA Nicolelis},
Title = {Encoding of tactile stimulus location by somatosensory
thalamocortical ensembles.},
Journal = {The Journal of neuroscience : the official journal of the
Society for Neuroscience, UNITED STATES},
Volume = {20},
Number = {10},
Pages = {3761-75},
Year = {2000},
Month = {May},
ISSN = {1529-2401},
Keywords = {Action Potentials • Anesthesia • Animals •
Behavior, Animal • Discrimination Learning •
Electrophysiology • Female • Models, Neurological*
• Neurons, Afferent • Rats • Rats, Long-Evans
• Reaction Time • Somatosensory Cortex •
Thalamus • Touch • Vibrissae • cytology*
• innervation • physiology •
physiology*},
Abstract = {The exquisite modular anatomy of the rat somatosensory
system makes it an excellent model to test the potential
coding strategies used to discriminate the location of a
tactile stimulus. Here, we investigated how ensembles of
simultaneously recorded single neurons in layer V of primary
somatosensory (SI) cortex and in the ventral posterior
medial (VPM) nucleus of the thalamus of the anesthetized rat
may encode the location of a single whisker stimulus on a
single trial basis. An artificial neural network based on a
learning vector quantization algorithm, was used to identify
putative coding mechanisms. Our data suggest that these
neural ensembles may rely on a distributed coding scheme to
represent the location of single whisker stimuli. Within
this scheme, the temporal modulation of neural ensemble
firing rate, as well as the temporal interactions between
neurons, contributed significantly to the representation of
stimulus location. The relative contribution of these
temporal codes increased with the number of whiskers that
the ensembles must discriminate among. Our results also
indicated that the SI cortex and the VPM nucleus may
function as a single entity to encode stimulus location.
Overall, our data suggest that the representation of
somatosensory features in the rat trigeminal system may
arise from the interactions of neurons within and between
the SI cortex and VPM nucleus. Furthermore, multiple coding
strategies may be used simultaneously to represent the
location of tactile stimuli.},
Key = {fds114949}
}
@article{fds114970,
Author = {DB Katz and MA Nicolelis and SA Simon},
Title = {Nutrient tasting and signaling mechanisms in the gut. IV.
There is more to taste than meets the tongue.},
Journal = {American journal of physiology. Gastrointestinal and liver
physiology, UNITED STATES},
Volume = {278},
Number = {1},
Pages = {G6-9},
Year = {2000},
Month = {January},
ISSN = {0193-1857},
Keywords = {Animals • Behavior • Central Nervous System •
Epithelium • Humans • Intestines • Nutrition
Physiology* • Signal Transduction* • Taste •
Tongue • physiology • physiology*},
Abstract = {The tongue is the principal organ that provides sensory
information about the quality and quantity of chemicals in
food. Other information about the temperature and texture of
food is also transduced on the tongue, via extragemmal
receptors that form branches of the trigeminal,
glossopharyngeal, and vagal nerves. These systems, together
with information from the gastrointestinal (GI) system,
interact to determine whether or not food is palatable. In
this themes article, emphasis is placed on the integrative
aspects of gustatory processing by showing the convergence
of gustatory information with somatosensory, nociceptive,
and visceral information (from the GI system) on the tongue
and in the brain. Our thesis is that gustation should be
thought of as an integral part of a distributed, interacting
multimodal system in which information from other systems,
including the GI system, can modulate the taste of
food.},
Key = {fds114970}
}
@article{fds114879,
Title = {Ghazanfar AA, Stambaugh CR, Nicolelis MAL (2000) Encoding of
tactile stimulus location by somatosensory thalamocortical
ensembles. J Neurosci 20: 3761-3775.},
Year = {2000},
Key = {fds114879}
}
@article{fds114928,
Title = {Faneslow EE, Reid AP, Nicolelis MAL (2000) Reduction of
pentylenetetrazole-induced seizure activity in awake rats by
seizure-triggered trigeminal nerve stimulation. J Neurosci
20: 8160-8168.},
Year = {2000},
Key = {fds114928}
}
@article{fds114929,
Title = {Ghazanfar AA, Nicolelis MAL (2000) The space-time continuum
in mammalian sensory pathways. In: Time and the Brain (R.
Miller, ed.) Harwood Academic Publishers, Sidney, Australia,
pp. 97-130.},
Year = {2000},
Key = {fds114929}
}
@article{fds114930,
Title = {Katz DB, Nicolelis MAL, Simon SA (2000) There is more to
taste than meets the tongue. Am J Physiol 278:
G6-G9.},
Year = {2000},
Key = {fds114930}
}
@article{fds114931,
Title = {Laubach M, Wessberg J, Nicolelis MAL (2000) Cortical
ensemble activity increasingly predicts behavioral outcomes
during learning of a motor task. Nature 405:
567-571.},
Year = {2000},
Key = {fds114931}
}
@article{fds114932,
Title = {Wessberg J, Stambaugh CR, Kralik JD, Beck PD,
Laubach M, Chapin JK, Kim J, Biggs SJ, Srinivasan MA,
Nicolelis MAL (2000) Real-time prediction of hand trajectory
by ensembles of cortical neurons in primates. Nature 408:
361-365.},
Year = {2000},
Key = {fds114932}
}
@article{fds114943,
Title = {Krupa DJ, Nicolelis MAL (2000) Network level properties of
short-term plasticity in the somatosensory system. Prog
Brain Res 128:161-172.},
Year = {2000},
Key = {fds114943}
}
@article{fds114957,
Author = {DJ Krupa and MA Nicolelis},
Title = {Network level properties of short-term plasticity in the
somatosensory system.},
Journal = {Progress in brain research, NETHERLANDS},
Volume = {128},
Pages = {161-72},
Year = {2000},
ISSN = {0079-6123},
Keywords = {Animals • Denervation • Efferent Pathways •
Feedback • Mechanoreceptors • Nerve Net •
Nerve Regeneration • Neuronal Plasticity •
Neurons, Afferent • Rats • Recovery of Function
• Somatosensory Cortex • Space Perception •
Time Factors • Trigeminal Nuclei • Ventral
Thalamic Nuclei • Vibrissae • adverse effects
• cytology • innervation • physiology •
physiology*},
Key = {fds114957}
}
@article{fds114902,
Author = {JK Chapin and MA Nicolelis},
Title = {Principal component analysis of neuronal ensemble activity
reveals multidimensional somatosensory representations.},
Journal = {Journal of neuroscience methods, NETHERLANDS},
Volume = {94},
Number = {1},
Pages = {121-40},
Year = {1999},
Month = {December},
ISSN = {0165-0270},
Keywords = {Animals • Behavior, Animal • Neurons •
Physical Stimulation • Rats • Rats, Long-Evans
• Sensation • Statistics • Thalamus •
Vibrissae • cytology • physiology •
physiology*},
Abstract = {Principal components analysis (PCA) was used to define the
linearly dependent factors underlying sensory information
processing in the vibrissal sensory area of the ventral
posterior medial (VPM) thalamus in eight awake rats.
Ensembles of up to 23 single neurons were simultaneously
recorded in this area, either during long periods of
spontaneous behavior (including exploratory whisking) or
controlled deflection of single whiskers. PCA rotated the
matrices of correlation between these n neurons into a
series of n uncorrelated principal components (PCs), each
successive PC oriented to explain a maximum of the remaining
variance. The fact that this transformation is
mathematically equivalent to the general Hebb algorithm in
linear neural networks provided a major rationale for
performing it here on data from real neuronal ensembles.
Typically, most information correlated across neurons in the
ensemble was concentrated within the first 3-8 PCs. Each of
these was found to encode distinct, and highly significant
informational factors. These factor encodings were assessed
in two ways, each making use of fact that each PC consisted
of a matrix of weightings, one for each neuron. First, the
neurons were rank ordered according to the locations of the
central whiskers in their receptive fields, allowing their
weightings within different PCs to be viewed as a function
of their position within the whisker representation in the
VPM. Each PC was found to define a distinctly different
topographic mapping of the cutaneous surface. Next, the PCs
were used to weight-sum the neurons' simultaneous activities
to create population vectors (PVs). Each PV consisted of a
single continuous time series which represented the
expression of each PC's 'magnitude' in response to
stimulation of different whiskers, or during behavioral
events such as active tactile whisking. These showed that
each PC functioned as a feature detector capable of
selectively predicting significant sensory or behavioral
events with far greater statistical reliability than could
any single neuron. The encoding characteristics of the first
few PCs were remarkably consistent across all animals and
experimental conditions, including both spontaneous
exploration and direct sensory stimulation: PC1 positively
weighted all neurons, mainly according to their covariance.
Thus it encoded global magnitude of ensemble activity,
caused either by combined sensory inputs or intrinsic
network activity, such as spontaneous oscillations. PC2
encoded spatial position contrast, generally in the
rostrocaudal dimension, across the whole cutaneous surface
represented by the ensemble. PC3 more selectively encoded
contrast in an orthogonal (usually dorsoventral) dimension.
A variable number of higher numbered PCs encoded local
position contrast within one or more smaller regions of the
cutaneous surface. The remaining PCs typically explained
residual 'noise', i.e. the uncorrelated variance that
constituted a major part of each neuron's activity.
Differences in behavioral or sensory experience produced
relatively little in the PC weighting patterns but often
changed the variance they explained (eigenvalues) enough to
alter their ordering. These results argue that PCA provides
a powerful set of tools for selectively measuring neural
ensemble activity within multiple functionally significant
'dimensions' of information processing. As such, it
redefines the 'neuron' as an entity which contributes
portions of its variance to processing not one, but several
tasks.},
Key = {fds114902}
}
@article{fds114971,
Author = {M Laubach and M Shuler and MA Nicolelis},
Title = {Independent component analyses for quantifying neuronal
ensemble interactions.},
Journal = {Journal of neuroscience methods, NETHERLANDS},
Volume = {94},
Number = {1},
Pages = {141-54},
Year = {1999},
Month = {December},
ISSN = {0165-0270},
Keywords = {Action Potentials • Animals • Behavior, Animal
• Cell Communication • Computer Simulation •
Electrophysiology • Male • Models, Neurological*
• Motor Cortex • Neural Networks (Computer) •
Neurons • Rats • Reaction Time • Statistics
• cytology • physiology •
physiology*},
Abstract = {The goal of this study was to compare how multivariate
statistical methods for dimension reduction account for
correlations between simultaneously recorded neurons. Here,
we describe applications of principal component analysis
(PCA) and independent component analysis (ICA) (Cardoso J-F,
Souloumiac A. IEE-Proc F 1993;140:362-70; Hyvarinen A, Oja
E. Neural Comput 1997;9:1483-92; Lee TW, Girolami M,
Sejnowski TJ. Neural Comp 1999;11:417-41) to neuronal
ensemble data. Simulated ensembles of neurons were used to
compare how well the methods above could account for
correlated neuronal firing. The simulations showed that
'population vectors' defined by PCA were broadly distributed
over the neuronal ensembles; thus, PCA was unable to
identify independent groupings of neurons that shared common
sources of input. By contrast, the ICA methods were all able
to identify groupings of neurons that emerged due to
correlated firing. This result suggests that correlated
neuronal firing is reflected in higher-order correlations
between neurons and not simply in the neurons' covariance.
To assess the significance of these methods for real
neuronal ensembles, we analyzed data from populations of
neurons recorded in the motor cortex of rats trained to
perform a reaction-time task. Scores for PCA and ICA were
reconstructed on a bin-by-bin basis for single trials. These
data were then used to train an artificial neural network to
discriminate between single trials with either short or long
reaction-times. Classifications based on scores from the
ICA-based methods were significantly better than those based
on PCA. For example, scores for components defined with an
ICA-based method, extended ICA (Lee et al., 1999),
classified more trials correctly (80.58+/-1.25%) than PCA
(73.14+/-0.84%) for an ensemble of 26 neurons recorded in
the motor cortex (ANOVA: P < 0.005). This result suggests
that behaviorally relevant information is represented in
correlated neuronal firing and can be best detected when
higher-order correlations between neurons are taken into
account.},
Key = {fds114971}
}
@article{fds114897,
Author = {EE Fanselow and MA Nicolelis},
Title = {Behavioral modulation of tactile responses in the rat
somatosensory system.},
Journal = {The Journal of neuroscience : the official journal of the
Society for Neuroscience, UNITED STATES},
Volume = {19},
Number = {17},
Pages = {7603-16},
Year = {1999},
Month = {September},
ISSN = {1529-2401},
Keywords = {Animals • Brain Mapping • Electric Stimulation
• Female • Motor Activity • Movement •
Neurons • Ophthalmic Nerve • Physical Stimulation
• Rats • Rats, Long-Evans • Reaction Time
• Somatosensory Cortex • Thalamic Nuclei •
Touch • Vibrissae • innervation • physiology
• physiology*},
Abstract = {We investigated the influence of four different behavioral
states on tactile responses recorded simultaneously via
arrays of microwires chronically implanted in the vibrissal
representations of the rat ventral posterior medial nucleus
(VPM) of the thalamus and the primary somatosensory cortex
(SI). Brief (100 microsecond) electrical stimuli delivered
via a cuff electrode to the infraorbital nerve yielded
robust sensory responses in VPM and SI during states of
quiet immobility. However, significant reductions in tactile
response magnitude and latency were observed in VPM and SI
during large-amplitude, exploratory movements of the
whiskers (at approximately 4-6 Hz). During small-amplitude,
7-12 Hz whisker-twitching movements, a significant reduction
in SI response magnitude and an increase in VPM and SI
response latencies were observed as well. When pairs of
stimuli with interstimulus intervals <100 msec were
delivered during quiet immobility, the response to the
second stimulus in the pair was reduced and occurred at a
longer latency compared with the response to the first
stimulus. In contrast, during large-amplitude whisker
movements and general motor activity, paired stimuli yielded
similar sensory responses at interstimulus intervals >25
msec. These response patterns were correlated with the
amount and duration of postexcitatory firing suppression
observed in VPM and SI during each of these behaviors. On
the basis of these results, we propose that sensory
responses are dynamically modulated during active tactile
exploration to optimize detection of different types of
stimuli. During quiet immobility, the somatosensory system
seems to be optimally tuned to detect the presence of single
stimuli. In contrast, during whisker movements and other
exploratory behaviors, the system is primed to detect the
occurrence of rapid sequences of tactile stimuli, which are
likely to be generated by multiple whisker contacts with
objects during exploratory activity.},
Key = {fds114897}
}
@article{fds114905,
Author = {DB Katz and SA Simon and A Moody and MA Nicolelis},
Title = {Simultaneous reorganization in thalamocortical ensembles
evolves over several hours after perioral capsaicin
injections.},
Journal = {Journal of neurophysiology, UNITED STATES},
Volume = {82},
Number = {2},
Pages = {963-77},
Year = {1999},
Month = {August},
ISSN = {0022-3077},
Keywords = {Analysis of Variance • Animals • Capsaicin •
Female • Injections • Injections, Subcutaneous
• Multivariate Analysis • Neurons • Rats
• Rats, Long-Evans • Somatosensory Cortex •
Thalamus • Vibrissae • drug effects* •
innervation • pharmacology*},
Abstract = {Reorganization of the somatosensory system was quantified by
simultaneously recording from single-unit neural ensembles
in the whisker regions of the ventral posterior medial (VPM)
nucleus of the thalamus and the primary somatosensory (SI)
cortex in anesthetized rats before, during, and after
injecting capsaicin under the skin of the lip. Capsaicin, a
compound that excites and then inactivates a subset of
peripheral C and Adelta fibers, triggered increases in
spontaneous firing of thalamocortical neurons (10-15 min
after injection), as well as rapid reorganization of the
whisker representations in both the VPM and SI. During the
first hour after capsaicin injection, 57% of the 139
recorded neurons either gained or lost at least one whisker
response in their receptive fields (RFs). Capsaicin-related
changes continued to emerge for >/=6 h after the injection:
Fifty percent of the single-neuron RFs changed between 1-2
and 5-6 h after capsaicin injection. Most (79%) of these
late changes represented neural responses that had remained
unchanged in the first postcapsaicin mapping; just under 20%
of these late changes appeared in neurons that had
previously shown no plasticity of response. The majority of
the changes (55% immediately after injection, 66% 6 h later)
involved "unmasking" of new tactile responses. RF change
rates were comparable in SI and VPM (57-49%). Population
analysis indicated that the reorganization was associated
with a lessening of the "spatial coupling" between cortical
neurons-a significant reduction in firing covariance that
could be related to distances between neurons. This general
loss of spatial coupling, in conjunction with increases in
spontaneous firing, may create a situation that is favorable
for the induction of synaptic plasticity. Our results
indicate that the selective inactivation of a peripheral
nociceptor subpopulation can induce rapid and long-evolving
(>/=6 h) shifts in the balance of inhibition and excitation
in the somatosensory system. The time course of these
processes suggest that thalamic and cortical plasticity is
not a linear reflection of spinal and brainstem changes that
occur following the application of capsaicin.},
Key = {fds114905}
}
@article{fds114946,
Author = {DJ Krupa and AA Ghazanfar and MA Nicolelis},
Title = {Immediate thalamic sensory plasticity depends on
corticothalamic feedback.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America, UNITED STATES},
Volume = {96},
Number = {14},
Pages = {8200-5},
Year = {1999},
Month = {July},
ISSN = {0027-8424},
Keywords = {Animals • Brain Mapping* • Electric Stimulation
• Female • Infusions, Parenteral • Lidocaine
• Muscimol • Nerve Fibers • Neural Pathways
• Neuronal Plasticity* • Neurons • Rats
• Rats, Long-Evans • Somatosensory Cortex •
Thalamus • Time Factors • Trigeminal Nerve •
Vibrissae • administration & dosage • drug effects
• innervation • pharmacology • physiology
• physiology*},
Abstract = {Multiple neuron ensemble recordings were obtained
simultaneously from both the primary somatosensory (SI)
cortex and the ventroposterior medial thalamus (VPM) before
and during the combined administration of reversible
inactivation of the SI cortex and a reversible subcutaneous
block of peripheral trigeminal nerve fibers. This procedure
was performed to quantify the contribution of descending
corticofugal projections on (i) the normal organization of
thalamic somatosensory receptive fields and (ii) the
thalamic somatosensory plastic reorganization that
immediately follows a peripheral deafferentation. Reversible
inactivation of SI cortex resulted in immediate changes in
receptive field properties throughout the VPM. Cortical
inactivation also significantly reduced but did not
completely eliminate the occurrence of VPM receptive field
reorganization resulting from the reversible peripheral
deafferentation. This result suggests that the thalamic
plasticity that is seen immediately after a peripheral
deafferentation is dependent upon both descending
corticofugal projections and ascending trigeminothalamic
projections.},
Key = {fds114946}
}
@article{fds114976,
Author = {JK Chapin and KA Moxon and RS Markowitz and MA Nicolelis},
Title = {Real-time control of a robot arm using simultaneously
recorded neurons in the motor cortex.},
Journal = {Nature neuroscience, UNITED STATES},
Volume = {2},
Number = {7},
Pages = {664-70},
Year = {1999},
Month = {July},
ISSN = {1097-6256},
Keywords = {Animals • Arm* • Cerebral Cortex • Computer
Systems • Forelimb • Motor Activity* • Motor
Cortex • Movement • Multivariate Analysis •
Nerve Net • Neurons • Rats • Rats, Long-Evans
• Robotics* • Thalamus • innervation •
physiology • physiology*},
Abstract = {To determine whether simultaneously recorded motor cortex
neurons can be used for real-time device control, rats were
trained to position a robot arm to obtain water by pressing
a lever. Mathematical transformations, including neural
networks, converted multineuron signals into 'neuronal
population functions' that accurately predicted lever
trajectory. Next, these functions were electronically
converted into real-time signals for robot arm control.
