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Publications of Marc A. Sommer    :chronological  alphabetical  combined listing:

%% Journal Articles   
@article{fds343771,
   Author = {Yarossi, M and Quivira, F and Dannhauer, M and Sommer, MA and Brooks,
             DH and Erdoǧmuş, D and Tunik, E},
   Title = {An experimental and computational framework for modeling
             multi-muscle responses to transcranial magnetic stimulation
             of the human motor cortex},
   Journal = {International Ieee/Embs Conference on Neural Engineering,
             Ner},
   Volume = {2019-March},
   Pages = {1122-1125},
   Year = {2019},
   Month = {May},
   ISBN = {9781538679210},
   url = {http://dx.doi.org/10.1109/NER.2019.8717159},
   Abstract = {© 2019 IEEE. Current knowledge of coordinated motor control
             of multiple muscles is derived primarily from invasive
             stimulation-recording techniques in animal models. Similar
             studies are not generally feasible in humans, so a modeling
             framework is needed to facilitate knowledge transfer from
             animal studies. We describe such a framework that uses a
             deep neural network model to map finite element simulation
             of transcranial magnetic stimulation induced electric fields
             (E-fields) in motor cortex to recordings of multi-muscle
             activation. Critically, we show that model generalization is
             improved when we incorporate empirically derived
             physiological models for E-field to neuron firing rate and
             low-dimensional control via muscle synergies.},
   Doi = {10.1109/NER.2019.8717159},
   Key = {fds343771}
}

@article{fds338442,
   Author = {Clements, JM and Kopper, R and Zielinski, DJ and Rao, H and Sommer, MA and Kirsch, E and Mainsah, BO and Collins, LM and Appelbaum,
             LG},
   Title = {Neurophysiology of Visual-Motor Learning during a Simulated
             Marksmanship Task in Immersive Virtual Reality},
   Journal = {25th Ieee Conference on Virtual Reality and 3d User
             Interfaces, Vr 2018 Proceedings},
   Pages = {451-458},
   Publisher = {IEEE},
   Year = {2018},
   Month = {August},
   ISBN = {9781538633656},
   url = {http://dx.doi.org/10.1109/VR.2018.8446068},
   Abstract = {© 2018 IEEE. Immersive virtual reality (VR) systems offer
             flexible control of an interactive environment, along with
             precise position and orientation tracking of realistic
             movements. Immersive VR can also be used in conjunction with
             neurophysiological monitoring techniques, such as
             electroencephalography (EEG), to record neural activity as
             users perform complex tasks. As such, the fusion of VR,
             kinematic tracking, and EEG offers a powerful testbed for
             naturalistic neuroscience research. In this study, we
             combine these elements to investigate the cognitive and
             neural mechanisms that underlie motor skill learning during
             a multi-day simulated marksmanship training regimen
             conducted with 20 participants. On each of 3 days,
             participants performed 8 blocks of 60 trials in which a
             simulated clay pigeon was launched from behind a trap house.
             Participants attempted to shoot the moving target with a
             firearm game controller, receiving immediate positional
             feedback and running scores after each shot. Over the course
             of the 3 days that individuals practiced this protocol, shot
             accuracy and precision improved significantly while reaction
             times got significantly faster. Furthermore, results
             demonstrate that more negative EEG amplitudes produced over
             the visual cortices correlate with better shooting
             performance measured by accuracy, reaction times, and
             response times, indicating that early visual system
             plasticity underlies behavioral learning in this task. These
             findings point towards a naturalistic neuroscience approach
             that can be used to identify neural markers of marksmanship
             performance.},
   Doi = {10.1109/VR.2018.8446068},
   Key = {fds338442}
}


%% Book Chapters   
@misc{fds334788,
   Author = {Abzug, ZM and Sommer, MA},
   Title = {Supplementary Eye Fields},
   Booktitle = {Reference Module in Neuroscience and Biobehavioral
             Psychology},
   Publisher = {Elevier},
   Year = {2017},
   ISBN = {9780128093245},
   Abstract = {The supplementary eye fields (SEFs) are located in
             dorsomedial frontal cortex and contribute to high-level
             control of eye movements. Recordings in the SEF reveal
             neural activity related to vision, saccades, and fixations,
             and electrical stimulation in the SEF evokes saccades and
             fixations. Inactivations and lesions of the SEF, however,
             cause minimal oculomotor deficits. The SEF thus processes
             information relevant to eye movements and influences
             critical oculomotor centers but seems unnecessary for
             generating action. Instead, the SEF has overarching, subtle
             functions that include limb-eye coordination, the timing and
             sequencing of actions, learning, monitoring conflict,
             prediction, supervising behavior, value-based decision
             making, and the monitoring of decisions.},
   Key = {fds334788}
}