After switching to this 'neurorobotic' mode, 4 of 6 animals
(those with > 25 task-related neurons) routinely used these
brain-derived signals to position the robot arm and obtain
water. With continued training in neurorobotic mode, the
animals' lever movement diminished or stopped. These results
suggest a possible means for movement restoration in
paralysis patients.},
Key = {fds114976}
}
@article{fds114952,
Author = {AA Ghazanfar and MA Nicolelis},
Title = {Spatiotemporal properties of layer V neurons of the rat
primary somatosensory cortex.},
Journal = {Cerebral cortex (New York, N.Y. : 1991), UNITED
STATES},
Volume = {9},
Number = {4},
Pages = {348-61},
Year = {1999},
Month = {June},
ISSN = {1047-3211},
Keywords = {Animals • Electrodes, Implanted • Excitatory
Postsynaptic Potentials • Female • Membrane
Potentials • Microelectrodes • Neurons •
Physical Stimulation • Rats • Rats, Long-Evans
• Somatosensory Cortex • Space Perception •
Time Perception • Vibrissae • anatomy & histology
• cytology • physiology •
physiology*},
Abstract = {Animals in their natural environments actively process
spatiotemporally complex sensory signals in order to guide
adaptive behavior. It therefore seems likely that the
properties of both single neurons and neural ensembles
should reflect the dynamic nature of such interactions.
During exploratory behaviors, rats move their whiskers to
actively discriminate between different tactile features. We
investigated whether this dynamic sensory processing was
reflected in the spatial and temporal properties of neurons
in layer V of the 'whisker area' in the rat primary
somatosensory cortex. We found that the majority of layer V
neurons had large (8.5+/-4.9 whiskers) spatiotemporal
receptive fields (i.e. individual cells responded best to
different whiskers as a function of post-stimulus time), and
that the excitatory responses of surround whiskers formed a
spatial gradient of excitation that seemed to reflect the
greater use of the ventral and caudal whiskers during
natural behaviors. Analyses of ensembles of layer V neurons
revealed that single-whisker stimuli activated a portion of
layer V that extends well beyond a single cortical column
(average of 5.6 barrel cortical columns). Based on these
results, we conclude that the rat primary somatosensory
cortex does not appear to operate as a static decoder of
tactile information. On the contrary, our data suggest that
tactile processing in rats is likely to involve the on-going
interactions between populations of broadly tuned neurons in
the thalamocortical pathway.},
Key = {fds114952}
}
@article{fds114877,
Title = {Fanselow E, Nicolelis MAL (1999) Behavioral modulation of
tactile responses in the rat somatosensory system. J
Neurosci 19: 7603-7616.},
Year = {1999},
Key = {fds114877}
}
@article{fds114878,
Title = {Laubach M, Shuler M, Nicolelis MAL (1999) Independent
component analyses for quantifying neuronal ensemble
interactions. J Neurosci Meth 94: 141-154.},
Year = {1999},
Key = {fds114878}
}
@article{fds114915,
Title = {Krupa DJ, Ghazanfar AA, Nicolelis MAL (1999) Immediate
thalamic sensory plasticity depends on corticothalamic
feedback. Proc Natl Acad Sci USA 96: 8200-8205.},
Year = {1999},
Key = {fds114915}
}
@article{fds114924,
Title = {Chapin JK, Nicolelis MAL (1999) Principal component analysis
of neuronal ensemble activity reveals multidimensional
sensory representations. J Neurosci Meth 94:
121-140.},
Year = {1999},
Key = {fds114924}
}
@article{fds114925,
Title = {Chapin JK, Markowitz RS, Moxon KA, Nicolelis MAL (1999)
Real-time control of a robot arm using simultaneously
recorded neurons in the motor cortex. Nature Neurosci 2:
664-670.},
Year = {1999},
Key = {fds114925}
}
@article{fds114926,
Title = {Ghazanfar AA, Nicolelis MAL (1999) Spatiotemporal properties
of layer V neurons in the rat primary somatosensory cortex.
Cerebral Cortex 9: 348-361.},
Year = {1999},
Key = {fds114926}
}
@article{fds114927,
Title = {Katz DB, Simon SA, Nicolelis MAL (1999) Simultaneous
reorganization in thalamcortical ensembles evolves over
several hours after perioral capsaicin injections. J
Neurophysiol 82: 963-977.},
Year = {1999},
Key = {fds114927}
}
@article{fds114977,
Author = {MA Nicolelis and AA Ghazanfar and CR Stambaugh and LM Oliveira and M
Laubach, JK Chapin and RJ Nelson and JH Kaas},
Title = {Simultaneous encoding of tactile information by three
primate cortical areas.},
Journal = {Nature neuroscience, UNITED STATES},
Volume = {1},
Number = {7},
Pages = {621-30},
Year = {1998},
Month = {November},
ISSN = {1097-6256},
Keywords = {Action Potentials • Animals • Aotidae •
Electrophysiology • Hand • Neurons • Physical
Stimulation • Reaction Time • Somatosensory Cortex
• Touch • cytology • physiology •
physiology*},
Abstract = {We used simultaneous multi-site neural ensemble recordings
to investigate the representation of tactile information in
three areas of the primate somatosensory cortex (areas 3b,
SII and 2). Small neural ensembles (30-40 neurons) of
broadly tuned somatosensory neurons were able to identify
correctly the location of a single tactile stimulus on a
single trial, almost simultaneously. Furthermore, each of
these cortical areas could use different combinations of
encoding strategies, such as mean firing rate (areas 3b and
2) or temporal patterns of ensemble firing (area SII), to
represent the location of a tactile stimulus. Based on these
results, we propose that ensembles of broadly tuned neurons,
located in three distinct areas of the primate somatosensory
cortex, obtain information about the location of a tactile
stimulus almost concurrently.},
Key = {fds114977}
}
@article{fds114870,
Title = {Nicolelis MAL, Ghazanfar AA, Oliveira LMO, Chapin JK, Nelson
R, Kaas JH (1998) Simultaneous encoding of tactile
information by three primate cortical areas. Nature Neurosci
1: 621-630.},
Year = {1998},
Key = {fds114870}
}
@article{fds114944,
Author = {RC Lin and MA Nicolelis and JK Chapin},
Title = {Topographic and laminar organizations of the incertocortical
pathway in rats.},
Journal = {Neuroscience, UNITED STATES},
Volume = {81},
Number = {3},
Pages = {641-51},
Year = {1997},
Month = {December},
ISSN = {0306-4522},
Keywords = {Anatomy, Artistic • Animals • Brain Mapping •
Cerebral Cortex • Fluorescent Dyes • Medical
Illustration • Neural Pathways • Rats • Rats,
Inbred Strains • Thalamic Nuclei • anatomy &
histology • physiology • physiology*},
Abstract = {The topographic and laminar organizations of the projection
system from the zona incerta to the neocortex were studied
by using both retrograde and anterograde methods in the rat.
Injections of retrograde fluorescent tracers into different
cortical areas revealed that the incertocortical projection
neurons have a rough topographic organization with respect
to their cortical targets. Furthermore, the incertocortical
projecting neurons were found mainly in the dorsal and
rostral subdivisions of the zona incerta, and none were
found in the ventral subdivision. In cases which included
three different fluorescent tracers injected into the
frontal, the parietal and the occipital cortices,
retrogradely single-labelled cells were found intermingled
within the dorsal zona incerta. Very few double-labelled
cells were noted, and triple-labelled cells were absent.
Injections of anterograde tracers into the dorsal zona
incerta demonstrate that labelled fibres traverse the
striatum and terminate most densely in the outer half of
layer I of the neocortex. The density of incertocortical
terminals was greatest in the somatosensory cortex, while
the innervation of visual cortical areas was sparse. Very
fine and sparse bouton-like swellings of labelled
incertocortical fibres were found running parallel along the
pial surface. Since it has recently been shown that the
incertocortical projections derive from GABAergic neurons,
the present results suggest that the diffuse and roughly
topographic projection from the zona incerta to the cerebral
cortex may play an inhibitory role in widespread areas of
cerebral cortex. This inhibitory action may preferentially
target the distal dendrites of cortical neurons, since the
majority of incertocortical terminals were found in the
outer part of layer I of the neocortex.},
Key = {fds114944}
}
@article{fds114907,
Author = {MA Nicolelis and RC Lin and JK Chapin},
Title = {Neonatal whisker removal reduces the discrimination of
tactile stimuli by thalamic ensembles in adult
rats.},
Journal = {Journal of neurophysiology, UNITED STATES},
Volume = {78},
Number = {3},
Pages = {1691-706},
Year = {1997},
Month = {September},
ISSN = {0022-3077},
Keywords = {Animals • Animals, Newborn • Discrimination
(Psychology) • Neuronal Plasticity • Neurons,
Afferent • Rats • Thalamus • Touch •
Vibrissae • growth & development* • physiology
• physiology*},
Abstract = {Simultaneous recordings of up to 48 single neurons per
animal were used to characterize the long-term functional
effects of sensory plastic modifications in the ventral
posterior medial nucleus (VPM) of the thalamus following
unilateral removal of facial whiskers in newborn rats. One
year after this neonatal whisker deprivation, neurons in the
contralateral VPM responded to cutaneous stimulation of the
face at much longer minimal latencies (15.2 +/- 8.2 ms, mean
+/- SD) than did normal cells (8.8 +/- 5.3 ms) in the same
subregion of the VPM. In 69% of these neurons, the initial
sensory responses to stimulus offset were followed for up to
700 ms by reverberant trains of bursting discharge,
alternating in 100-ms cycles with inhibition. Receptive
fields in the deafferented VPM were also atypical in that
they extended over the entire face, shoulder, forepaw,
hindpaw, and even ipsilateral whiskers. Discriminant
analysis (DA) was then used to statistically evaluate how
this abnormal receptive field organization might affect the
ability of thalamocortical neuronal populations to
"discriminate" somatosensory stimulus location. To
standardize this analysis, three stimulus targets ("groups")
were chosen in all animals such that they triangulated the
central region of the "receptive field" of the recorded
multineuronal ensemble. In the normal animals these stimulus
targets were whiskers or perioral hairs; in the deprived
animals the targets typically included hairy skin of the
body as well as face. The measured variables consisted of
each neuron's spiking response to each stimulus
differentiated into three poststimulus response epochs
(0-15, 15-30, and 30-45 ms). DA quantified the statistical
contribution of each of these variables to its overall
discrimination between the three stimulus sites. In the
normal animals, the stimulus locations were correctly
classified in 88.2 +/- 3.7% of trials on the basis of the
spatiotemporal patterns of ensemble activity derived from up
to 18 single neurons. In the deprived animals, the stimulus
locations were much less consistently discriminated (reduced
to 73.5 +/- 12.6%; difference from controls significant at P
< 0.01) despite the fact that much more widely spaced
stimulus targets were used and even when up to 20 neurons
were included in the ensemble. Overall, these results
suggest that neonatal damage to peripheral sense organs may
produce marked changes in the physiology of individual
neurons in the somatosensory thalamus. Moreover, the present
demonstration that these changes can profoundly alter
sensory discrimination at the level of neural populations in
the thalamus provides important evidence that the well-known
perceptual effects of chronic peripheral deprivation may be
partially attributable to plastic reorganization at
subcortical levels.},
Key = {fds114907}
}
@article{fds114893,
Author = {BM Faggin and KT Nguyen and MA Nicolelis},
Title = {Immediate and simultaneous sensory reorganization at
cortical and subcortical levels of the somatosensory
system.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America, UNITED STATES},
Volume = {94},
Number = {17},
Pages = {9428-33},
Year = {1997},
Month = {August},
ISSN = {0027-8424},
Keywords = {Animals • Neuronal Plasticity* • Psychomotor
Performance • Rats • Somatosensory Cortex •
physiology*},
Abstract = {The occurrence of cortical plasticity during adulthood has
been demonstrated using many experimental paradigms. Whether
this phenomenon is generated exclusively by changes in
intrinsic cortical circuitry, or whether it involves
concomitant cortical and subcortical reorganization, remains
controversial. Here, we addressed this issue by
simultaneously recording the extracellular activity of up to
135 neurons in the primary somatosensory cortex, ventral
posterior medial nucleus of the thalamus, and trigeminal
brainstem complex of adult rats, before and after a
reversible sensory deactivation was produced by subcutaneous
injections of lidocaine. Following the onset of the
deactivation, immediate and simultaneous sensory
reorganization was observed at all levels of the
somatosensory system. No statistical difference was observed
when the overall spatial extent of the cortical (9.1 +/- 1.2
whiskers, mean +/- SE) and the thalamic (6.1 +/- 1.6
whiskers) reorganization was compared. Likewise, no
significant difference was found in the percentage of
cortical (71.1 +/- 5.2%) and thalamic (66. 4 +/- 10.7%)
neurons exhibiting unmasked sensory responses. Although
unmasked cortical responses occurred at significantly higher
latencies (19.6 +/- 0.3 ms, mean +/- SE) than thalamic
responses (13. 1 +/- 0.6 ms), variations in neuronal latency
induced by the sensory deafferentation occurred as often in
the thalamus as in the cortex. These data clearly
demonstrate that peripheral sensory deafferentation triggers
a system-wide reorganization, and strongly suggest that the
spatiotemporal attributes of cortical plasticity are
paralleled by subcortical reorganization.},
Key = {fds114893}
}
@article{fds114909,
Author = {MA Nicolelis and EE Fanselow and AA Ghazanfar},
Title = {Hebb's dream: the resurgence of cell assemblies.},
Journal = {Neuron, UNITED STATES},
Volume = {19},
Number = {2},
Pages = {219-21},
Year = {1997},
Month = {August},
ISSN = {0896-6273},
Keywords = {Animals • Hippocampus • Neuronal Plasticity •
Neurons, Afferent • Presynaptic Terminals •
physiology*},
Key = {fds114909}
}
@article{fds114973,
Author = {AA Ghazanfar and MA Nicolelis},
Title = {Nonlinear processing of tactile information in the
thalamocortical loop.},
Journal = {Journal of neurophysiology, UNITED STATES},
Volume = {78},
Number = {1},
Pages = {506-10},
Year = {1997},
Month = {July},
ISSN = {0022-3077},
Keywords = {Animals • Cerebral Cortex • Mental Processes
• Neurons • Nonlinear Dynamics • Rats •
Thalamus • Touch • Vibrissae • cytology
• physiology*},
Abstract = {Rats explore tangible objects in a manner such that, at any
given moment in time, multiple facial whiskers
simultaneously contact the surface of the object. Although
both thalamic and cortical neurons responsible for
processing such tactile information have large, multiwhisker
receptive fields, it remains unclear what kinds of
computations can be carried out by these neuronal
populations when behaviorally relevant multiwhisker stimuli
are used. By simultaneously recording the activity of up to
78 cortical and thalamic neurons per animal, we observed
that the magnitude of sensory responses and the spatial
spread of ensemble activity increased in a nonlinear fashion
according to the extent and spatial orientation of the
multiwhisker stimuli. Supralinear responses were seen more
frequently with vertically than with horizontally oriented
stimuli. These data suggest that thalamocortical
interactions in the rat somatosensory system can generate
complex spatial transformations of multiwhisker stimuli that
go beyond the classic inhibitory interactions previously
observed.},
Key = {fds114973}
}
@article{fds114974,
Author = {MA Nicolelis and AA Ghazanfar and BM Faggin and S Votaw and LM
Oliveira},
Title = {Reconstructing the engram: simultaneous, multisite, many
single neuron recordings.},
Journal = {Neuron, UNITED STATES},
Volume = {18},
Number = {4},
Pages = {529-37},
Year = {1997},
Month = {April},
ISSN = {0896-6273},
Keywords = {Animals • Brain • Cell Communication •
Electrophysiology • Equipment Design •
Extracellular Space • Neurons • Rats •
cytology • instrumentation • methods* •
physiology • physiology*},
Abstract = {Little is known about the physiological principles that
govern large-scale neuronal interactions in the mammalian
brain. Here, we describe an electrophysiological paradigm
capable of simultaneously recording the extracellular
activity of large populations of single neurons, distributed
across multiple cortical and subcortical structures in
behaving and anesthetized animals. Up to 100 neurons were
simultaneously recorded after 48 microwires were implanted
in the brain stem, thalamus, and somatosensory cortex of
rats. Overall, 86% of the implanted microwires yielded
single neurons, and an average of 2.3 neurons were
discriminated per microwire. Our population recordings
remained stable for weeks, demonstrating that this method
can be employed to investigate the dynamic and distributed
neuronal ensemble interactions that underlie processes such
as sensory perception, motor control, and sensorimotor
learning in freely behaving animals.},
Key = {fds114974}
}
@article{fds114874,
Title = {Ghazanfar AA, Nicolelis MAL (1997) Non-linear processing
of tactile information in the thalamocortical loop. J
Neurophysiol 78:506-510.},
Year = {1997},
Key = {fds114874}
}
@article{fds114875,
Title = {Nicolelis MAL, Fanselow E, Ghazanfar AA (1997) Hebb's dream:
The resurgence of cell assemblies. Neuron
19(2):219-221.},
Year = {1997},
Key = {fds114875}
}
@article{fds114876,
Title = {Nicolelis MAL, Lin RCS, Chapin JK (1997) Neonatal whisker
removal reduces the discrimination of tactile stimuli by
thalamic ensembles in adult rats. J Neurophysiol 78:
1691-1706.},
Year = {1997},
Key = {fds114876}
}
@article{fds114920,
Title = {Faggin B, Ngyuen KT, Nicolelis MAL (1997) Immediate and
simultaneous plastic reorganization at multiple levels of
the somatosensory system. Proc Natl Acad Soc USA
94:9428-9433.},
Year = {1997},
Key = {fds114920}
}
@article{fds114921,
Title = {Nicolelis MAL (1997) Dynamic and distributed somatosensory
organization as the substrate for cortical and subcortical
plasticity. Seminars in Neurosciences 9:24-33.},
Year = {1997},
Key = {fds114921}
}
@article{fds114922,
Title = {Nicolelis MAL, Ghazanfar AA, Faggin B, Votaw S, Oliveira LMO
(1997) Reconstructing the engram: simultaneous, multiple
site, many single neuron recordings. Neuron
18:529-537},
Year = {1997},
Key = {fds114922}
}
@article{fds114923,
Title = {Lin CS, Nicolelis MAL, Chapin JK (1997) Topography and
laminar organization of the incertocortical pathway in rats.
Neuroscience 81: 641-651.},
Year = {1997},
Key = {fds114923}
}
@article{fds114954,
Author = {MA Nicolelis and LM De Oliveira and RC Lin and JK
Chapin},
Title = {Active tactile exploration influences the functional
maturation of the somatosensory system.},
Journal = {Journal of neurophysiology, UNITED STATES},
Volume = {75},
Number = {5},
Pages = {2192-6},
Year = {1996},
Month = {May},
ISSN = {0022-3077},
Keywords = {Animals • Animals, Newborn • Denervation •
Exploratory Behavior • Facial Nerve • Neurons,
Afferent • Rats • Somatosensory Cortex •
Thalamus • Touch • Vibrissae • growth &
development • growth & development* • physiology
• physiology*},
Abstract = {1. The hypothesis that active exploration of objects is
required for the functional maturation of neuronal circuits
subserving tactile perception was tested by subjecting 8- to
11-day old rats to a complete unilateral section of the
facial nerve. This procedure selectively abolished whisker
protraction movements without affecting the sensory
innervation of the facial vibrissae, the tactile organs used
by rats to discriminate object texture and shape. 2. Six to
14 mo after the facial nerve section, simultaneous
recordings of neuronal ensembles located in the ventral
posterior medial nucleus (VPM) of the thalamus revealed a
marked reduction in receptive field (RF) size (in terms of
number of whiskers), and the formation of abnormal RF
surrounds, spanning the face and contiguous body regions. In
addition, the directional organization of VPM RFs,
represented by caudal to rostral shifts in RF centers over
30 ms following whisker stimulation, was greatly reduced in
these animals. 3. These results suggest that neonatal active
tactile exploration is required to establish normal
spatiotemporal patterning of neuronal RFs within the
somatosensory system, and consequently, to develop normal
tactile perception.},
Key = {fds114954}
}
@article{fds114903,
Author = {MA Nicolelis},
Title = {Beyond maps: a dynamic view of the somatosensory
system.},
Journal = {Brazilian journal of medical and biological research =
Revista brasileira de pesquisas médicas e biológicas /
Sociedade Brasileira de Biofísica ... [et al.],
BRAZIL},
Volume = {29},
Number = {4},
Pages = {401-12},
Year = {1996},
Month = {April},
ISSN = {0100-879X},
Keywords = {Animals • Nerve Net • Rats • Somatosensory
Cortex • physiology*},
Abstract = {Current theories on how tactile information is processed by
the mammalian somatosensory system are based primarily on
data obtained in studies in which the physiological
properties of single neurons were characterized, one at a
time, in behaving or anesthetized animals. Yet, the central
nervous system relies on the concurrent activation of large
populations of neurons to process the variety of sensory
stimuli that contribute to normal tactile perception. The
recent introduction of electrophysiological methods for
chronic and simultaneous recordings of the extracellular
activity of large numbers of single neurons per animal has
allowed us to investigate, for the first time, how
populations of neurons, located at multiple processing
stages of the somatosensory system, interact following
passive and active tactile stimulation. The rat trigeminal
somatosensory system was used as a model for this
investigation. Our results revealed the existence of highly
dynamic and distributed representations of tactile
information, not only in the somatosensory cortex, but also
in the thalamus and even in the brainstem. In these
structures, we identified broadly tuned neurons with
multiwhisker receptive fields (RFs). In the thalamus, a
large percentage of neurons exhibited shifts in the spatial
domain of their RFs as a function of post-stimulus time.
During these shifts, the center of the neuron's RF moved
across the whisker pad from caudal to rostral whiskers, but
not in the opposite direction, suggesting that these
spatiotemporal RFs may encode directional information.
Further studies revealed that somatosensory representations
were maintained by dynamic interactions between multiple
convergent afferents, since they could be altered in a
matter of seconds by reversible sensory deprivations.
Overall, these results suggest that the rat somatosensory
system relies on both spatial and temporal interactions
between populations of cortical and subcortical neurons to
process multiple attributes of tactile stimuli.},
Key = {fds114903}
}
@article{fds114953,
Author = {RC Lin and MA Nicolelis and HL Zhou and JK Chapin},
Title = {Calbindin-containing non-specific thalamocortical projecting
neurons in the rat.},
Journal = {Brain research, NETHERLANDS},
Volume = {711},
Number = {1-2},
Pages = {50-5},
Year = {1996},
Month = {March},
ISSN = {0006-8993},
Keywords = {Animals • Calcium-Binding Protein, Vitamin D-Dependent
• Cerebral Cortex • Female •
Immunohistochemistry • Male • Neural Pathways
• Rats • Thalamus • anatomy & histology*
• chemistry*},
Abstract = {Immunoreactivity for calcium binding proteins was used to
demonstrate the neurochemical profiles of non-specific
thalamocortical neurons located in the ventromedial nucleus,
the centrolateral nucleus, and the nucleus reuniens that
project to the somatosensory cortex in the adult rat.
Cortical injections of fluorescent tracers combined with
immunohistochemistry for calcium binding proteins revealed
that retrogradely labeled neurons in these three thalamic
nuclei are immunoreactive for calbindin. The present results
suggest the presence of a chemically distinct non-specific
thalamocortical system which terminates in the
neocortex.},
Key = {fds114953}
}
@article{fds114872,
Title = {Chapin JK, Nicolelis MAL (1996) Neural network mechanisms of
oscillatory brain states: characterization using
simultaneous multi-single neuron recordings., In: Continuous
waveform analysis, R.M. Basheiss and D.J. Vicent (eds).
Electroenceph Clin Neurophysiol, suppl 45, pp
113-122.},
Year = {1996},
Key = {fds114872}
}
@article{fds114873,
Title = {Lin RCS, Nicolelis MAL, Zhou HL, Chapin JK (1996)
Calbindin-containing, non-specific thalamocortical
projecting neurons in the rat. Brain Research 711:
50-55.},
Year = {1996},
Key = {fds114873}
}
@article{fds114918,
Title = {Nicolelis MAL, Oliveira LMO, Lin RCS, Chapin JK (1996)
Active tactile exploration influences the functional
maturation of the somatosensory system. J Neurophysiol 17:
2192-2196.},
Year = {1996},
Key = {fds114918}
}
@article{fds114919,
Title = {Nicolelis MAL (1996) Beyond maps: A dynamic view of the
somatosensory system. Braz J Med Biol Res 29:
401-412.},
Year = {1996},
Key = {fds114919}
}
@article{fds114960,
Author = {JK Chapin and MA Nicolelis},
Title = {Neural network mechanisms of oscillatory brain states:
characterization using simultaneous multi-single neuron
recordings.},
Journal = {Electroencephalography and clinical neurophysiology.
Supplement, IRELAND},
Volume = {45},
Pages = {113-22},
Year = {1996},
ISSN = {0424-8155},
Keywords = {Animals • Brain • Electroencephalography •
Face • Nerve Net • Neurons • Oscillometry
• Periodicity • Rats • Somatosensory Cortex
• Thalamus • Vibrissae • cytology •
physiology • physiology*},
Key = {fds114960}
}
@article{fds114964,
Author = {MA Nicolelis and LA Baccala and RC Lin and JK Chapin},
Title = {Sensorimotor encoding by synchronous neural ensemble
activity at multiple levels of the somatosensory
system.},
Journal = {Science (New York, N.Y.), UNITED STATES},
Volume = {268},
Number = {5215},
Pages = {1353-8},
Year = {1995},
Month = {June},
ISSN = {0036-8075},
Keywords = {Animals • Brain • Electromyography •
Electrophysiology • Motor Cortex • Nerve Net
• Neural Pathways • Neurons, Afferent • Rats
• Somatosensory Cortex • Thalamic Nuclei •
Touch • Trigeminal Ganglion • Trigeminal Nuclei
• Vibrissae • innervation* • physiology
• physiology*},
Abstract = {Neural ensemble processing of sensorimotor information
during behavior was investigated by simultaneously recording
up to 48 single neurons at multiple relays of the rat
trigeminal somatosensory system. Cortical, thalamic, and
brainstem neurons exhibited widespread 7- to 12-hertz
synchronous oscillations, which began during attentive
immobility and reliably predicted the imminent onset of
rhythmic whisker twitching. Each oscillatory cycle began as
a traveling wave of neural activity in the cortex that then
spread to the thalamus. Just before the onset of rhythmic
whisker twitching, the oscillations spread to the spinal
trigeminal brainstem complex. Thereafter, the oscillations
at all levels were synchronous with whisker protraction.
Neural structures manifesting these rhythms also exhibited
distributed spatiotemporal patterns of neuronal ensemble
activity in response to tactile stimulation. Thus,
multilevel synchronous activity in this system may encode
not only sensory information but also the onset and temporal
domain of tactile exploratory movements.},
Key = {fds114964}
}
@article{fds114894,
Author = {MA Nicolelis and JK Chapin and RC Lin},
Title = {Development of direct GABAergic projections from the zona
incerta to the somatosensory cortex of the
rat.},
Journal = {Neuroscience, ENGLAND},
Volume = {65},
Number = {2},
Pages = {609-31},
Year = {1995},
Month = {March},
ISSN = {0306-4522},
Keywords = {Animals • Calcium-Binding Protein, Vitamin D-Dependent
• Electron Transport Complex IV • Fluorescent Dyes
• Glutamate Decarboxylase • Immunohistochemistry
• Neural Pathways • Parvalbumins • Rats
• Somatosensory Cortex • Stilbamidines* •
Thalamic Nuclei • Thalamus • anatomy & histology
• cytology • gamma-Aminobutyric Acid • growth
& development • growth & development* • metabolism
• physiology*},
Abstract = {The postnatal development of direct thalamocortical
projections from the zona incerta of the ventral thalamus to
the whisker representation area of the rat primary
somatosensory cortex was investigated. Cytoarchitectonic
analysis based on Nissl staining, cytochrome oxidase
histochemistry and immunohistochemistry for glutamic acid
decarboxylase, GABA, parvalbumin and calbindin D28K revealed
that the zona incerta can be clearly distinguished from
surrounding diencephalic structures from the day of birth.
Moreover, four distinct anatomical subdivisions of this
nucleus were identified: the rostral, dorsal, ventral and
caudal. Of these, the ventral subdivision is by far the most
conspicuous, containing the highest density of neurons, and
the highest levels of cytochrome oxidase, glutamate
decarboxylase, GABA, parvalbumin and calbindin D28K. In
contrast, the dorsal, rostral and caudal subdivisions
contain fewer cells, lower levels of glutamic acid
decarboxylase and GABA and very few parvalbumin-positive and
calbindin-positive neurons. Small injections of rhodamine
coated microspheres or Fluoro-gold in the primary
somatosensory cortex of animals at different stages of
development revealed the existence of retrogradely labeled
neurons in the rostral and dorsal subdivisions of the zona
incerta from postnatal day 1. At this age, retrogradely
labeled cells were also found in the ventral lateral,
ventral posterior medial, posterior medial, centrolateral,
ventral medial and magnocellular subdivision of the medial
geniculate nuclei of the dorsal thalamus. The density of the
incertocortical projection reaches its maximum between the
first and second postnatal weeks, decreasing subsequently,
until an adult pattern of labeling is achieved. Tracer
injections combined with immunohistochemistry revealed that
the majority of the incertocortical projection derives from
GABAergic neurons, implying a potentially inhibitory role
for the incertocortical projection. These results
demonstrate that the rat trigeminal system contains parallel
thalamocortical pathways of opposite polarity, emerging from
both the dorsal (glutamatergic, excitatory) and ventral
(GABAergic, inhibitory) thalamus since the day of birth. As
such, these findings suggest that, contrary to the classical
notion, not only the dorsal but also the ventral thalamus
may play a special role in both cortical maturation and
function.},
Key = {fds114894}
}
@article{fds114914,
Title = {Nicolelis MAL, Baccala LA, Lin RCS, Chapin JK (1995)
Sensorimotor encoding by synchronous neural ensemble
activity at multiple levels of the somatosensory system.
Science 268: 1353-1358.},
Year = {1995},
Key = {fds114914}
}
@article{fds114916,
Title = {Nicolelis MAL, Chapin JK, Lin RCS (1995) Development of
the direct projections from the zona incerta to the primary
somatosensory cortex in rats. Neurosci 65:
609-631.},
Year = {1995},
Key = {fds114916}
}
@article{fds114917,
Title = {Chapin JK, Nicolelis MAL (1995) Beyond single unit
recording: Characterizing neural information in networks of
simultaneously recorded neurons. In: Scale in Conscious
Experience, eds. J. King and K.H. Pribram. Lawrence
Erlbaum Assoc., New Jersey, pp. 133-153.},
Year = {1995},
Key = {fds114917}
}
@article{fds114945,
Author = {MA Nicolelis and JK Chapin},
Title = {Spatiotemporal structure of somatosensory responses of
many-neuron ensembles in the rat ventral posterior medial
nucleus of the thalamus.},
Journal = {The Journal of neuroscience : the official journal of the
Society for Neuroscience, UNITED STATES},
Volume = {14},
Number = {6},
Pages = {3511-32},
Year = {1994},
Month = {June},
ISSN = {0270-6474},
Keywords = {Anesthesia • Animals • Brain Mapping • Cell
Aggregation • Computer Graphics • Evoked
Potentials, Somatosensory* • Neurons • Physical
Stimulation • Rats • Rats, Inbred Strains •
Reaction Time • Thalamic Nuclei • Vibrissae •
Wakefulness • physiology • physiology*},
Abstract = {Classically, the rat ventral posterior medial (VPM) nucleus
of the thalamus has been considered as a simple passive
relay for single-whisker information to the primary
somatosensory cortex (SI). However, recent reports have
suggested that the VPM could contain a much more coarsely
coded and spatiotemporally complex representation of the rat
whisker pad. To address this possibility properly, we have
carried out chronic simultaneous recordings of large numbers
(up to 23) of single neurons, distributed across the entire
VPM, in both awake and lightly anesthetized adult rats.
Quantitative, computer-based reconstruction of receptive
fields (RFs) revealed that single VPM neurons exhibit
significant responses to discrete stimulation of as many as
20 single whiskers (mean +/- SD RF size, 13.7 +/- 4.8
whiskers). By defining multiple response magnitude (RM)
thresholds it was possible to subdivide these large VPM RFs
quantitatively into a prominent center (mean +/- SD, 1.41
+/- 0.70 whiskers, RM > 95%) and an excitatory surround (up
to 18 whiskers, RM < 95%). VPM neurons exhibited both
short-latency responses (SLRs, from 4 to 10 msec
poststimulus) and/or long-latency responses (LLRs, 15-25
msec), each followed by inhibitory responses. Though LLRs
were weaker (mean +/- SD, 47.19 +/- 33.34 Hz) than SLRs
(119.63 +/- 50.12 Hz), they often defined RFs that differed
considerably from those defined by the SLRs of the same
cell. In particular, VPM cells with short-latency RFs
centered in caudal whiskers (e.g., C1, D1, E1) showed a
poststimulus time-dependent shift of these RF centers toward
the rostral whiskers (e.g., C4, D4, E4). These
caudal-to-rostral (C-->RF shifts occurred in neurons with
the largest RFs of our sample (17.2 +/- 2.4 whiskers). On
the other hand, VPM cells with short-latency RFs centered in
rostral whiskers had the smallest RFs (13.1 +/- 4.1
whiskers) and usually did not exhibit time-dependent RF
center shifts. Multivariate analysis revealed that these two
groups of VPM neurons, C-->R shifting and rostral position
(RP) cells, could be statistically distinguished according
to a combination of three RF attributes (short-latency RF
center location, RF size, and magnitude of RF center shift).
Quantitative, computer-based reconstruction of "population
response maps" demonstrated that the "place" coding for each
single whisker in the VPM involved a distinct weighted
contribution from a large proportion of the simultaneously
recorded neurons.(ABSTRACT TRUNCATED AT 400
WORDS)},
Key = {fds114945}
}
@article{fds114871,
Title = {Bennett-Clarke CA, Nicolelis MAL, Jacquin MF (1994)
Proceedings of a satellite symposium of the 1993 Society for
Neuroscience Meeting. Somat Mot Res 11: 197-204.},
Year = {1994},
Key = {fds114871}
}
@article{fds114913,
Title = {Nicolelis MAL, Chapin JK (1994) Spatiotemporal structure of
somatosensory responses of many-neuron ensembles in the rat
ventral posterior medial nucleus of the thalamus. J Neurosci
14: 3511-3532.},
Year = {1994},
Key = {fds114913}
}
@article{fds114959,
Author = {JJ Arends and CA Bennett-Clarke and MF Jacquin and MA Nicolelis and PJ
Shortland},
Title = {Barrels VI: proceedings of a satellite symposium of the 1993
Society for Neuroscience meeting.},
Journal = {Somatosensory & motor research, UNITED STATES},
Volume = {11},
Number = {3},
Pages = {197-204},
Year = {1994},
ISSN = {0899-0220},
Keywords = {Age Factors • Animals • Brain Mapping •
Cerebral Cortex • Neural Pathways • Rats •
Somatosensory Cortex • Thalamic Nuclei •
Trigeminal Nuclei • Vibrissae • innervation*
• physiology • physiology*},
Key = {fds114959}
}
@article{fds114906,
Author = {MA Nicolelis and RC Lin and DJ Woodward and JK Chapin},
Title = {Dynamic and distributed properties of many-neuron ensembles
in the ventral posterior medial thalamus of awake
rats.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America, UNITED STATES},
Volume = {90},
Number = {6},
Pages = {2212-6},
Year = {1993},
Month = {March},
ISSN = {0027-8424},
Keywords = {Animals • Electrophysiology • Models, Neurological
• Neurons • Physical Stimulation • Rats
• Thalamus • Vibrissae • Wakefulness •
innervation • methods • physiology •
physiology*},
Abstract = {The traditional view that the map of the face in the ventral
posterior medial thalamus (VPM) is static and highly
discrete was derived largely from qualitative studies that
reported only small, robust, and nonoverlapping receptive
fields (RFs). Here, by using more quantitative techniques,
we have provided evidence for an alternative hypothesis: the
RFs in the VPM are large and overlapping and tend to shift
as a function of post-stimulus time. These results were
obtained through simultaneous recordings of up to 23 single
neurons across the whisker representation in the VPM of
rats. Under both awake and anesthetized conditions, these
neurons responded robustly at short (4-6 ms) and/or long
(15-25 ms) latencies to discrete vibromechanical stimulation
of single facial whiskers. Computer graphics were used to
construct three-dimensional plots depicting the magnitudes
of neuronal responses to stimulation of each of several
whiskers as a function of post-stimulus time. These
"spatiotemporal RFs" demonstrated that (i) the RFs of VPM
neurons are quite large, covering up to 20 whiskers and (ii)
the spatial locations of these RFs may shift dramatically
over the first 35 ms of post-stimulus time, especially from
the caudal-most to the rostral-most whiskers on the face.
These results suggest that the VPM contains a dynamic and
distributed representation of the face, in which stimulus
information is coded in both spatial and temporal
domains.},
Key = {fds114906}
}
@article{fds114962,
Author = {MA Nicolelis and RC Lin and DJ Woodward and JK Chapin},
Title = {Induction of immediate spatiotemporal changes in thalamic
networks by peripheral block of ascending cutaneous
information.},
Journal = {Nature, ENGLAND},
Volume = {361},
Number = {6412},
Pages = {533-6},
Year = {1993},
Month = {February},
ISSN = {0028-0836},
Keywords = {Animals • Evoked Potentials • Lidocaine •
Nerve Net • Neuronal Plasticity • Rats •
Reaction Time • Sensory Deprivation • Thalamus
• pharmacology • physiology •
physiology*},
Abstract = {Peripheral sensory deprivation induces reorganization within
the somatosensory cortex of adult animals. Although most
studies have focused on the somatosensory cortex, changes at
subcortical levels (for example the thalamus) could also
play a fundamental role in sensory plasticity. To
investigate this, we made chronic simultaneous recordings of
large numbers of single neurons across the ventral posterior
medial thalamus (VPM) in adult rats. This allowed a
continuous and quantitative evaluation of the receptive
fields of the same sample of single VPM neurons per animal,
before and after sensory deprivation. Local anaesthesia in
the face induced an immediate and reversible reorganization
of a large portion of the VPM map. This differentially
affected the short latency (4-6 ms) responses (SLRs) and
long latency (15-25 ms) responses (LLRs) of single VPM
neurons. The SLRs and LLRs normally define spatiotemporally
complex receptive fields in the VPM. Here we report that 73%
of single neurons whose original receptive fields included
the anaesthetized zone showed immediate unmasking of SLRs in
response to stimulation of adjacent cutaneous regions,
and/or loss of SLRs with preservation or enhancement of LLRs
in response to stimulation of regions just surrounding the
anaesthetized zone. This thalamic reorganization
demonstrates that peripheral sensory deprivation may induce
immediate plastic changes at multiple levels of the
somatosensory system. Further, its spatiotemporally complex
character suggests a disruption of the normal dynamic
equilibrium between multiple ascending and descending
influences on the VPM.},
Key = {fds114962}
}
@article{fds114869,
Title = {Nicolelis MAL, Lin RCS, Woodward DJ, Chapin JK (1993)
Peripheral block of ascending cutaneous information induces
immediate spatiotemporal changes in thalamic networks.