@misc{fds334802,
   Author = {Sommer, MA and Wurtz, RH},
   Title = {The Dialogue between Cerebral Cortex and Superior
             Colliculus: Multiple Ascending Pathways for Corollary
             Discharge},
   Volume = {TBD},
   Pages = {TBD},
   Booktitle = {The New Visual Neurosciences},
   Publisher = {M I T PRESS},
   Address = {Cambridge, Massachusetts},
   Editor = {Leo M. Chalupa and Jack S. Werner},
   Year = {2014},
   url = {https://dl.dropbox.com/u/27738651/Publications/SommerWurtz-NewVisNeurosci-InPress.pdf},
   Key = {fds334802}
}

@misc{fds334803,
   Author = {Middlebrooks, PG and Abzug, ZM and Sommer, MA},
   Title = {Studying metacognitive processes at the single neuron
             level},
   Pages = {225-244},
   Booktitle = {The Cognitive Neuroscience of Metacognition},
   Publisher = {Springer Berlin Heidelberg},
   Year = {2013},
   Month = {December},
   ISBN = {3642451896},
   url = {http://dx.doi.org/10.1007/978-3-642-45190-4_10},
   Abstract = {© 2014 Springer-Verlag Berlin Heidelberg. All rights
             reserved. Over the past few decades, strides have been made
             toward understanding how higher level cognitive processes
             are mediated by neuronal spiking activity. Neuronal
             correlates of functions such as attention, executive
             control, working memory, decision-making, and reward
             processing have all been elucidated, to an impressive level
             of detail, at the single cell and circuit
             levels.},
   Doi = {10.1007/978-3-642-45190-4_10},
   Key = {fds334803}
}

@misc{fds334824,
   Author = {Sommer, MA},
   Title = {Supplementary eye fields},
   Pages = {635-643},
   Booktitle = {Encyclopedia of Neuroscience},
   Publisher = {Academic Press},
   Address = {Oxford},
   Editor = {Squire, LR},
   Year = {2009},
   ISBN = {978-0-08-045046-9},
   url = {https://dl.dropboxusercontent.com/u/27738651/Publications/Sommer2009-SEFreview-EncyclOfNeurosci.pdf},
   Abstract = {The supplementary eye fields (SEFs) are located in
             dorsomedial frontal cortex and contribute to high-level
             control of eye movements. Recordings in the SEF reveal
             visual-, saccade-, and fixation-related activity, and
             stimulations in the SEF evoke saccades and fixations.
             Inactivations and lesions of the SEF, however, cause minimal
             oculomotor deficits. The SEF thus processes information
             relevant to eye movements and influences critical oculomotor
             centers but seems unnecessary for generating action.
             Instead, the SEF has overarching, subtle functions that
             include representing space in multiple ways, supervising
             behavior, monitoring conflict, prediction, learning,
             planning sequences, and coordination of the limbs and eyes.
             © 2009 Elsevier Ltd All rights reserved.},
   Doi = {10.1016/B978-008045046-9.01122-0},
   Key = {fds334824}
}

@misc{fds334820,
   Author = {Crapse, TB and Sommer, MA},
   Title = {Corollary Discharge},
   Pages = {325-327},
   Booktitle = {Encyclopedia of Perception},
   Publisher = {SAGE Publications},
   Editor = {Goldstein, RB},
   Year = {2009},
   ISBN = {9781412940818},
   Key = {fds334820}
}

@misc{fds334821,
   Author = {Shin, SY and Crapse, TB and Mayo, JP and Sommer, MA},
   Title = {Visuomotor Integration},
   Pages = {4354-4359},
   Booktitle = {Encyclopedia of Neuroscience},
   Publisher = {SPRINGER},
   Editor = {Binder, MD and Hirokawa, N and Windhorst, U},
   Year = {2009},
   ISBN = {978-3-540-23735-8},
   Key = {fds334821}
}

@misc{fds334822,
   Author = {Sommer, MA and Wurtz, RH},
   Title = {Single Neurons and Primate Behavior},
   Pages = {123-139},
   Booktitle = {Methods in Mind},
   Publisher = {M I T PRESS},
   Editor = {Senior, C and Russell, T and Gazzaniga, M},
   Year = {2009},
   ISBN = {9780262513432},
   Key = {fds334822}
}