Nature 361: 533-536.},
Year = {1993},
Key = {fds114869}
}
@article{fds114912,
Title = {Nicolelis MAL, Lin RCS, Woodward DJ, Chapin JK (1993)
Dynamic and distributed properties of many-neuron ensembles
in the ventral posterior medial (VPM) thalamus of awake
rats. Proc Natl Acad Sci USA 90: 2212-2216.},
Year = {1993},
Key = {fds114912}
}
@article{fds114963,
Author = {MA Nicolelis and JK Chapin and RC Lin},
Title = {Somatotopic maps within the zona incerta relay parallel
GABAergic somatosensory pathways to the neocortex, superior
colliculus, and brainstem.},
Journal = {Brain research, NETHERLANDS},
Volume = {577},
Number = {1},
Pages = {134-41},
Year = {1992},
Month = {April},
ISSN = {0006-8993},
Keywords = {Afferent Pathways • Animals • Brain Mapping •
Brain Stem • Cerebral Cortex •
Immunohistochemistry • Rats • Somatosensory Cortex
• Superior Colliculus • Thalamus • anatomy &
histology • anatomy & histology* •
gamma-Aminobutyric Acid • methods* •
physiology*},
Abstract = {Neurons located in the zona incerta (ZI) of the ventral
thalamus project to several regions of the central nervous
system, including the neocortex, superior colliculus, and
brainstem. However, whether these projections are
functionally segregated remains unknown. This issue was
addressed here by combining neuroanatomical tracers with
immunohistochemical staining for gamma-aminobutyric acid
(GABA) and/or parvalbumin, coupled with neurophysiological
mapping. GABAergic projection neurons were found in four
distinct subregions of the ZI including: (1) the rostral
pole of the ZI, from which neurons project to the
supragranular layers of the neocortex (especially layer I);
(2) the dorsal subregion of the ZI, where both ascending
projections to the neocortex and descending projections to
the pretectal area were observed; (3) the ventral subregion
of the ZI, whose neurons project to the superior colliculus;
and 3) the caudal pole of the ZI, from which descending
projections to the lower brainstem and spinal cord were
observed. Somatotopic representations of the contralateral
cutaneous periphery were also identified in the dorsal and
ventral subregions of ZI, both of which were found to
receive dense direct afferent projections from the
trigeminal complex, and dorsal column nuclei. These results
suggest that the rat ZI is a major somatosensory relay in
the ventral thalamus, carrying feed-forward inhibitory
signals to neocortical and subcortical targets, in parallel
with the excitatory somatosensory pathways.},
Key = {fds114963}
}
@article{fds114896,
Author = {MA Nicolelis and JK Chapin and RC Lin},
Title = {Neonatal whisker removal in rats stabilizes a transient
projection from the auditory thalamus to the primary
somatosensory cortex.},
Journal = {Brain research, NETHERLANDS},
Volume = {567},
Number = {1},
Pages = {133-9},
Year = {1991},
Month = {December},
ISSN = {0006-8993},
Keywords = {Aging • Animals • Animals, Newborn • Auditory
Cortex • Axonal Transport • Fluorescent Dyes
• Functional Laterality • Rats •
Somatosensory Cortex • Thalamus • Vibrissae •
anatomy & histology • growth & development •
innervation • physiology*},
Abstract = {A normally transient cross-modal thalamocortical projection
from the magnocellular subdivision of the medial geniculate
nucleus (MGm) to the primary somatosensory (SI) cortex of
rats was found to remain unchanged throughout adulthood
following unilateral removal of whiskers in newborn animals.
The normal MGm projection to the auditory cortex is not lost
in these neonatally whisker-deprived adults rats but some of
the MGm neurons send collaterals to both primary auditory
and SI cortices. Parallel electrophysiological experiments
demonstrated the multimodal character of some MGm neurons,
since they responded to both auditory and cutaneous
stimulation. These results suggest that the areal
distribution in the cortex of thalamocortical projections
arising from a multimodal thalamic nucleus, such as the MGm,
may be determined during early postnatal development by the
normal flow of sensory information from the periphery to the
thalamus and that an early postnatal somatosensory
deprivation may prevent the normal withdrawal of a
cross-modal projection from the MGm to the
SI.},
Key = {fds114896}
}
@article{fds114904,
Author = {MA Nicolelis and JK Chapin and RC Lin},
Title = {Thalamic plasticity induced by early whisker removal in
rats.},
Journal = {Brain research, NETHERLANDS},
Volume = {561},
Number = {2},
Pages = {344-9},
Year = {1991},
Month = {October},
ISSN = {0006-8993},
Keywords = {Aging • Animals • Animals, Newborn •
Mechanoreceptors • Neuronal Plasticity* • Neurons
• Rats • Rats, Inbred Strains • Reference
Values • Skin • Thalamus • Vibrissae •
growth & development • innervation* • physiology
• physiology*},
Abstract = {Neurophysiological mapping was used to study the effects of
early postnatal removal of mystacial whiskers on the
organization of cutaneous receptive fields (RFs) within the
ventral posterior thalamus (VP) of rats. This sensory
deprivation induced an extensive reorganization of the
thalamus, as reflected in larger facial or continuous
overlapping face-body RFs and a higher proportion of
slowly-adapting responses. Mapping of the VP of young rats
(2-3 weeks old) demonstrated that the functional
organization of the immature VP thalamus resembles that of
the sensory-deprived VP, suggesting that an early postnatal
sensory deprivation may interfere with the normal process of
thalamic development.},
Key = {fds114904}
}
@article{fds114908,
Author = {CS Lin and MA Nicolelis and JS Schneider and JK Chapin},
Title = {GABAergic pathway from zona incerta to neocortex:
clarification.},
Journal = {Science (New York, N.Y.), UNITED STATES},
Volume = {251},
Number = {4998},
Pages = {1162},
Year = {1991},
Month = {March},
ISSN = {0036-8075},
Keywords = {Animals • Axonal Transport • Cerebral Cortex
• Diencephalon • Horseradish Peroxidase •
Mice • Neurons • Rats • Thalamus •
anatomy & histology* • cytology •
gamma-Aminobutyric Acid • physiology*},
Key = {fds114908}
}
@article{fds114899,
Author = {LA Baccala and MA Nicolelis and CH Yu and M Oshiro},
Title = {Structural analysis of neural circuits using the theory of
directed graphs.},
Journal = {Computers and biomedical research, an international journal,
UNITED STATES},
Volume = {24},
Number = {1},
Pages = {7-28},
Year = {1991},
Month = {February},
ISSN = {0010-4809},
Keywords = {Animals • Models, Biological* • Nerve Net •
Software • Vertebrates • physiology*},
Abstract = {A new approach to analysis of structural properties of
biological neural circuits is proposed based on their
representation in the form of abstract structures called
directed graphs. To exemplify this methodology, structural
properties of a biological neural network and randomly wired
circuits (RC) were compared. The analyzed biological circuit
(BC) represented a sample of 39 neural nuclei which are
responsible for the control of the cardiovascular function
in higher vertebrates. Initially, direct connections of both
circuits were stored in a square matrix format. Then,
standard algorithms derived from the theory of directed
graphs were applied to analyze the pathways of the circuits
according to their length (in number of synapses), degree of
connectedness, and structural strength. Thus, the BC was
characterized by the presence of short, reciprocal, and
unidirectional pathways which presented a high degree of
heterogeneity in their strengths. This heterogeneity was
mainly due to the existence of a small cluster of
reciprocally connected neural nuclei in the circuit that
have access, through short pathways, to most of the network.
On the other hand, RCs were characterized by the presence of
long and mainly reciprocal pathways which showed lower and
absolute homogeneous strengths. Through this study the
proposed methodology was demonstrated to be a simple and
efficient way to store, analyze, and compare basic
neuroanatomical information.},
Key = {fds114899}
}
@article{fds114892,
Author = {MA Nicolelis and JK Chapin and CS Lin},
Title = {Ontogeny of corticocortical projections of the rat
somatosensory cortex.},
Journal = {Somatosensory & motor research, UNITED STATES},
Volume = {8},
Number = {3},
Pages = {193-200},
Year = {1991},
ISSN = {0899-0220},
Keywords = {Aging • Animals • Caudate Nucleus • Cerebral
Cortex • Corpus Callosum • Dominance, Cerebral
• Neural Pathways • Neurons • Putamen •
Rats • Somatosensory Cortex • Thalamic Nuclei
• anatomy & histology • anatomy & histology*
• physiology* • ultrastructure},
Abstract = {Rhodamine-coated microspheres (RCMs) were injected into the
primary somatosensory cortex (SI) of rats ranging in age
from postnatal (PN) day 1 to adulthood. Ipsilateral
corticocortical and callosal projections within the SI were
identified as early as PN day 1. At the end of the first PN
week, ipsilaterally projecting neurons located in sublayer
VIb were the first to assume an adult-like pattern of
connectivity. Injections at subsequent postnatal ages
revealed that an adult pattern of lamination of ipsilateral
corticocortical projections within the SI is established
between PN weeks 2 and 3, comprising projection neurons from
layers II/III, layer V, and sublayer VIb. Therefore, local
interactions in the rat SI are mediated not only by
pyramidal neurons of layers III and V, derived from the
cortical plate, but also by a subpopulation of
ontogenetically older neurons located in the sublayer VIb,
which may correspond to the subplate neurons of other
species. Overall, these results suggest the existence of
three independent short-range corticocortical systems of
projections within the rat SI, which differ in terms of the
laminar distribution and ontogenetic origin of their
cells.},
Key = {fds114892}
}
@article{fds114895,
Author = {MA Nicolelis and LA Baccala},
Title = {Rhythmic bacterial susceptibility to antibiotics at a large
hospital.},
Journal = {Journal of clinical epidemiology, ENGLAND},
Volume = {44},
Number = {2},
Pages = {191-205},
Year = {1991},
ISSN = {0895-4356},
Keywords = {Anti-Bacterial Agents • Bacteria • Bacterial
Infections • Cross Infection • Escherichia coli
• Humans • Klebsiella pneumoniae • Proteus
mirabilis • Pseudomonas aeruginosa • Species
Specificity • Staphylococcus aureus • drug effects
• drug effects* • microbiology* •
pharmacology*},
Abstract = {The in vitro susceptibility response of Staphylococcus
aureus, Klebsiella pneumoniae, Escherichia coli, Proteus
mirabilis and Pseudomonas aeruginosa to a set of antibiotics
was investigated in a survey comprising 19,380 positive
cultures over a period of 5 years in a large hospital
environment. Four out of the five species (P. aeruginosa
being the exception) presented a species-specific,
drug-independent, rhythmic variation of their level of
susceptibility to several antibiotics over the time of the
study. The species-specific rhythmic responses were further
characterized by spectral analysis, autocorrelation and
cross-correlation functions. Through this analysis it was
possible to rank the species according to their main period
of oscillation. The longest period of oscillation was
detected for S. aureus (38 months). K. pneumoniae and E.
coli presented intermediate values (25 and 23 months
respectively), and P. mirabilis the shortest period of
oscillation (11 months). Species displaying long periods of
oscillation tended to present very low levels of
susceptibility, while species displaying short periods of
oscillation usually presented the highest levels of
susceptibility observed. Although some hospital
environmental factors, such as drug consumption, were also
analyzed, no correlation was found between them and the in
vitro bacterial cyclic responses to antibiotics.},
Key = {fds114895}
}
@article{fds114969,
Author = {CS Lin and MA Nicolelis and JS Schneider and JK Chapin},
Title = {A major direct GABAergic pathway from zona incerta to
neocortex.},
Journal = {Science (New York, N.Y.), UNITED STATES},
Volume = {248},
Number = {4962},
Pages = {1553-6},
Year = {1990},
Month = {June},
ISSN = {0036-8075},
Keywords = {Animals • Cerebral Cortex • Diencephalon •
Dopamine • Glutamate Decarboxylase •
Immunohistochemistry • Neural Pathways • Neurons
• Rats • analysis • enzymology •
gamma-Aminobutyric Acid • physiology •
physiology*},
Abstract = {Retrograde fluorescent tracers were used to demonstrate a
previously unknown but sizable direct gamma-aminobutyric
acid (GABA)-containing neuronal pathway from the zona
incerta to the neocortex in rats. This incertocortical
pathway was found to project bilaterally to the entire
neocortex and exhibited a rough corticotopic organization.
Many of the zona incerta neurons projecting to the parietal
and occipital cortices could also be immunohistochemically
stained with antibodies to glutamic acid decarboxylase and
GABA. Few of these neurons were immunoreactive to tyrosine
hydroxylase antibodies, which identify dopamine-containing
neurons. Injections in the frontal and entorhinal cortices
labeled many neurons near or within the dopaminergic A13
subdivision of the zona incerta. In addition, the
incertocortical system was found to be significantly larger
during early postnatal (2 to 3 weeks) development. The
projection pattern of this newly discovered pathway
resembles that of the monoaminergic and cholinergic systems,
arising from the brainstem and forebrain, suggesting
possible similarities of function.},
Key = {fds114969}
}
@article{fds114948,
Author = {MA Nicolelis and G Tinone and K Sameshima and C Timo-Iaria and CH Yu and MT
Van de Bilt},
Title = {Connection, a microcomputer program for storing and
analyzing structural properties of neural
circuits.},
Journal = {Computers and biomedical research, an international journal,
UNITED STATES},
Volume = {23},
Number = {1},
Pages = {64-81},
Year = {1990},
Month = {February},
ISSN = {0010-4809},
Keywords = {Algorithms • Cardiovascular System • Information
Systems • Microcomputers* • Models, Neurological*
• Neural Pathways • Software Design •
Software* • anatomy & histology* •
innervation*},
Abstract = {The application of a microcomputer-based system (the
Connection system) designed to deal with neuroanatomical
information commonly analyzed by researchers and involved in
the study of structural properties of neural circuits is
presented. This system can be employed at first as a
readily-accessible database containing physiological and
anatomical data from nuclei of the central nervous system
which define a network with up to 45 elements and their
subdivisions and connections. Once the database from a
specific network is built and stored in a file, routines of
this system can be used to classify the nuclei in term of
their afferents and efferents and also to display all
possible pathways linking any pair of nuclei and their
respective length (number of synapses). The role of such a
system as an auxiliary tool in neuroanatomical and
electrophysiological research is discussed by presenting the
results obtained from the analysis of the neural circuits
involved in cardiovascular function control in higher
vertebrates.},
Key = {fds114948}
}
@article{fds114911,
Title = {Lin CS, Nicolelis MAL, Schneider JS, Chapin JK (1990) A
major direct GABAergic pathway from zona incerta to
neocortex. Science 248: 1553-1556.},
Year = {1990},
Key = {fds114911}
}
@article{fds114950,
Author = {MA Nicolelis and CH Yu and LA Baccala},
Title = {Structural characterization of the neural circuit
responsible for control of cardiovascular functions in
higher vertebrates.},
Journal = {Computers in biology and medicine, UNITED
STATES},
Volume = {20},
Number = {6},
Pages = {379-400},
Year = {1990},
ISSN = {0010-4825},
Keywords = {Animals • Cardiovascular System • Cluster Analysis
• Computer Simulation* • Microcomputers •
Models, Biological* • Nerve Net • Vertebrates
• innervation* • physiology*},
Abstract = {A comparison of structural properties of a biological neural
system responsible for cardiovascular function control in
higher vertebrates with randomly connected networks was
pursued using matrix representations of those circuits. The
biological circuit was characterized by the presence of some
heavily connected nuclei in contrast to the random networks
that had equally distributed connections between their
elements. This property of the analysed biological circuit
was shown to account for a high logarithmic correlation
found between two indexes defined to represent pointwise
features of the nuclei and their global contribution to the
whole network. The first index is obtained by the product of
the number of inputs and of outputs of a nucleus and was
called power index (PI). The second one, called occurrence
index (OI), defines how many times a specific nucleus is
crossed when all possible pathways joining two nuclei of the
circuit are obtained. This PI-OI correlation was clearly
dependent on the pathway length distribution (expressed in
number of synapses), and was maximal considering pathways
with a low number of synapses. When randomly connected
circuits were analysed lower correlation was found between
the same two indexes and only for much longer pathways.
Therefore, it is proposed that the analysis of the PI-OI
correlation can be useful to quantify structural differences
between biological neural circuits as distinguished from
randomly connected networks and also between neural systems
at different levels of phylogenetic and ontogenetic
development.},
Key = {fds114950}
}
@article{fds114956,
Author = {GS Montes and MA Nicolelis and HP Brentani-Samaia and SS
Furuie},
Title = {Collagen fibril diameters in arteries of mice. A comparison
of manual and computer-aided morphometric
analyses.},
Journal = {Acta anatomica, SWITZERLAND},
Volume = {135},
Number = {1},
Pages = {57-61},
Year = {1989},
ISSN = {0001-5180},
Keywords = {Animals • Arteries • Collagen • Female •
Histocytochemistry • Image Processing,
Computer-Assisted* • Male • Mice •
Microscopy, Electron • ultrastructure*},
Abstract = {Arteries of mice were studied by a silver impregnation
technique, by the Picrosirius-polarization method and by
transmission electron microscopy. The histochemical results
obtained coincided with the electron-microscopic
observations in showing the presence of two distinct
collagen populations, segregated into different compartments
of each artery. The fibrous component of the tunica media
was comprised of reticulin fibers, which displayed a
distinct argyrophilia when studied by means of the silver
impregnation technique, and showed up as thin, weakly
birefringent, greenish fibers when examined with the aid of
the Picrosirius-polarization method. In addition, the
electron-microscopic studies disclosed the presence of thin
collagen fibrils in the tunica media, contrasting with the
thicker fibrils that could be localized ultrastructurally to
the tunica adventitia where nonargyrophil, coarse collagen
fibers had been characterized by the histochemical methods
used. In this respect, collagen distribution in arteries of
mice is very similar to the pattern that was consistently
observed in the other species studied, which argues in favor
of the existence of a uniform structural pattern of collagen
distribution that is a general phenomenon in vertebrate
arteries. Experimental results comparing the traditional
method and the computer-aided measurement of collagen fibril
diameters showed that the system provides results equivalent
to those produced by manual execution. In addition, the
advantage in speed of the computer-aided method should prove
useful in complicated studies where numerous structures are
involved.},
Key = {fds114956}
}
@article{fds114901,
Author = {MA Nicolelis and LA Baccala},
Title = {Do bacteria have an intrinsic rhythmic sensitivity
pattern?},
Journal = {Critical care medicine, UNITED STATES},
Volume = {16},
Number = {6},
Pages = {650},
Year = {1988},
Month = {June},
ISSN = {0090-3493},
Keywords = {Microbial Sensitivity Tests* • Periodicity},
Key = {fds114901}
}
@article{fds114968,
Author = {MA Nicolelis and LA Baccala},
Title = {Time series analysis of rhythmic bacterial resistance
development to antibiotics.},
Journal = {Computers and biomedical research, an international journal,
UNITED STATES},
Volume = {21},
Number = {2},
Pages = {137-57},
Year = {1988},
Month = {April},
ISSN = {0010-4809},
Keywords = {Analysis of Variance • Data Interpretation,
Statistical* • Drug Resistance, Microbial* •
Escherichia coli • Fourier Analysis • Periodicity*
• Staphylococcus aureus • Time Factors • drug
effects},
Abstract = {The sensitivity data of Staphylococcus aureus and
Escherichia coli to a large set of antibiotics have
undergone time series procedures of analysis in order to
highlight possibly periodical behavior in time. These
oscillational patterns have been characterized through the
use of FFT and cross-correlational and variance analysis and
were proved to be species-specific and drug-independent. S.
aureus was shown to have a large period of oscillation (40
months) when compared to E. coli (from 7 to 11 months). A
perfect species distinction was only possible through cross
correlation. These results may reflect the influence of the
local environment, since this finding was not referred to in
the literature.},
Key = {fds114968}
}
@article{fds114898,
Author = {E Massad and AB Engel and MA Nicolelis},
Title = {A mathematical model for spirometry.},
Journal = {Computers and biomedical research, an international journal,
UNITED STATES},
Volume = {20},
Number = {2},
Pages = {105-12},
Year = {1987},
Month = {April},
ISSN = {0010-4809},
Keywords = {Animals • Humans • Microcomputers • Models,
Theoretical* • Plethysmography, Whole Body • Rats
• Rats, Inbred Strains • Spirometry*},
Abstract = {A model originally designed to fit population growth data
was investigated to determine whether it could fit
spirometric traces as a function of time in normal and ill
humans and in normal rats, obtained, respectively, by
spirometer and whole-body plethysmography. The model showed
great accuracy when applied to a simple spirometer coupled
with an analog-to-digital converter interfaced with a
personal computer. It also proved to be a good alternative
for the more expensive and less accurate electronic devices,
as derivative systems, and may be an attractive method for
research and/or diagnostic centers.},
Key = {fds114898}
}
@article{fds114961,
Author = {MA Nicolelis and E Massad and RU Hutzler and A Engel and E Rodrigues and JC
Bazzone, M Tomida},
Title = {Mathematical model of Klebsiella pneumoniae resistance to
amikacin and gentamicin.},
Journal = {Brazilian journal of medical and biological research =
Revista brasileira de pesquisas médicas e biológicas /
Sociedade Brasileira de Biofísica ... [et al.],
BRAZIL},
Volume = {20},
Number = {1},
Pages = {35-41},
Year = {1987},
ISSN = {0100-879X},
Keywords = {Amikacin • Drug Resistance, Microbial •
Gentamicins • Klebsiella pneumoniae • Microbial
Sensitivity Tests • Models, Theoretical • drug
effects* • pharmacology*},
Abstract = {1. The resistance of Klebsiella pneumoniae to amikacin and
gentamicin was studied by a mathematical model to predict
the rate of sensitivity decrease. The results accurately
matched experimental data, showing that the model is a
reliable predicting tool. 2. The observations were carried
out over six years and included 2677 cultures that were
positive for K. pneumoniae. At the beginning of the
observation period, 85.7% of the cultures were sensitive to
amikacin and 40.8% were sensitive to gentamicin. Sensitivity
to amikacin showed a surprisingly rapid decrease; at the end
of the experimental period, amikacin and gentamicin
sensitivities were 33.3% and 27.8%, respectively. 3. We
conclude that patterns of resistance of other bacteria could
be investigated using this method.},
Key = {fds114961}
}
@article{fds114967,
Author = {E Massad and SS Furuie and Lde A Moura Júnior and PH Saldiva and MA
Nicolelis, GM Böhm},
Title = {The use of a personal computer in the pulmonary function
tests of laboratory rats.},
Journal = {Methods of information in medicine, GERMANY,
WEST},
Volume = {24},
Number = {4},
Pages = {197-9},
Year = {1985},
Month = {October},
ISSN = {0026-1270},
Keywords = {Animals • Automatic Data Processing* • Computers*
• Microcomputers* • Plethysmography • Rats
• Rats, Inbred Strains • Respiratory Function
Tests • instrumentation*},
Key = {fds114967}
}
@article{fds114966,
Author = {PH Saldiva and E Massad and MP Caldeira and DF Calheiros and CD Saldiva and MA Nicolelis and GM Böhm},
Title = {Pulmonary function of rats exposed to ethanol and gasoline
fumes.},
Journal = {Brazilian journal of medical and biological research =
Revista brasileira de pesquisas médicas e biológicas /
Sociedade Brasileira de Biofísica ... [et al.],
BRAZIL},
Volume = {18},
Number = {4},
Pages = {573-7},
Year = {1985},
ISSN = {0100-879X},
Keywords = {Animals • Ethanol • Gasoline • Lung •
Male • Petroleum • Rats • Rats, Inbred
Strains • Respiratory Function Tests • Vehicle
Emissions • drug effects* • physiopathology •
toxicity*},
Abstract = {This paper describes the effects of repeated exposure to
gasoline and ethanol exhaust fumes on the pulmonary
mechanics of rats assessed by whole-body plethysmography.
Two groups of 12 male Wistar albino rats each were tested
before and after exposure to diluted gasoline or ethanol
exhaust gases for 5 weeks, 8 h per day and 5 days per week.
An additional group of 12 rats were exposed to clean air
under the same experimental conditions. The variations of
the functional parameters observed in the three groups
before and after exposure were compared. Peak Expiratory
Flow and Forced Expiratory Mean Flows in the ranges 0-25%,
25-50% and 50-75% of Forced Vital Capacity were
significantly reduced in animals exposed to gasoline exhaust
fumes, whereas the group exposed to ethanol exhaust fumes
did not differ from the control group. This respiratory
impairment is probably due to the presence of SO2 and the
quality of the hydrocarbons in gasoline exhaust
gases.},
Key = {fds114966}
}
@article{fds114900,
Author = {MA Nicolelis and D Katz and DJ Krupa},
Title = {Potential circuit mechanisms underlying concurrent thalamic
and cortical plasticity.},
Journal = {Reviews in the neurosciences, ENGLAND},
Volume = {9},
Number = {3},
Pages = {213-24},
ISSN = {0334-1763},
Keywords = {Animals • Cerebral Cortex • Humans • Neural
Pathways • Neuronal Plasticity • Sensation •
Thalamus • physiology • physiology*},
Abstract = {During the last two decades, plastic reorganization of both
sensory and motor representations in the adult central
nervous system has been demonstrated following a large
variety of manipulations, ranging from partial lesions of
the sensory receptor surface to modifications in sensory
experience (see /14/ for review). Yet, little is known about
the neural circuit mechanisms underlying such reorganization
process. Despite the difficulty in addressing this issue,
recent studies have provided some insights into this
fundamental question. Altogether, these studies suggest that
the process of plastic reorganization is a system-wide
phenomenon, involving both cortical and subcortical
representations. Contrary to classical beliefs, recent work
also suggests that the final outcome of the reorganization
process is not necessarily beneficial, since it can lead to
abnormal perceptual experiences /31/, such as the phantom
limb sensation, and even pain /31,32/. In this review, we
focus on recent insights into the possible circuit
mechanisms underlying sensory plasticity and discuss the
potential implications of these findings. We then present
physiological evidence supporting the view that the process
of plasticity observed at the cortical level may reflect
simultaneous changes in many subcortical
structures.},
Key = {fds114900}
}
@article{fds114951,
Author = {MA Nicolelis and YC Hong},
Title = {Application of a microcomputer-based system in the analysis
of infection data at the emergency units of a large
hospital.},
Journal = {International journal of bio-medical computing,
ENGLAND},
Volume = {22},
Number = {3-4},
Pages = {183-98},
ISSN = {0020-7101},
Keywords = {Brazil • Computers* • Cross Infection •
Emergency Service, Hospital* • Escherichia coli
Infections • Hospital Information Systems* •
Humans • Klebsiella Infections • Microbial
Sensitivity Tests • Microcomputers* • Pseudomonas
Infections • Retrospective Studies • Software*
• Staphylococcal Infections • epidemiology •
epidemiology* • microbiology},
Abstract = {After three years of retrospective study in four emergency
units from a large hospital (2000 beds) and analysis of 6283
positive cultures, a microcomputer database system was built
to store information concerning nosocomial infections in
order to help the clinical staff from those units to study
the incidence of 20 bacterial species and their sensitivity
pattern evolutions for 27 antibiotics (from samples in 15
different collecting sites). This system was developed as an
alternative to the hospital mainframe computer
microbiological reports. It put emphasis on graphical
outputs instead of the coded tables generated by the bigger
system. This orientation and the possibility of sectorial
infection data analysis were responsible for the general
acceptance of the microcomputer-based system by the clinical
staff. As the first practical results, the system was able
to detect a particular increase in the incidence of
Staphylococcus aureus in surgical emergency units (up to
21.6% in 1982) as well as the dissemination of the
antimicrobial resistance patterns of S. aureus and
Klebsiella pneumoniae from the surgical units to the
clinical ones. The time evolution behaviour of Pseudomonas
aeruginosa, Escherichia coli and other nonfermentative Gram
negative bacilli was also studied to complete the analysis
of the most pathogenic bacterial species found in our
emergency units.},
Key = {fds114951}
}
@article{fds114965,
Author = {MA Nicolelis and MA Martins and LP Meireles and D
Birolini},
Title = {[Analysis of incidence patterns and bacterial sensitivity in
a surgical unit using microcomputers]},
Journal = {AMB; revista da Associação Médica Brasileira,
BRAZIL},
Volume = {32},
Number = {7-8},
Pages = {134-40},
ISSN = {0102-843X},
Keywords = {Anti-Bacterial Agents • Bacteria • Computers*
• Cross Infection • Humans • Microbial
Sensitivity Tests* • Microcomputers* • Operating
Rooms* • drug effects* • isolation & purification
• microbiology* • pharmacology*},
Key = {fds114965}
}
@article{fds114955,
Author = {MA Nicolelis and CR de Carvalho},
Title = {[Standardization of antimicrobial procedures using
computers]},
Journal = {Revista do Hospital das Clínicas, BRAZIL},
Volume = {40},
Number = {5},
Pages = {227-32},
ISSN = {0041-8781},
Keywords = {Anti-Bacterial Agents • Bacteria • Computers*
• Cross Infection • Drug Resistance, Microbial
• Humans • Microbial Sensitivity Tests •
Microcomputers* • drug effects* • pharmacology*
• prevention & control • standards*},
Key = {fds114955}
}
%% Papers Published
@article{071410526096,
Author = {Zachsenhouse, M. and Nemets, S. and Yoffe, A. and Ben-Haim,
Y. and Lebedev, Mikhail A. and Nicolelis, Miguel A.
L.},
Title = {An INFO-GAP approach to linear regression},
Journal = {ICASSP, IEEE International Conference on Acoustics, Speech
and Signal Processing - Proceedings},
Volume = {3},
Pages = {800-803 -},
Address = {Toulouse, France},
Year = {2006},
Keywords = {Mathematical models;Optimization;Parameter
estimation;Probability;Problem solving;Uncertainty
analysis;},
Abstract = {Linear regression with high uncertainties in the
measurements, model structure and model permanence is a
major challenging problem. Standard regression techniques
are based on optimizing a certain performance criterion,
usually the mean squared error, and are highly sensitive to
uncertainties. Regularization methods have been developed to
address the problem of measurement uncertainty, but choosing
the regularization parameter under severe uncertainties is
problematic. Here we develop an alternative regression
methodology based on satisficing rather than optimizing the
performance criterion while maximizing the robustness to
uncertainties. Uncertainties are represented by info-gap
models which entail an unbounded family of nested sets of
measurements parameterized by a non-probabilistic horizon of
uncertainty. We prove and demonstrate that the
robust-satisficing solution is different from the optimal
least squares solution and that the infogap approach can
provide higher robustness to uncertainty. © 2006
IEEE.},
Key = {071410526096}
}
@article{8927250,
Author = {Kim, H.K. and Biggs, J. and Schloerb, W. and Carmena, M. and Lebedev, M.A. and Nicolelis, M.A.L. and Srinivasan,
M.A.},
Title = {Continuous shared control for stabilizing reaching and
grasping with brain-machine interfaces},
Journal = {IEEE Trans. Biomed. Eng. (USA)},
Volume = {53},
Number = {6},
Pages = {1164 - 73},
Year = {2006},
url = {http://dx.doi.org/10.1109/TBME.2006.870235},
Keywords = {brain;handicapped aids;medical control systems;neurophysiology;prosthetics;telerobotics;},
Abstract = {Research on brain-machine interfaces (BMI's) is directed
toward enabling paralyzed individuals to manipulate their
environment through slave robots. Even for able-bodied
individuals, using a robot to reach and grasp objects in
unstructured environments can be a difficult
telemanipulation task. Controlling the slave directly with
neural signals instead of a hand-master adds further
challenges, such as uncertainty about the intended
trajectory coupled with a low update rate for the command
signal. To address these challenges, a continuous shared
control (CSC) paradigm is introduced for BMI where robot
sensors produce reflex-like reactions to augment
brain-controlled trajectories. To test the merits of this
approach, CSC was implemented on a 3-degree-of-freedom robot
with a gripper bearing three co-located range sensors. The
robot was commanded to follow eighty-three reach-and-grasp
trajectories estimated previously from the outputs of a
population of neurons recorded from the brain of a monkey.
Five different levels of sensor-based reflexes were tested.
Weighting brain commands 70% and sensor commands 30%
produced the best task performance, better than brain
signals alone by more than seven-fold. Such a marked
performance improvement in this test case suggests that some
level of machine autonomy will be an important component of
successful BMI systems in general},
Key = {8927250}
}
@article{9020704,
Author = {Kim, S.-P. and Sanchez, J.C. and Rao, Y.N. and Erdogmus, D. and Carmena, J.M. and Lebedev, M.A. and Nicolelis, M.A.L. and Principe, J.C.},
Title = {A comparison of optimal MIMO linear and nonlinear models for
brain-machine interfaces},
Journal = {J. Neural Eng. (UK)},
Volume = {3},
Number = {2},
Pages = {145 - 61},
Year = {2006},
url = {http://dx.doi.org/10.1088/1741-2560/3/2/009},
Keywords = {brain;delays;generalisation (artificial intelligence);medical
signal processing;MIMO systems;neural nets;neurophysiology;user
interfaces;Wiener filters;},
Abstract = {The field of brain-machine interfaces requires the
estimation of a mapping from spike trains collected in motor
cortex areas to the hand kinematics of the behaving animal.
This paper presents a systematic investigation of several
linear (Wiener filter, LMS adaptive filters, gamma filter,
subspace Wiener filters) and nonlinear models (time-delay
neural network and local linear switching models) applied to
datasets from two experiments in monkeys performing motor
tasks (reaching for food and target hitting). Ensembles of
100-200 cortical neurons were simultaneously recorded in
these experiments, and even larger neuronal samples are
anticipated in the future. Due to the large size of the
models (thousands of parameters), the major issue studied
was the generalization performance. Every parameter of the
models (not only the weights) was selected optimally using
signal processing and machine learning techniques. The
models were also compared statistically with respect to the
Wiener filter as the baseline. Each of the optimization
procedures produced improvements over that baseline for
either one of the two datasets or both},
Key = {9020704}
}
@article{8897550,
Author = {Kim, S.-P. and Rao, Y.N. and Erdogmus, D. and Sanchez, J.C. and Nicolelis, M.A.L. and Principe, J.C.},
Title = {Determining patterns in neural activity for reaching
movements using nonnegative matrix factorization},
Journal = {EURASIP J. Appl. Signal Process. (USA)},
Volume = {2005},
Number = {19},
Pages = {3113 - 21},
Year = {2005},
url = {http://dx.doi.org/10.1155/ASP.2005.3113},
Keywords = {brain;matrix decomposition;medical signal
processing;neurophysiology;spatiotemporal
phenomena;},
Abstract = {We propose the use of nonnegative matrix factorization (NMF)
as a model-independent methodology to analyze neural
activity. We demonstrate that, using this technique, it is
possible to identify local spatiotemporal patterns of neural
activity in the form of sparse basis vectors. In addition,
the sparseness of these bases can help infer correlations
between cortical firing patterns and behavior. We
demonstrate the utility of this approach using neural
recordings collected in a brain-machine interface (BMI)
setting. The results indicate that, using the NMF analysis,
it is possible to improve the performance of BMI models
through appropriate pruning of inputs},
Key = {8897550}
}
@article{8521262,
Author = {Sung-Phil Kim and Carmena, J.M. and Nicolelis, M.A. and Principe, J.C.},
Title = {Multiresolution representations and data mining of neural
spikes for brain-machine interfaces},
Journal = {2005 2nd International IEEE/EMBS Conference on Neural
Engineering (IEEE Cat. No.05EX938)},
Pages = {221 - 4},
Address = {Arlington, VA, USA},
Year = {2005},
Keywords = {bioelectric phenomena;biomechanics;brain;data
mining;handicapped aids;medical signal detection;neurophysiology;signal
representation;signal resolution;},
Abstract = {In brain-machine interface (BMI) applications, neural firing
activities have been represented by spike counts with a
fixed-width time bin. Adaptive models have been designed to
utilize these bin counts for mapping the associated behavior
which is typically 2D or 3D hand movement. However, the
representation of the firing activities can be enriched by
binning neural spikes with multiple time scales based on
multiresolution analysis. This multiresolution
representation of neural activities can provide more
accurate prediction of the hand movement parameters. Data
mining techniques must be applied to models using
multiresolution representation in order to avoid
over-fitting. In this paper, we demonstrate that the
multiresolution representation improves the performance of
the linear model for BMIs compared to the model with the
fixed-width time bin},
Key = {8521262}
}
@article{8571986,
Author = {Rao, Y.N. and Kim, S.-P. and Sanchez, J.C. and Erdogmus, D. and Principe, J.C. and Carmena, J.M. and Lebedev, M.A. and Nicolelis, M.A.},
Title = {Learning mappings in brain machine interfaces with echo
state networks},
Journal = {2005 IEEE International Conference on Acoustics, Speech, and
Signal Processing (IEEE Cat. No.05CH37625)},
Volume = {Vol. 5},
Pages = {233 - 6},
Address = {Philadelphia, PA, USA},
Year = {2005},
Keywords = {brain models;generalisation (artificial intelligence);learning
(artificial intelligence);multilayer perceptrons;neurophysiology;recurrent
neural nets;},
Abstract = {Brain machine interfaces (BMI) utilize linear or non-linear
models to map the neural activity to the associated behavior
which is typically the 2D or 3D hand position of a primate.