@misc{fds207861,
   Author = {Wurtz, Robert H. and Sommer, Marc A.},
   Title = {Single Neurons and Primate Behavior},
   Pages = {123-139},
   Booktitle = {Methods in Mind},
   Publisher = {MIT Press},
   Address = {Cambridge, Massachusetts},
   Editor = {Carl Senior and Tamara Russell and Michael S.
             Gazzaniga},
   Year = {2006},
   ISBN = {978-0262195416},
   url = {https://dl.dropbox.com/u/27738651/Publications/WurtzSommer_MethodsInMind2006.pdf},
   Abstract = {Understanding the brain mechanisms mediating cognitive
             behavior requires combining two experimental steps. First,
             the brain must actually be engaged in the cognitive behavior
             under study. Second, the brain activity must be measured
             during this behavior and the recording sufficiently
             described to permit replication of the experiment. There are
             a number of ways of meeting the second prerequisite, many
             discussed elsewhere in this volume; our chapter will address
             one with unsurpassed spatial and temporal resolution: the
             recording of the action potentials of single neurons.
             Recording single neurons in the brain is a mature technique
             that has been used extensively for over a quarter century.
             In outlining the technique requirements and comparing them
             to those of other techniques, we will focus on what has
             become a cornerstone for the study of brain mechanisms
             underlying cognitive behavior: single-neuron recording from
             awake monkeys trained on behavioral tasks. Our description
             and comments are based on our own experience in studying
             awake monkeys; we also provide references on specific
             technical points not addressed in this chapter.},
   Key = {fds207861}
}

@misc{fds207859,
   Author = {Sommer, Marc A. and Wurtz, Robert H.},
   Title = {The Dialogue between Cerebral Cortex and Superior
             Colliculus: Implications for Saccadic Target Selection and
             Corollary Discharge.},
   Volume = {2},
   Pages = {1466-1484},
   Booktitle = {The Visual Neurosciences},
   Publisher = {MIT Press},
   Address = {Cambridge, Massachusetts},
   Editor = {Leo M. Chalupa and Jack S. Werner},
   Year = {2004},
   ISBN = {978-0-262-03308-4},
   url = {https://dl.dropbox.com/u/27738651/Publications/SommerWurtz_TheVisualNeurosciences2004.pdf},
   Key = {fds207859}
}

@misc{fds334846,
   Author = {Wurtz, RH and Basso, MA and Paré, M and Sommer, MA},
   Title = {The Superior Colliculus and the Cognitive Control of
             Movement},
   Pages = {573-587},
   Booktitle = {The New Cognitive Neurosciences},
   Publisher = {M I T PRESS},
   Editor = {Gazzaniga, MS},
   Year = {2000},
   ISBN = {0262071959},
   Key = {fds334846}
}

@misc{fds334859,
   Author = {Smith, MA and Sadler, RH and Sommer, MA},
   Title = {The Macrophage as the Demyelinative Agent: A Role for
             Antimyelin Antibodies},
   Pages = {51-66},
   Booktitle = {Multiple Sclerosis: Current Status of Research and
             Treatment},
   Publisher = {Demos Publications},
   Editor = {Herndon, RM and Seil, FJ},
   Year = {1994},
   ISBN = {0939957280},
   Key = {fds334859}
}


%% Papers Published   
@article{fds343467,
   Author = {Subramanian, D and Alers, A and Sommer, MA},
   Title = {Corollary Discharge for Action and Cognition.},
   Journal = {Biological Psychiatry: Cognitive Neuroscience and
             Neuroimaging},
   Volume = {4},
   Number = {9},
   Pages = {782-790},
   Publisher = {Elsevier BV},
   Year = {2019},
   Month = {September},
   url = {http://dx.doi.org/10.1016/j.bpsc.2019.05.010},
   Abstract = {In motor systems, a copy of the movement command known as
             corollary discharge is broadcast to other regions of the
             brain to warn them of the impending movement. The premise of
             this review is that the concept of corollary discharge may
             generalize in revealing ways to the brain's cognitive
             systems. An oculomotor pathway from the brain stem to
             frontal cortex provides a well-established example of how
             corollary discharge is instantiated for sensorimotor
             processing. Building on causal evidence from inactivation of
             the pathway, we motivate forward models as a tool for
             understanding the contributions of corollary discharge to
             perception and movement. Finally, we extend the definition
             of corollary discharge to account for signals that may be
             used for cognitive forward models of decision making. This
             framework may provide new insights into signals and circuits
             that contribute to sequential decision processes, the
             breakdown of which may account for some symptoms of
             psychiatric disorders.},
   Doi = {10.1016/j.bpsc.2019.05.010},
   Key = {fds343467}
}