Linear models are plagued by the massive disparity of the
input and output dimensions thereby leading to poor
generalization. A solution would be to use non-linear models
like the recurrent multi-layer perceptron (RMLP) that
provide parsimonious mapping functions with better
generalization. However, this results in a drastic increase
in the training complexity, which can be critical for
practical use of a BMI. This paper bridges the gap between
superior performance per trained weight and model learning
complexity. Towards this end, we propose to use echo state
networks (ESN) to transform the neuronal firing activity
into a higher dimensional space and then derive an optimal
sparse linear mapping in the transformed space to match the
hand position. The sparse mapping is obtained using a weight
constrained cost function whose optimal solution is
determined using a stochastic gradient algorithm},
Key = {8571986}
}
@article{06229905160,
Author = {Rao, Yadunandana N. and Kim, Sung-Phil and Sanchez, Justin
C. and Erdogmus, Deniz and Principe, Jose C. and Carmena,
Jose M. and Lebedev, Mikhail A. and Nicolelis, Miguel
A.},
Title = {Learning mappings in brain machine interfaces with echo
state networks},
Journal = {ICASSP, IEEE International Conference on Acoustics, Speech
and Signal Processing - Proceedings},
Pages = {233-236 -},
Address = {Philadelphia, PA, United States},
Year = {2005},
Keywords = {Learning systems;Computer networks;Neural
networks;Mathematical models;Mapping;Computational
complexity;Random processes;},
Abstract = {Brain Machine Interfaces (BMI) utilize linear or non-linear
models to map the neural activity to the associated behavior
which is typically the 2-D or 3-D hand position of a
primate. Linear models are plagued by the massive disparity
of the input and output dimensions thereby leading to poor
generalization. A solution would be to use non-linear models
like the Recurrent Multi-Layer Perceptron (RMLP) that
provide parsimonious mapping functions with better
generalization. However, this results in a drastic increase
in the training complexity, which can be critical for
practical use of a BMI. This paper bridges the gap between
superior performance per trained weight and model learning
complexity. Towards this end, we propose to use Echo State
Networks (ESN) to transform the neuronal firing activity
into a higher dimensional space and then derive an optimal
sparse linear mapping in the transformed space to match the
hand position. The sparse mapping is obtained using a weight
constrained cost function whose optimal solution is
determined using a stochastic gradient algorithm. ©
2005 IEEE.},
Key = {06229905160}
}
@article{06239919050,
Author = {Kim, Sung-Phil and Carmena, Jose M. and Nicolelis, Miguel A. and Principe, Jose C.},
Title = {Multiresolution representations and data mining of neural
spikes for brain-machine interfaces},
Journal = {2nd International IEEE EMBS Conference on Neural
Engineering},
Volume = {2005},
Pages = {221 - 224},
Address = {Arlington, VA, United States},
Year = {2005},
url = {http://dx.doi.org/10.1109/CNE.2005.1419596},
Keywords = {Data mining;Neurology;Interfaces (computer);Optical
resolving power;Mathematical models;},
Abstract = {In brain-machine interface (BMI) applications, neural firing
activities have been represented by spike counts with a
fixed-width time bin. Adaptive models have been designed to
utilize these bin counts for mapping the associated behavior
which is typically 2D or 3D hand movement. However, the
representation of the firing activities can be enriched by
binning neural spikes with multiple time scales based on
multiresolution analysis. This multiresolution
representation of neural activities can provide more
accurate prediction of the hand movement parameters. Data
mining techniques must be applied to models using
multiresolution representation in order to avoid
overfitting. In this paper, we demonstrate that the
multiresolution representation improves the performance of
the linear model for BMIs compared to the model with the
fixed-width time bin. © 2005 IEEE.},
Key = {06239919050}
}
@article{8473631,
Author = {Sanchez, J.C. and Erdogmus, D. and Nicolelis, M.A.L. and Wessberg, J. and Principe, J.C.},
Title = {Interpreting spatial and temporal neural activity through a
recurrent neural network brain-machine interface},
Journal = {IEEE Trans. Neural Syst. Rehabil. Eng. (USA)},
Volume = {13},
Number = {2},
Pages = {213 - 19},
Year = {2005},
url = {http://dx.doi.org/10.1109/TNSRE.2005.847382},
Keywords = {bioelectric phenomena;biomechanics;brain;handicapped
aids;medical signal processing;neurophysiology;nonlinear
dynamical systems;physiological models;recurrent neural
nets;spatiotemporal phenomena;},
Abstract = {We propose the use of optimized brain-machine interface
(BMI) models for interpreting the spatial and temporal
neural activity generated in motor tasks. In this study, a
nonlinear dynamical neural network is trained to predict the
hand position of primates from neural recordings in a
reaching task paradigm. We first develop a method to reveal
the role attributed by the model to the sampled motor,
premotor, and parietal cortices in generating hand
movements. Next, using the trained model weights, we derive
a temporal sensitivity measure to asses how the model
utilized the sampled cortices and neurons in real-time
during BMI testing},
Key = {8473631}
}
@article{8255493,
Author = {Sanchez, J.C. and Principe, J.C. and Carmena, J.M. and Lebedev, M.A. and Nicolelis, M.A.L.},
Title = {Simultaneus prediction of four kinematic variables for a
brain-machine interface using a single recurrent neural
network},
Journal = {Conference Proceedings. 26th Annual International Conference
of the IEEE Engineering in Medicine and Biology Society
(IEEE Cat. No.04CH37558)},
Volume = {Vol.7},
Pages = {5321 - 4},
Address = {San Francisco, CA, USA},
Year = {2004},
Keywords = {biomechanics;brain;cellular biophysics;kinematics;medical
signal processing;neurophysiology;prosthetics;recurrent
neural nets;user interfaces;},
Abstract = {Implementation of brain-machine interface neural-to-motor
mapping algorithms in low-power, portable digital signal
processors (DSPs) requires efficient use of model resources
especially when predicting signals that show
interdependencies. We show here that a single recurrent
neural network can simultaneously predict hand position and
velocity from the same ensemble of cells using a minimalist
topology. Analysis of the trained topology showed that the
model learns to concurrently represent multiple kinematic
parameters in a single state variable. We further assess the
expressive power of the state variables for both large and
small topologies},
Key = {8255493}
}
@article{04238197985,
Author = {Nicolelis, Miguel A. L. and Birbaumer, Niels and Muller,
Klaus-Robert},
Title = {Special issue on brain-machine interfaces:
Editorial},
Journal = {IEEE Transactions on Biomedical Engineering},
Volume = {51},
Number = {6},
Pages = {877 - 880},
Year = {2004},
url = {http://dx.doi.org/10.1109/TBME.2004.827677},
Key = {04238197985}
}
@article{8044205,
Author = {Krupa, D.J. and Wiest, M.C. and Shuler, M.G. and Laubach, M. and Nicolelis, M.A.L.},
Title = {Layer-specific somatosensory cortical activation during
active tactile discrimination},
Journal = {Science (USA)},
Volume = {304},
Number = {5679},
Pages = {1989 - 92},
Year = {2004},
url = {http://dx.doi.org/10.1126/science.1093318},
Keywords = {neurophysiology;touch (physiological);},
Abstract = {Ensemble neuronal activity was recorded in each layer of the
whisker area of the primary somatosensory cortex (SI) while
rats performed a whisker-dependent tactile discrimination
task. Comparison of this activity with SI activity evoked by
similar passive whisker stimulation revealed fundamental
differences in tactile signal processing during active and
passive stimulation. Moreover, significant layer-specific
functional differences in SI activity were observed during
active discrimination. These differences could not be
explained solely by variations in ascending thalamocortical
input to SI. Instead, these results suggest that top-down
influences during active discrimination may alter the
overall functional nature of SI as well as layer-specific
mechanisms of tactile processing},
Key = {8044205}
}
@article{7981869,
Author = {Bossetti, C.A. and Carmena, J.M. and Nicolelis, M.A.L. and Wolf, P.D.},
Title = {Transmission latencies in a telemetry-linked brain-machine
interface},
Journal = {IEEE Trans. Biomed. Eng. (USA)},
Volume = {51},
Number = {6},
Pages = {919 - 24},
Year = {2004},
url = {http://dx.doi.org/10.1109/TBME.2004.827090},
Keywords = {bioelectric potentials;biomedical telemetry;handicapped
aids;medical computing;neurophysiology;prosthetics;},
Abstract = {To be clinically viable, a brain-machine interface (BMI)
requires transcutaneous telemetry. Spike-based compression
algorithms can be used to reduce the amount of telemetered
data, but this type of system is subject to queuing-based
transmission delays. This paper examines the relationships
between the ratio of output to average input bandwidth of an
implanted device and transmission latency and required queue
depth. The examination was performed with a computer model
designed to simulate the telemetry link. The input to the
model was presorted spike data taken from a macaque monkey
performing a motor task. The model shows that when the
output bandwidth/average input bandwidth is in unity,
significant transmission latencies occur. For a 32-neuron
system, transmitting 50 bytes of data per spike and with an
average neuron firing rate of 8.93 spikes/s, the average
maximum delay was approximately 3.2 s. It is not until the
output bandwidth is four times the average input bandwidth
that average maximum delays are reduced to less than 10 ms.
A comparison of neuron firing rate and resulting latencies
shows that high latencies result from neuron bursting. These
results will impact the design of transcutaneous telemetry
in a BMI},
Key = {7981869}
}
@article{7981871,
Author = {Sanchez, J.C. and Carmena, J.M. and Lebedev, M.A. and Nicolelis, M.A.L. and Harris, J.G. and Principe,
J.C.},
Title = {Ascertaining the importance of neurons to develop better
brain-machine interfaces},
Journal = {IEEE Trans. Biomed. Eng. (USA)},
Volume = {51},
Number = {6},
Pages = {943 - 53},
Year = {2004},
url = {http://dx.doi.org/10.1109/TBME.2004.827061},
Keywords = {bioelectric potentials;biomechanics;cellular
biophysics;correlation methods;handicapped aids;medical
computing;neurophysiology;sensitivity analysis;},
Abstract = {In the design of brain-machine interface (BMI) algorithms,
the activity of hundreds of chronically recorded neurons is
used to reconstruct a variety of kinematic variables. A
significant problem introduced with the use of neural
ensemble inputs for model building is the explosion in the
number of free parameters. Large models not only affect
model generalization but also put a computational burden on
computing an optimal solution especially when the goal is to
implement the BMI in low-power, portable hardware. In this
paper, three methods are presented to quantitatively rate
the importance of neurons in neural to motor mapping, using
single neuron correlation analysis, sensitivity analysis
through a vector linear model, and a model-independent
cellular directional tuning analysis for comparisons
purpose. Although, the rankings are not identical, up to
sixty percent of the top 10 ranking cells were in common.
This set can then be used to determine a reduced-order model
whose performance is similar to that of the ensemble. It is
further shown that by pruning the initial ensemble neural
input with the ranked importance of cells, a reduced sets of
cells (between 40 and 80, depending upon the methods) can be
found that exceed the BMI performance levels of the full
ensemble},
Key = {7981871}
}
@article{8114248,
Author = {Obeid, I. and Nicolelis, M.A.L. and Wolf,
P.D.},
Title = {A multichannel telemetry system for single unit neural
recordings},
Journal = {J. Neurosci. Methods (Netherlands)},
Volume = {133},
Number = {1-2},
Pages = {33 - 8},
Year = {2004},
url = {http://dx.doi.org/10.1016/j.jneumeth.2003.09.023},
Keywords = {bioelectric potentials;biomedical electrodes;biomedical
telemetry;cells (electric);local area networks;medical
signal processing;microcomputers;neurophysiology;signal
sampling;system buses;},
Abstract = {We present the design, testing, and evaluation of a 16
channel wearable telemetry system to facilitate multichannel
single unit recordings from freely moving test subjects. Our
design is comprised of (1) a 16-channel analog front end
board to condition and sample signals derived from implanted
neural electrodes, (2) a digital board for processing and
buffering the digitized waveforms, and (3) an index-card
sized 486 PC equipped with an IEEE 802.11b wireless Ethernet
card. Digitized data (up to 12bits of resolution at 31.25k
samples/s per channel) is transferred to the PC and sent to
a nearby host computer on a wireless local area network. Up
to 12 of the 16 channels were transmitted simultaneously for
sustained periods at a range of 9 m. The device measures 5.1
cm×8.1 cm×12.4 cm, weighs 235 g, and is powered
from rechargeable lithium ion batteries with a lifespan of
45 min at maximum transmission power. The device was
successfully used to record signals from awake, chronically
implanted macaque and owl monkeys},
Key = {8114248}
}
@article{8122917,
Author = {Obeid, I. and Nicolelis, M.A.L. and Wolf,
P.D.},
Title = {A low power multichannel analog front end for portable
neural signal recordings},
Journal = {J. Neurosci. Methods (Netherlands)},
Volume = {133},
Number = {1-2},
Pages = {27 - 32},
Year = {2004},
url = {http://dx.doi.org/10.1016/j.jneumeth.2003.09.024},
Keywords = {analogue-digital conversion;biomedical telemetry;cellular
biophysics;differential amplifiers;high-pass
filters;low-pass filters;medical signal processing;neurophysiology;noise;signal
sampling;time division multiplexing;voltage
regulators;},
Abstract = {We present the design and testing of a 16-channel analog
amplifier for processing neural signals. Each channel has
the following features: (1) variable gain (70-94 dB), (2)
four high pass Bessel filter poles (f<sub>-3 dB</sub>=445
Hz), (3) five low pass Bessel filter poles (f<sub>-3
dB</sub>=6.6 kHz), and (4) differential amplification with a
user selectable reference channel to reject common mode
background biological noise. Processed signals are time
division multiplexed and sampled by an on-board 12-bit
analog to digital converter at up to 62.5k samples/s per
channel. The board is powered by two low dropout voltage
regulators which may be supplied by a single battery. The
board measures 8.1 cm×9.9 cm, weighs 50 g, and
consumes up to 130 mW. Its low input-referred noise (1.0
μ V<sub>RMS</sub>) makes it possible to process low
amplitude neural signals; the board was successfully tested
in vivo to process cortically derived extracellular action
potentials in primates. Signals processed by this board were
compared to those generated by a commercially available
system and were found to be nearly identical. Background
noise generated by mastication was substantially attenuated
by the selectable reference circuit. The described circuit
is light weight and low power and is used as a component of
a wearable multichannel neural telemetry
system},
Key = {8122917}
}
@article{7994145,
Author = {Sanchez, J.C. and Erdogmus, D. and Rao, Y. and Sung-Phil Kim and Nicolelis, M. and Wessberg, J. and Principe,
J.C.},
Title = {Interpreting neural activity through linear and nonlinear
models for brain machine interfaces},
Journal = {Proceedings of the 25th Annual International Conference of
the IEEE Engineering in Medicine and Biology Society (IEEE
Cat. No.03CH37439)},
Volume = {Vol.3},
Pages = {2160 - 3},
Address = {Cancun, Mexico},
Year = {2003},
url = {http://dx.doi.org/10.1109/IEMBS.2003.1280168},
Keywords = {brain;feedforward neural nets;neurophysiology;physiological
models;},
Abstract = {Brain machine interface (BMI) design can be achieved by
training linear and nonlinear models with simultaneously
recorded cortical neural activity and behavior (typically
the hand position of a primate). We propose the use of
optimized BMI models for analyzing neural activity to assess
the role of individual neurons and cortical areas in
generating the performed movement. Two models
(linear-feedforward and nonlinear-feedback) are trained to
predict the hand position of a primate from neural
recordings in a reaching task. Qualitative and quantitative
investigation of the effect of neurons and their
corresponding cortical areas through both models yields
conclusions consistent with neurophysiologic knowledge. In
addition, this analysis revealed the role of these areas and
the importance of the neurons in terms of BMI
design},
Key = {7994145}
}
@article{7797886,
Author = {Sanchez, J.C. and Erdogmus, D. and Rao, Y. and Principe,
J.C. and Nicolelis, M. and Wessberg, J.},
Title = {Learning the contributions of the motor, premotor, and
posterior parietal cortices for hand trajectory
reconstruction in a brain machine interface},
Journal = {Conference Proceedings. 1st International IEEE EMBS
Conference on Neural Engineering 2003 (Cat.
No.03EX606)},
Pages = {59 - 62},
Address = {Capri Island, Italy},
Year = {2003},
url = {http://dx.doi.org/10.1109/CNE.2003.1196755},
Keywords = {multilayer perceptrons;recurrent neural nets;signal
processing;user interfaces;},
Abstract = {The ability to record, in real-time, the activity of
hundreds of cortical neurons gives the ability to
selectively study the function of clusters of cortical
neurons in Brain Machine Interface (BMI) experiments. We
have demonstrated using a recursive multilayer perceptron
(RMLP) that using the appropriate signal processing theory
in a well-chosen parsimonious model, we can develop
constructs that agree with basic physiological modeling of
neural control. By looking through the trained model, we
have found interesting relationships between the neuronal
firing and the movement. The RMLP allows us to continuously
study the relationship between neural activity and behavior
without the active interference of the experimenter. The
findings presented in this study offer an opportunity for
the neuroscience community to compare the cortical
interactions as constructed by the RMLP to what is known
about motor neurophysiology},
Key = {7797886}
}
@article{7838731,
Author = {Sung-Phil Kim and Sanchez, J.C. and Erdogmus, D. and Rao,
Y.N. and Principe, J.C. and Nicolelis, M.},
Title = {Modeling the relation from motor cortical neuronal firing to
hand movements using competitive linear filters and a
MLP},
Journal = {Proceedings of the International Joint Conference on Neural
Networks 2003 (Cat.No.03CH37464)},
Volume = {vol.1},
Pages = {66 - 70},
Address = {Portland, OR, USA},
Year = {2003},
url = {http://dx.doi.org/10.1109/IJCNN.2003.1223293},
Keywords = {biomechanics;brain models;handicapped aids;multilayer
perceptrons;neuromuscular stimulation;position
control;Wiener filters;},
Abstract = {Recent research has demonstrated that linear model are able
to estimate hand positions using populations of action
potentials collected in the pre-motor and motor cortical
areas of a primate's brain. One of the applications of this
result is to restore movement in patients suffering from
paralysis. To implement this technology in real-time,
reliable and accurate signal processing models that produce
sufficient small error in the estimated hand positions are
required. In this paper, we propose the hybrid model
approach that combines competitive linear filters with a
neural network. The mapping performance of our approach is
compared with a single Wiener filter during reaching
movements. Our approach demonstrates more accurate
estimations},
Key = {7838731}
}
@article{7907118,
Author = {Darmanjian, S. and Sung Phil Kim and Nechyba, M.C. and Morrison, S. and Principe, J. and Wessberg, J. and Nicolelis, M.A.L.},
Title = {Bimodal brain-machine interface for motor control of robotic
prosthetic},
Journal = {Proceedings 2003 IEEE/RSJ International Conference on
Intelligent Robots and Systems (IROS 2003) (Cat.
No.03CH37453)},
Volume = {vol.3},
Pages = {3612 - 17},
Address = {Las Vegas, NV, USA},
Year = {2003},
url = {http://dx.doi.org/10.1109/IROS.2003.1249716},
Keywords = {biocontrol;bioelectric potentials;hidden Markov
models;medical robotics;neural nets;neurophysiology;prosthetics;user
interfaces;},
Abstract = {We are working on mapping multi-channel neural spike data,
recorded from multiple cortical areas of an owl monkey, to
corresponding 3D monkey arm positions. In earlier work on
this mapping task, we observed that continuous function
approximators (such as artificial neural networks) have
difficulty in jointly estimating 3D arm positions for two
distinct cases-namely, when the monkey's arm is stationary
and when it is moving. Therefore, we propose a
multiple-model approach that first classifies neural spike
data into two classes, corresponding to two states of the
monkey's arm: (1) stationary and (2) moving. Then, the
output of this classifier is used as a gating mechanism for
subsequent continuous models, with one model per class. In
this paper, we first motivate and discuss our approach.
Next, we present encouraging results for the classifier
stage, based on hidden Markov models (HMMs), and also for
the entire bimodal mapping system. Finally, we conclude with
a discussion of the results and suggest future avenues of
research},
Key = {7907118}
}
@article{7843967,
Author = {Sung-Phil Kim and Sanchez, J.C. and Erdogmus, D. and Rao,
Y.N. and Wessberg, J. and Principe, J.C. and Nicolelis,
M.},
Title = {Divide-and-conquer approach for brain machine interfaces:
nonlinear mixture of competitive linear models},
Journal = {Neural Netw. (UK)},
Volume = {16},
Number = {5-6},
Pages = {865 - 71},
Year = {2003},
url = {http://dx.doi.org/10.1016/S0893-6080(03)00108-4},
Keywords = {brain models;delays;divide and conquer methods;learning
(artificial intelligence);least mean squares
methods;man-machine systems;multilayer perceptrons;nonlinear
network analysis;user interfaces;},
Abstract = {This paper proposes a divide-and-conquer strategy for
designing brain machine interfaces. A nonlinear combination
of competitively trained local linear models (experts) is
used to identify the mapping from neuronal activity in
cortical areas associated with arm movement to the hand
position of a primate. The proposed architecture and the
training algorithm are described in detail and numerical
performance comparisons with alternative linear and
nonlinear modeling approaches, including time-delay neural
networks and recursive multilayer perceptrons, are
presented. This new strategy allows training the local
linear models using normalized LMS and using a relatively
smaller nonlinear network to efficiently combine the
predictions of the linear experts. This leads to savings in
computational requirements, while the performance is still
similar to a large fully nonlinear network},
Key = {7843967}
}
@article{7550839,
Author = {Obeid, I. and Morizio, J.C. and Moxon, K.A. and Nicolelis,
M.A.L. and Wolf, P.D.},
Title = {Two multichannel integrated circuits for neural recording
and signal processing},
Journal = {IEEE Trans. Biomed. Eng. (USA)},
Volume = {50},
Number = {2},
Pages = {255 - 8},
Year = {2003},
url = {http://dx.doi.org/10.1109/TBME.2002.807643},
Keywords = {amplifiers;arrays;biomedical electrodes;biomedical
electronics;CMOS analogue integrated circuits;high-pass
filters;medical signal processing;neurophysiology;prosthetics;somatosensory
phenomena;},
Abstract = {We have developed, manufactured, and tested two analog CMOS
integrated circuit "neurochips" for recording from arrays of
densely packed neural electrodes. Device A is a 16-channel
buffer consisting of parallel noninverting amplifiers with a
gain of 2 V/V. Device B is a 16-channel two-stage analog
signal processor with differential amplification and
high-pass filtering. It features selectable gains of 250 and
500 V/V as well as reference channel selection. The
resulting amplifiers on Device A had a mean gain of 1.99 V/V
with an equivalent input noise of 10 μV<sub>rms</sub>.
Those on Device B had mean gains of 53.4 and 47.4 dB with a
high-pass filter pole at 211 Hz and an equivalent input
noise of 4.4 μV<sub>rms</sub>. Both devices were tested
in vivo with electrode arrays implanted in the somatosensory
cortex},
Key = {7550839}
}
@article{7507580,
Author = {Nicolelis, M.A.L. and Chapin, J.K.},
Title = {Controlling robots with the mind},
Journal = {Sci. Am. (Int. Ed.) (USA)},
Volume = {287},
Number = {4},
Pages = {24 - 31},
Year = {2002},
Keywords = {manipulator dynamics;neurophysiology;robot
dynamics;},
Abstract = {People with nerve or limb injuries may one day be able to
command wheelchairs, prosthetics and even paralyzed arms and
legs by "thinking them through" the motions},
Key = {7507580}
}
@article{7748470,
Author = {Won, D.S. and Obeid, L. and Morizio, J.C. and Nicolelis,
M.A.L. and Wolf, P.D.},
Title = {A multichannel CMOS analog front end IC for neural
recordings},
Journal = {Conference Proceedings. Second Joint EMBS-BMES Conference
2002. 24th Annual International Conference of the
Engineering in Medicine and Biology Society. Annual Fall
Meeting of the Biomedical Engineering Society (Cat.
No.02CH37392)},
Volume = {vol.3},
Pages = {2070 - 1},
Address = {Houston, TX, USA},
Year = {2002},
url = {http://dx.doi.org/10.1109/IEMBS.2002.1053172},
Keywords = {bioelectric potentials;CMOS analogue integrated
circuits;high-pass filters;low-pass filters;neurophysiology;prosthetics;},
Abstract = {A multichannel integrated circuit for processing
extracellular neural signals has been designed and
manufactured. The analog CMOS IC consists of 17 parallel
channels, each comprised of three cascaded stages: bandpass
filter with gain, switched capacitor filters, and output
buffer with selectable gain. The bandpass filter stage
features an opamp with non-inverting resistor feedback and
an off-chip capacitor in the feedback pathway to provide
gain (43 dB) and one high pass filter pole (220 Hz). The low
pass pole is set by the gain-bandwidth product of the opamp.
In the switched capacitor filter stage, a one-pole high pass
filter (500 Hz) cascades into a two-pole biquadratic low
pass filter (5 kHz). The switched capacitor filters may be
controlled by either an onboard tunable ring oscillator
centered at 50 kHz or an off-chip clock. A four-phase clock
splitter provides the necessary filter control-signals; a
phase delay of 180° between the high and low pass clock
lines maximizes settling time between the filters. The
output buffer stage provides selectable gain at 20 dB or 32
dB. The IC was manufactured by AMI using a 0.5 μm triple
metal double poly process, and measures 4.2 × 3.8 mm.
The die is designed to be packaged in a flip-chip
sub-assembly},
Key = {7748470}
}
@article{02477219204,
Author = {Nicolelis, Miguel A.L. and Chapin, John K.},
Title = {Controlling Roberts with the mind},
Journal = {Scientific American},
Volume = {287},
Number = {4},
Pages = {46 -},
Year = {2002},
Key = {02477219204}
}
@article{7535443,
Author = {Sanchez, J.C. and Sung-Phil Kim and Erdogmus, D. and Rao,
Y.N. and Principe, J.C. and Wessberg, J. and Nicolelis,
M.},
Title = {Input-output mapping performance of linear and nonlinear
models for estimating hand trajectories from cortical
neuronal firing patterns},
Journal = {Neural Networks for Signal Processing XII. Proceedings of
the 2002 IEEE Signal Processing Society Workshop. (Cat.
No.02TH8641)},
Pages = {139 - 48},
Address = {Martigny, Switzerland},
Year = {2002},
url = {http://dx.doi.org/10.1109/NNSP.2002.1030025},
Keywords = {brain models;FIR filters;handicapped aids;medical signal
processing;patient treatment;position control;real-time
systems;recurrent neural nets;},
Abstract = {Linear and nonlinear (TDNN) models have been shown to
estimate hand position using populations of action
potentials collected in the pre-motor and motor cortical
areas of a primate's brain. One of the applications of this
discovery is to restore movement in patients suffering from
paralysis. For real-time implementation of this technology,
reliable and accurate signal processing models that produce
small error variance in the estimated positions are
required. In this paper, we compare the mapping performance
of the FIR filter, gamma filter and recurrent neural network
(RNN) in the peaks of reaching movements. Each approach has
strengths and weaknesses that are compared experimentally.
The RNN approach shows very accurate peak position
estimations with small error variance},
Key = {7535443}
}
@article{02307034262,
Author = {Hugh, G.S. and Laubach, M. and Nicolelis, M.A.L. and Henriquez, C.S.},
Title = {A simulator for the analysis of neuronal ensemble activity:
Application to reaching tasks},
Journal = {Neurocomputing},
Volume = {44-46},
Pages = {847 - 854},
Year = {2002},
url = {http://dx.doi.org/10.1016/S0925-2312(02)00482-4},
Keywords = {Learning systems;Muscle;Mathematical models;Computer
simulation;},
Abstract = {A biologically based, multi-cortical computational model was
developed to investigate how ensembles of neurons learn to
execute a three-dimensional reaching task. The model
produces outputs of spike trains that can be analyzed using
a variety of multivariate analysis tools. Simulations show
that after learning, the model neurons exhibit broad
directional tuning that depend on the defined muscle
directions of the simulated arm, and that these neurons form
functional clusters within cortical areas. The utility of
the model is demonstrated by testing arm movement prediction
strategies using ensemble activity. © 2002 Published by
Elsevier Science B.V.},
Key = {02307034262}
}
@article{02487243203,
Author = {Nicolelis, Miguel A.L.},
Title = {The amazing adventures of robotrat},
Journal = {Trends in Cognitive Sciences},
Volume = {6},
Number = {11},
Pages = {449 - 450},
Year = {2002},
url = {http://dx.doi.org/10.1016/S1364-6613(02)01991-5},
Keywords = {Brain;Neurophysiology;},
Abstract = {By using electrical brain stimulation to deliver both
'virtual' tactile cues and rewards to freely roaming rats,
Talwar et al. have been able to instruct animals remotely to
navigate through complex mazes and natural environments they
have never visited before. These results provide both an
elegant alternative way to train animals and a new approach
to study basic neurophysiological principles of animal
navigation.},
Key = {02487243203}
}
@article{7401953,
Author = {Hugh, G.S. and Laubach, M. and Nicolelis, M.A.L. and Henriquez, C.S.},
Title = {A simulator for the analysis of neuronal ensemble activity:
application to reaching tasks},
Journal = {Neurocomputing (Netherlands)},
Volume = {44-46},
Pages = {847 - 54},
Address = {Monterey, CA, USA},
Year = {2002},
Keywords = {bioelectric potentials;brain models;neural
nets;neuromuscular stimulation;},
Abstract = {A biologically based, multi-cortical computational model was
developed to investigate how ensembles of neurons learn to
execute a three-dimensional reaching task. The model
produces outputs of spike trains that can be analyzed using
a variety of multivariate analysis tools. Simulations show
that after learning, the model neurons exhibit broad
directional tuning that depend on the defined muscle
directions of the simulated arm, and that these neurons form
functional clusters within cortical areas. The utility of
the model is demonstrated by testing arm movement prediction
strategies using ensemble activity},
Key = {7401953}
}
@article{6897270,
Author = {Krupa, D.J. and Brisben, A.J. and Nicolelis,
M.A.L.},
Title = {A multi-channel whisker stimulator for producing
spatiotemporally complex tactile stimuli},
Journal = {J. Neurosci. Methods (Netherlands)},
Volume = {104},
Number = {2},
Pages = {199 - 208},
Year = {2001},
url = {http://dx.doi.org/10.1016/S0165-0270(00)00345-9},
Keywords = {biological techniques;neurophysiology;touch
(physiological);},
Abstract = {A system is described that delivers complex, biologically
realistic, tactile stimuli to the rat's facial whisker pad
by independently stimulating up to 16 individual facial
whiskers in a flexible yet highly controlled and repeatable
manner. The system is technically simple and inexpensive to
construct. The system consists of an array of 16
miniature-solenoid driven actuators that are attached to 16
individual facial whiskers via very small (130 μm dia.)
Teflon-coated stainless steel wires. When individual
solenoids are energized, the wire is rapidly retracted,
resulting in a deflection of individual whiskers. The rise
time of deflection is approx. 1 mm/ms. Repeatable
stimulation of individual whiskers can be achieved without
touching adjacent whiskers, thereby allowing a very high
density of stimulators to be attached within the spatially
restricted region of the facial whisker pad. Complex
patterns of whisker stimulation (designed to mimic
biologically realistic stimuli) are delivered to the whisker
pad by activating individual solenoid actuators in precisely
controlled temporal patterns. These stimulations can be
combined with multi-electrode single-unit ensemble
recordings at multiple sites within the rat trigeminal
somatosensory system. Analysis of neuronal population
responses to these complex stimuli is intended to examine
how the trigeminal somatosensory system encodes and
processes spatiotemporally complex stimuli},
Key = {6897270}
}
@article{6633289,
Author = {Laubach, W. and Wessberg, J. and Nicolelis,
M.A.L.},
Title = {Cortical ensemble activity increasingly predicts behaviour
outcomes during learning of a motor task},
Journal = {Nature (UK)},
Volume = {405},
Number = {6786},
Pages = {567 - 71},
Year = {2000},
url = {http://dx.doi.org/10.1038/35014604},
Keywords = {bioelectric potentials;biomechanics;brain;neurophysiology;},
Abstract = {When an animal learns to make movements different stimuli,
changes in activity in the motor cortex seem to accompany
and underlie this learning. The precise nature of
modifications in cortical motor areas during the initial
stages of motor learning, however, is largely unknown. Here,
the authors address this issue by chronically recording from
neuronal ensembles located in the rat motor cortex,
throughout the period required for rats to learn a
reaction-time task. Motor learning was demonstrated by a
decrease in the variance of the rats' reaction times and an
increase in the time the animals were able to wait for a
trigger stimulus. These behavioural changes were correlated
with a significant increase in the authors' ability to
predict the correct or incorrect outcome of single trials
based on 3 measures of neuronal ensemble activity: average
firing rate, temporal patterns of firing, and correlated
firing. This increase in prediction indicates that an
association between sensory cues and movement},
Key = {6633289}
}
@article{6540993,
Author = {Laubach, M. and Shuler, M. and Nicolelis,
M.L.},
Title = {Independent component analyses for quantifying neuronal
ensemble interactions},
Journal = {J. Neurosci. Methods (Netherlands)},
Volume = {94},
Number = {1},
Pages = {141 - 54},
Year = {1999},
url = {http://dx.doi.org/10.1016/S0165-0270(99)00131-4},
Keywords = {neurophysiology;principal component analysis;},
Abstract = {The goal of this study was to compare how multivariate
statistical methods for dimension reduction account for
correlations between simultaneously recorded neurons. Here,
the authors describe applications of principal component
analysis (PCA) and independent component analysis (ICA)
(Cardoso, J.-F., Souloumiac, A. IEE-Proc. F 1993; 140:
362-70; Hyvarinen, A., Oja, E. Neural Comput 1997; 9:
1483-92; Lee, T.W., et al. Neural Comp. 1999; 11: 417-41) to
neuronal ensemble data. Simulated ensembles of neurons were
used to compare how well the methods above could account for
correlated neuronal firing. The simulations showed that
`population vectors' defined by PCA were broadly distributed
over the neuronal ensembles; thus, PCA was unable to
identify independent groupings of neurons that shared common
sources of input. By contrast, the ICA methods were all able
to identify groupings of neurons that emerged due to
correlated firing. This result suggests that correlated
neuronal firing is reflected in higher-order correlations
between neurons and not simply in the neurons' covariance.
To assess the significance of these methods for real
neuronal ensembles, the authors analyzed data from
populations of neurons recorded in the motor cortex of rats
trained to perform a reaction-time task. Scores for PCA and
ICA were reconstructed on a bin-by-bin basis for single
trials. These data were then used to train an artificial
neural network to discriminate between single trials with
either short or long reaction-times. Classifications based
on scores from the ICA-based methods were significantly
better than those based on PCA. For example, scores for
components defined with an ICA-based method, extended ICA
(Lee et al., 1999), classified more trials correctly
(80.58±1.25%) than PCA (73.14±0.84%) for an
ensemble of 26 neurons recorded in the motor cortex (ANOVA:
P<0.005). This result suggests that behaviorally relevant
information is represented in correlated neuronal firing and
can be best detected when higher-order correlations between
neurons are taken into account},
Key = {6540993}
}
@article{6533555,
Author = {Chapin, J.K. and Nicolelis, M.A.L.},
Title = {Principal component analysis of neuronal ensemble activity
reveals multidimensional somatosensory representations},
Journal = {J. Neurosci. Methods (Netherlands)},
Volume = {94},
Number = {1},
Pages = {121 - 40},
Year = {1999},
url = {http://dx.doi.org/10.1016/S0165-0270(99)00130-2},
Keywords = {cellular biophysics;neural nets;neurophysiology;principal
component analysis;somatosensory phenomena;},
Abstract = {Principal components analysis (PCA) was used to define the
linearly dependent factors underlying sensory information
processing in the vibrissal sensory area of the ventral
posterior medial (VPM) thalamus in 8 awake rats. Ensembles
of up to 23 single neurons were simultaneously recorded in
this area, either during long periods of spontaneous
behavior (including exploratory whisking) or controlled
deflection of single whiskers. PCA rotated the matrices of
correlation between these n neurons into a series of n
uncorrelated principal components (PCs), each successive PC
oriented to explain a maximum of the remaining variance. The
fact that this transformation is mathematically equivalent
to the general Hebb algorithm in linear neural networks
provided a major rationale for performing it here on data
from real neuronal ensembles. Typically, most information
correlated across neurons in the ensemble was concentrated
within the first 3-8 PCs. Each of these was found to encode
distinct, and highly significant informational factors.
These factor encodings were assessed in two ways, each
making use of fact that each PC consisted of a matrix of
weightings, one for each neuron. First, the neurons were
rank ordered according to the locations of the central
whiskers in their receptive fields, allowing their
weightings within different PCs to be viewed as a function
of their position within the whisker representation in the
VPM. Each PC was found to define a distinctly different
topographic mapping of the cutaneous surface. Next, the PCs
were used to weight-sum the neurons' simultaneous activities
to create population vectors (PVs). Each PV consisted of a
single continuous time series which represented the
expression of each PC's `magnitude' in response to
stimulation of different whiskers, or during behavioral
events such as active tactile whisking. These showed that
each PC functioned as a feature detector capable of
selectively predicting significant sensory or behavioral
events with far greater statistical reliability than could
any single neuron. The encoding characteristics of the first
few PCs were remarkably consistent across all animals and
experimental conditions, including both spontaneous
exploration and direct sensory stimulation: PC1 positively
weighted all neurons, mainly according to their covariance,
Thus it encoded global magnitude of ensemble activity,
caused either by combined sensory inputs or intrinsic
network activity, such as spontaneous oscillations. PC2
encoded spatial position contrast, generally in the
rostrocaudal dimension, across the whole cutaneous surface
represented by the ensemble. PC3 more selectively encoded
contrast in an orthogonal (usually dorsoventral) dimension.
A variable number of higher numbered PCs encoded local
position contrast within one or more smaller regions of the
cutaneous surface. The remaining PCs typically explained
residual `noise', i.e. the uncorrelated variance that
constituted a major part of each neuron's activity.
Differences in behavioral or sensory experience produced
relatively little in the PC weighting patterns but often
changed the variance they explained (eigenvalues) enough to
alter their ordering. These results argue that PCA provides
a powerful set of tools for selectively measuring neural
ensemble activity within multiple functionally significant
`dimensions' of information processing. As such, it
redefines the `neuron' as an entity which contributes
portions of its variance to processing not one, but several
tasks},
Key = {6533555}
}
@article{97103891001,
Author = {Faggin, B. M. and Nguyen, K. T. and Nicolelis, M. A.
L.},
Title = {Immediate and simultaneous sensory reorganization at
cortical and subcortical levels of the somatosensory
system},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {94},
Number = {17},
Pages = {9428 -},
Year = {1997},
url = {http://dx.doi.org/10.1073/pnas.94.17.9428},
Key = {97103891001}
}
@article{4984702,
Author = {Nicolelis, M.A.L. and Baccala, L.A. and Lin, R.C.S. and Chapin, J.K.},
Title = {Sensorimotor encoding by synchronous neural ensemble
activity at multiple levels of the somatosensory
system},
Journal = {Science (USA)},
Volume = {268},
Number = {5215},
Pages = {1353 - 8},
Year = {1995},
Keywords = {brain;mechanoception;neurophysiology;},
Abstract = {Neural ensemble processing of sensorimotor information
during behavior was investigated by simultaneously recording
up to 48 single neurons at multiple relays of the rat
trigeminal somatosensory system. Cortical, thalamic, and
brainstem neurons exhibited widespread 7- to 10-hertz
synchronous oscillations, which began during attentive
immobility and reliably predicted the imminent onset of
rhythmic whisker twitching. Each oscillatory cycle began as
a traveling wave of neural activity in the cortex that then
spread to the thalamus. Just before the onset of rhythmic
whisker twitching, the oscillations spread to the spinal
trigeminal brainstem complex. Thereafter, the oscillations
at all levels were synchronous with whisker protraction.
Neural structures manifesting these rhythms also exhibited
distributed spatiotemporal patterns of neuronal ensemble
activity in response to tactile stimulation. Thus,
multilevel synchronous activity in this system may encode
not only sensory information but also the onset and temporal
domain of tactile exploratory movements},
Key = {4984702}
}
@article{93051588763,
Author = {Nicolelis, M.A.L. and Lin, R.C.S. and Woodward, D.J. and Chapin, J.K.},
Title = {Induction of immediate spatiotemporal changes in thalamic
networks by peripheral block of ascending cutaneous
information},
Journal = {Nature},
Volume = {361},
Number = {6412},
Pages = {533 -},
Year = {1993},
url = {http://dx.doi.org/10.1038/361533a0},
Key = {93051588763}
}
@article{91041073877,
Author = {Sabin, A.B. and Beckwith, J. and Poritz, M.A. and Bernstein,
H.D. and Walter, P. and Hardin, G. and Meier, P. and Hart,
H. and Lin, C.-S. and Nicolelis, M.A.L. and Schneider, J.S. and Chapin, J.K. Jr.},
Title = {Effectiveness of AIDS vaccines. 'Sequence-Gazing?'. Unus
triginta et quoque anno?. Steroid therapy publication delay.
Buckyballs and double bonds. GABAergic pathway from zona
incerta to neocortex. Clarification},
Journal = {Science},
Volume = {251},
Number = {4998},
Pages = {1161 -},
Year = {1991},
Key = {91041073877}
}
@article{3878412,
Author = {Baccala, L.A. and Nicolelis, M.A.L. and Chai-Hong Yu and Oshiro, M.},
Title = {Structural analysis of neural circuits using the theory of
directed graphs},
Journal = {Comput. Biomed. Res. (USA)},
Volume = {24},
Number = {1},
Pages = {7 - 28},
Year = {1991},
url = {http://dx.doi.org/10.1016/0010-4809(91)90010-T},
Keywords = {directed graphs;neural nets;},
Abstract = {A new approach to analysis of structural properties of
biological neural circuits is proposed based on their
representation in the form of abstract structures called
directed graphs. To exemplify this methodology, structural
properties of a biological neural network and randomly wired
circuits (RC) were compared. The analyzed biological circuit
(BC) represented a sample of 39 neural nuclei which are
responsible for the control of the cardiovascular function
in higher vertebrates. Initially, direct connections of both
circuits were stored in a square matrix format. Then,
standard algorithms derived from the theory of directed
graphs were applied to analyze the pathways of the circuits
according to their length (in number of synapses), degree of
connectedness, and structural strength. Thus, the BC was
characterized by the presence of short, reciprocal, and
unidirectional pathways which presented a high degree of
heterogeneity in their strengths. This heterogeneity was
mainly due to the existence of a small cluster of
reciprocally connected neural nuclei in the circuit that
have access, through short pathways, to most of the
network},
Key = {3878412}
}
@article{3835485,
Author = {Nicolelis, M.A.L. and Chia-Hong Yu and Baccala,
L.A.},
Title = {Structural characterization of the neural circuit
responsible for control of cardiovascular functions in
higher vertebrates},
Journal = {Comput. Biol. Med. (UK)},
Volume = {20},
Number = {6},
Pages = {379 - 400},
Year = {1990},
url = {http://dx.doi.org/10.1016/0010-4825(90)90019-L},
Keywords = {cardiology;neural nets;neurophysiology;zoology;},
Abstract = {A comparison of structural properties of a biological neural
system responsible for cardiovascular function control in
higher vertebrates with randomly connected networks was
pursued using matrix representations of those circuits. The
biological circuit was characterized by the presence of some
heavily connected nuclei in contrast to the random networks
that had equally distributed connections between their
elements. This property of the analysed biological circuit
was shown to account for a high logarithmic correlation
found between two indexes defined to represent pointwise
features of the nuclei and their global contribution to the
whole network. The first index is obtained by the product of
the number of inputs and of outputs of a nucleus and was
called the power index (PI). The second one, called the
occurrence index (OI), defines how many times a specific
nucleus is crossed when all possible pathways joining two
nuclei of the circuit are obtained. This PI-OI correlation
was clearly dependent on the pathway length distribution
(expressed in number of synapses), and was maximal
considering pathways with a low number of synapses. When
randomly connected circuits were analysed, lower correlation
was found between the same two indexes and only for much
longer pathways. Therefore, it is proposed that the analysis
of the PI-OI correlation can be useful to quantify
structural differences between biological neural circuits as
distinguished from randomly connected networks and also
between neural systems at different levels of phylogenetic
and ontogenetic development},
Key = {3835485}
}
@article{3616675,
Author = {Nicolelis, M.A.L. and Tinone, G. and Sameshima, K. and Timo-Iaria, C. and Yu Chia Hong and Van de Bilt,
M.T.},
Title = {Connection, a microcomputer program for storing and
analyzing structural properties of neural
circuits},
Journal = {Comput. Biomed. Res. (USA)},
Volume = {23},
Number = {1},
Pages = {64 - 81},
Year = {1990},
url = {http://dx.doi.org/10.1016/0010-4809(90)90007-Y},
Keywords = {biology computing;medical diagnostic computing;microcomputer
applications;neurophysiology;},
Abstract = {The application of a microcomputer-based system (the
Connection system) designed to deal with neuroanatomical
information commonly analyzed by researchers and involved in
the study of structural properties of neural circuits is
presented. This system can be employed at first as a
readily-accessible database containing physiological and
anatomical data from nuclei of the central nervous system
which define a network with up to 45 elements and their
subdivisions and connections. Once the database from a
specific network is built and stored in a file, routines of
this system can be used to classify the nuclei in terms of
their afferents and efferents and also to display all
possible pathways linking any pair of nuclei and their
respective length (number of synapses). The role of such a
system as an auxiliary tool in neuroanatomical and
electrophysiological research is discussed by presenting the
results obtained from the analysis of the neural circuits
involved in cardiovascular function control in higher
vertebrates},
Key = {3616675}
}
@article{3706431,
Author = {Yu Chia-Hong and Baccala, L.A. and Nicolelis,
M.A.},
Title = {Applying graph theory on a neural network responsible for
the cardiovascular function control: a correlation between
structural properties and physiological functions},
Journal = {MEDINFO 89. Proceedings of the Sixth Conference on Medical
Informatics},
Pages = {87 - 91},
Address = {Beijing, China and Singapore},
Year = {1989},
Keywords = {cardiology;graph theory;neural nets;neurophysiology;},
Abstract = {A neural network responsible for the cardiovascular function
control in high vertebrates represented by 40 neural nuclei
and 162 direct connections between them, was analyzed by
means of graph theory procedures. This quantitative
structural analysis proved useful in forecasting the
physiological role of each nucleus in the overall control
process. New graph procedures were introduced, combining
both pointwise and distributed features of the network and
were successful in highlighting a set of neural nodes that
play a crucial physiological role in maintaining blood
pressure, heart rate and vasomotor tone},
Key = {3706431}
}
@article{90096090667,
Author = {Baccala, Luiz Antonio and Nicolelis, Miguel
A.L.},
Title = {Using computers to survey the epidemiological, environmental
and genetic factors involved in the process of bacteria
resistance acquisition},
Journal = {Proceedings - Annual Symposium on Computer Applications in
Medical Care},
Pages = {261 - 265},
Address = {Washington, DC, USA},
Year = {1989},
Keywords = {Statistical Methods--Time Series Analysis;Computer Aided
Analysis--Medical Applications;Genetic Engineering;Information
Theory;Spectrum Analysis;},
Abstract = {The sensitivity behaviors in time of several species (S.
aureus, E. coli, K. pneumoniae, and P. mirabilis in a total
of 16,334 positive cultures collected at the authors'
hospital from July 1981 to December 1986) to amikacin and
gentamicin are shown to be periodic. The implications of
this finding and parameters, both epidemiological and
genetic, that might be of relevance in its understanding are
discussed as being necessary characteristics of a nosocomial
survey-and-control computer system in which time-series
analysis techniques are of central importance.},
Key = {90096090667}
}
@article{3327494,
Author = {Lage, S.G. and Gutierrez, M.A. and Nicolelis, M.A.L. and Furuie, S.S.},
Title = {A bedside computerized system for monitoring and processing
of biological signals in intensive care units},
Journal = {Computers in Cardiology (Cat. No.87CH2544-5)},
Pages = {561 - 4},
Address = {Leuven, Belgium},
Year = {1988},
Keywords = {computerised monitoring;computerised signal
processing;medical computing;patient care;patient
monitoring;},
Abstract = {A description is given of the application of a generic
bedside system, developed using an IBM-PC compatible, with
the aim of getting essential biological signals to perform a
complete cardiovascular function analysis. Six cardiac
patients with critical heart failure impaired by arrhythmia,
infection, pulmonary embolism and myocardial infarction were
monitored through: (a) ECG; (b) VCG; (c) hemodynamic data
(right atrial pressure, pulmonary arterial pressure,
pulmonary wedge pressure, systemic pressure); (d) cardiac
output (thermodilution and thoracic electrical
bioimpedance); (e) <i>dZ</i>/<i>dt</i> of TEB. These signals
were stored and processed to furnish the
electrical-hemodynamic coupling correlation. As a control,
the results of the cardiac output calculated by TEB were
compared to the thermodilution method. The
<i>dZ</i>/<i>dt</i> wave together with the ECG and
hemodynamic signals allowed continuous determination of the
pre-ejection period, ventricular ejection time,
isovolumetric relaxation, time and ventricular filling
period. The system also permitted several devices to be
interfaced to the microcomputer, a better therapeutic
approach for critical patients, as well as providing data
for medical education and research},
Key = {3327494}
}
@article{3305485,
Author = {Gutierrez, M.A. and Furuie, S.S. and Nicolelis, M.A.L. and Lage, S.},
Title = {Developing a multi-purpose microcomputer-based system for
biological signal analysis for cardiovascular
protocols},
Journal = {Computers in Cardiology (Cat. No.87CH2544-5)},
Pages = {505 - 8},
Address = {Leuven, Belgium},
Year = {1988},
Keywords = {cardiology;computerised signal processing;medical diagnostic
computing;microcomputer applications;},
Abstract = {A description is given of the development of a general
microcomputer-based system to perform biological signal
processing concerning clinical and experimental protocols in
cardiology. In intensive care units the software of this
system enabled the clinical staff to acquire several signals
simultaneously (such as cardiac chamber pressures, arterial
pressure, respiratory flow, ECG, and EEG) and to interface
an IBM PC compatible with other devices (for example a
thoracic electrical bioimpedance system) which can furnish
important ventricular stroke volume measurements. On the
other hand, in experimental protocols, where the
relationship between the latter signals with action
potentials from peripheral nerves was investigated, it was
necessary to design a window discriminator (WD) that allowed
the study of point processes related to the neural control
of the cardiovascular system. This WD was connected to the
microcomputer through a parallel interface with minor
modifications. The software was divided into modules. To
evaluate the signals after acquisition several basic
routines are available (smoothing, statistical and spectral
procedures)},
Key = {3305485}
}
@article{89095041155,
Author = {Nicolelis, Miguel A.L. and Yu, Chia-Hong},
Title = {Defining criteria for quantitative analysis of the neural
network responsible for the cardiovascular function control
by means of a microcomputer system},
Journal = {Proceedings - Annual Symposium on Computer Applications in
Medical Care},
Pages = {256 - 260},
Address = {Washington, DC, USA},
Year = {1988},
Keywords = {Computer Software--Medical Applications;Systems Science and
Cybernetics--Neural Nets;Computers, Microcomputer--Medical
Applications;},
Abstract = {Software designed to deal with information from pathways
connecting nuclei of the central nervous system was used to
study the neural network related to the cardiovascular
control in high vertebrates. The 39 most-cited nuclei in the
literature and 123 links between pairs of nuclei were
considered. Four anatomical indexes were tested as
quantitative parameters of the network. The power index,
which is the product of the inputs and outputs of a nucleus,
was the best in selecting a small set of structures of this
network. This set turned to be the major cluster of nuclei
involved in the neural control of the cardiovascular
function as described in the literature. This index was also
an estimator of the nucleus participation in nuclei. These
results suggest a close relationship between anatomical
properties and physiological function of the nuclei involved
in this network.},
Key = {89095041155}
}
@article{3222798,
Author = {Nicolelis, M.A.L. and Yu Chia Hong},
Title = {Applications of a microcomputer-based system in the analysis
of infection data at the emergency units of a large
hospital},
Journal = {Int. J. Bio-Med. Comput. (Netherlands)},
Volume = {22},
Number = {3-4},
Pages = {183 - 98},
Year = {1988},
Keywords = {data analysis;medical administrative data processing;medical
computing;microcomputer applications;surgery;},
Abstract = {After three years of retrospective study in four emergency
units from a large hospital and analysis of 6283 positive
cultures, a microcomputer database system was built to store
information concerning nosocomial infections in order to
help the clinical staff from those units to study the
incidence of 20 bacterial species and their sensitivity
pattern evolutions for 27 antibiotics. This system was
developed as an alternative to the hospital mainframe
computer microbiological reports. It put emphasis on
graphical outputs instead of the coded tables generated by
the bigger system. This orientation and the possibility of
sectorial infection data analysis were responsible for the
general acceptance of the microcomputer-based system by the
clinical staff. As the first practical results, the system
was able to detect a particular increase in the incidence of
Staphylococcus aureus in surgical emergency units as well as
the dissemination of the antimicrobial resistance patterns
of S. aureus and Klebsiella pneumoniae from the surgical
units to the clinical ones. The time evolution behaviour of
Pseudomonas aeruginosa, Escherichia coli and other
nonfermentative Gram negative bacilli was also studied to
complete the analysis of the most pathogenic bacterial
species found in the emergency units},
Key = {3222798}
}
@article{89044190294,
Author = {Gutierrez, M.A. and Furuie, S.S. and Nicolelis, M.A.L. and Lage, S.},
Title = {Developing a multi-purpose microcomputer-based system for
biological signal analysis for cardiovascular
protocols},
Journal = {Computers in Cardiology},
Pages = {505 - 508},
Address = {Louvain-La-Neuve, Belg},
Year = {1987},
Keywords = {COMPUTER AIDED ANALYSIS -- Medical Applications;HOSPITALS --
Intensive Care Units;WAVEFORM ANALYSIS;},
Abstract = {A description is given of the development of a general
microcomputer-based system to perform biological signal
processing concerning clinical and experimental protocols in
cardiology. At intensive care units the software of this
system enabled the clinical staff to acquire several signals
simultaneously, like the cardiac chamber pressures, arterial
pressure, respiratory flow, ECG, and EEC, and to interface
an IBM PC compatible with other devices (like thoracic
electrical bioimpedance) which can furnish important
ventricular stroke volume mesurements. On the other hand, in
experimental protocols, where the relationship between the
latter signals with action potentials from peripherical
nerves was pursued, it was necessary to design a window
discriminator (WD) that allowed the study of point processes
related to the neural control of the cardiovascular system.
This WD was connected to the microcomputer through the
parallel interface which suffered minor modifications. The
software was divided in modules. To evaluate the signals
after acquisition several basic routines are available
(smoothing, statistical and spectral procedures).},
Key = {89044190294}
}
@article{3361609,
Author = {Nicolelis, M.A.L. and Sameshima, K. and Furuie, S.S. and Gutierrez, M.A.},
Title = {Signal processing system to analyze the neural control on
the cardiovascular function},
Journal = {EFMI - European Federation for Medical Informatics Medical
Informatics Europe '87. Proceedings of the Seventh
International Congress},
Pages = {1318 - 22},
Address = {Rome, Italy},
Year = {1987},
Keywords = {biocontrol;cardiology;computerised signal
processing;microcomputer applications;neurophysiology;},
Abstract = {The study of the neural control on the cardiovascular
function involves the analysis of multiple servomechanisms
with different integration levels in the central nervous
system (1). The input branches of these servomechanisms are
represented by several types of sensors distributed around
the cardiovascular system. To observe the patterns of the
sensor activity together with the signals provided by the
result of the servomechanism effector branch action
(hemodynamic and ECG traces) it was necessary to develop a
system which could sample signals in a broad spectral range.
Describes a microcomputer based system to perform this task,
enabling the user to acquire and analyze on the whole the
signals that are related to the cardiovascular control
process. The hardware (PC/XT and LYNX ADC) and software are
briefly described along with experimental
results},
Key = {3361609}
}
@article{89044190309,
Author = {Lage, S.G. and Gutierrez, M.A. and Nicolelis, M.A.L. and Furuie, S.S.},
Title = {Bedside computerized system for monitoring and processing of
biological signals in intensive care units},
Journal = {Computers in Cardiology},
Pages = {561 - 564},
Address = {Louvain-La-Neuve, Belg},
Year = {1987},
Keywords = {BIOMEDICAL ENGINEERING -- Patient Monitoring;SIGNAL
PROCESSING -- Digital Techniques;WAVEFORM ANALYSIS;COMPUTER
AIDED ANALYSIS;},
Abstract = {A description is given of the application of a generic
bedside system, developed using an IBM-PC compatible, with
the aim of getting essential biological signals to perform a
complete cardiovascular function analysis. Six cardiac
patients with critical heart failure impaired by arrhythmia,
infection, pulmonary embolism and myocardial infarction were
monitored through: (a) ECG; (b) VCG; (c) hemodynamic data
(right atrial pressure, pulmonary arterial pressure,
pulmonary wedge pressure, systemic pressure); (d) cardiac
output (thermodilution and thoracic electrical
bioimpedance); (e) dZ/dt of TEB. These signals were stored
and processed to furnish the electrical-hemodynamic coupling
correlation. As a control, the results of the cardiac output
calculated by TEB were compared to the thermodilution
method. The dZ/dt wave together with the ECG and hemodynamic
signals allowed continuous determination of the pre-ejection
period, ventricular ejection time, isovolumetric relaxation,
time and ventricular filling period. The system also
permitted several devices to be interfaced to the
microcomputer, a better therapeutic approach for critical
patients, as well as providing data for medical education
and research.},
Key = {89044190309}
}
@article{2959216,
Author = {Massad, E. and Engel, A.B. and Nicolelis,
M.A.L.},
Title = {A mathematical model for spirometry},
Journal = {Comput. Biomed. Res. (USA)},
Volume = {20},
Number = {2},
Pages = {105 - 12},
Year = {1987},
url = {http://dx.doi.org/10.1016/0010-4809(87)90038-3},
Keywords = {medical computing;microcomputer applications;physiological
models;pneumodynamics;},
Abstract = {A model originally designed to fit population growth data
was investigated to determine whether it could fit
spirometric traces as a function of time in normal and ill
humans and in normal rats, obtained, respectively, by
spirometer and whole-body plethysmography. The model showed
great accuracy when applied to a simple spirometer coupled
with an analog-to-digital converter interfaced with a
personal computer. It also proved to be a good alternative
for the more expensive and less accurate electronic devices,
as derivative systems, and may be an attractive method for
research and/or diagnostic centers},
Key = {2959216}
}
@article{2602199,
Author = {Massad, E. and Furuie, S.S. and de Assis Moura and L., Jr. and Nascimento Saldiva and P.H. and Nicolelis, M.A. and Bohm,
G.M.},
Title = {The use of a personal computer in the pulmonary function
tests of laboratory rats},
Journal = {Methods Inf. Med. (West Germany)},
Volume = {24},
Number = {4},
Pages = {197 - 9},
Year = {1985},
Keywords = {analogue-digital conversion;Apple computers;biology
computing;microcomputer applications;pneumodynamics;},
Abstract = {A system consisting of an 8-bit word microcomputer of the
APPLE line equipped with an analog-to-digital converter,
connected to a physiograph measuring pressures from a whole
body plethysmograph, was used to perform pulmonary tests in
rats. The system proved to be time-saving without loss of
accuracy when compared to manual calculation methods. It
allows measurement repetition during the same experiment,
which is impossible by manual techniques, and permits to
obtain flow/volume relationships without pneumotachographs
or integrator and/or differentiator modules. This approach
may be applied to humans and used by any
physician},
Key = {2602199}
}
@article{7951637,
Author = {Wiest, M.C. and Nicolelis, M.A.L.},
Title = {Behavioral detection of tactile stimuli during 7-12 Hz
cortical oscillations in awake rats},
Journal = {Nat. Neurosci. (USA)},
Volume = {6},
Number = {9},
Pages = {913 - 14},
url = {http://dx.doi.org/10.1038/nn1107},
Keywords = {bioelectric potentials;biological techniques;brain;microelectrodes;neurophysiology;touch
(physiological);},
Abstract = {Prominent 7-12 Hz oscillations in the primary somatosensory
cortex (S1) of awake but immobile rats might represent a
seizure-like state1 in which neuronal burst firing renders
animals unresponsive to incoming tactile stimuli; others
have proposed that these oscillations are analogous to human
μ rhythm. To test whether rats can respond to tactile
stimuli during 7-12 Hz oscillatory activity, we trained
head-immobilized awake animals to indicate whether they
could detect the occurrence of transient whisker deflections
while we recorded local field potentials (LFPs) from
microelectrode arrays implanted bilaterally in the S1
whisker representation area. They responded rapidly and
reliably, suggesting that this brain rhythm represents
normal physiological activity that does not preclude
perception},
Key = {7951637}
}