@article{fds341566,
   Author = {Toader, AC and Rao, HM and Ryoo, M and Bohlen, MO and Cruger, JS and Oh-Descher, H and Ferrari, S and Egner, T and Beck, J and Sommer,
             MA},
   Title = {Probabilistic inferential decision-making under time
             pressure in rhesus macaques (Macaca mulatta).},
   Journal = {Journal of Comparative Psychology},
   Volume = {133},
   Number = {3},
   Pages = {380-396},
   Year = {2019},
   Month = {August},
   url = {http://dx.doi.org/10.1037/com0000168},
   Abstract = {Decisions often involve the consideration of multiple cues,
             each of which may inform selection on the basis of learned
             probabilities. Our ability to use probabilistic inference
             for decisions is bounded by uncertainty and constraints such
             as time pressure. Previous work showed that when humans
             choose between visual objects in a multiple-cue,
             probabilistic task, they cope with time pressure by
             discounting the least informative cues, an example of
             satisficing or "good enough" decision-making. We tested two
             rhesus macaques (Macaca mulatta) on a similar task to assess
             their capacity for probabilistic inference and satisficing
             in comparison with humans. In each trial, a monkey viewed
             two compound stimuli consisting of four cue dimensions. Each
             dimension (e.g., color) had two possible states (e.g., red
             or blue) with different probabilistic weights. Selecting the
             stimulus with highest total weight yielded higher odds of
             receiving reward. Both monkeys learned the assigned weights
             at high accuracy. Under time pressure, both monkeys were
             less accurate as a result of decreased use of cue
             information. One monkey adopted the same satisficing
             strategy used by humans, ignoring the least informative cue
             dimension. Both monkeys, however, exhibited a strategy not
             reported for humans, a "group-the-best" strategy in which
             the top two cues were used similarly despite their different
             assigned weights. The results validate macaques as an animal
             model of probabilistic decision-making, establishing their
             capacity to discriminate between objects using at least four
             visual dimensions simultaneously. The time pressure data
             suggest caution, however, in using macaques as models of
             human satisficing. (PsycINFO Database Record (c) 2019 APA,
             all rights reserved).},
   Doi = {10.1037/com0000168},
   Key = {fds341566}
}

@article{fds337180,
   Author = {Abzug, ZM and Sommer, MA},
   Title = {Neuronal correlates of serial decision-making in the
             supplementary eye field},
   Journal = {Journal of Neuroscience},
   Volume = {38},
   Number = {33},
   Pages = {7280-7292},
   Publisher = {Society for Neuroscience},
   Year = {2018},
   Month = {August},
   url = {http://dx.doi.org/10.1523/jneurosci.3643-17.2018},
   Abstract = {Human behavior is influenced by serial decision-making: past
             decisions affect choices that set the context for selecting
             future options. A primate brain region that may be involved
             in linking decisions across time is the supplementary eye
             field (SEF), which, in addition to its well-known visual
             responses and saccade-related activity, also signals the
             rules that govern flexible decisions and the outcomes of
             those decisions. Our hypotheses were that SEF neurons encode
             events during serial decision-making and link the sequential
             decisions with sustained activity. We recorded from neurons
             in the SEF of two rhesus monkeys (Macaca mulatta, one male,
             one female) that performed a serial decision-making task.
             The monkeys used saccades to select a rule that had to be
             applied later in the same trial to discriminate between
             visual stimuli. We found, first, that SEF neurons encoded
             the spatial parameters of saccades during rule selection but
             not during visual discrimination, suggesting a malleability
             to their movement-related tuning. Second, SEF activity
             linked the sequential decisions of rule selection and visual
             discrimination, but not continuously. Instead, rule-encoding
             activity appeared in a “just-in-time” manner before the
             visual discrimination. Third, SEF neurons encoded trial
             outcomes both prospectively, before decisions within a
             trial, and retrospectively, across multiple trials. The
             results thus identify neuronal correlates of rule selection
             and application in the SEF, including transient signals that
             link these sequential decisions. Its activity patterns
             suggest that the SEF participates in serial decision-making
             in a contextually-dependent manner as part of a broader
             network.},
   Doi = {10.1523/jneurosci.3643-17.2018},
   Key = {fds337180}
}

@article{fds334784,
   Author = {Caruso, VC and Pages, DS and Sommer, MA and Groh,
             JM},
   Title = {Beyond the labeled line: variation in visual reference
             frames from intraparietal cortex to frontal eye fields and
             the superior colliculus.},
   Journal = {Journal of Neurophysiology},
   Volume = {119},
   Number = {4},
   Pages = {1411-1421},
   Year = {2018},
   Month = {April},
   url = {http://dx.doi.org/10.1152/jn.00584.2017},
   Abstract = {We accurately perceive the visual scene despite moving our
             eyes ~3 times per second, an ability that requires
             incorporation of eye position and retinal information. In
             this study, we assessed how this neural computation unfolds
             across three interconnected structures: frontal eye fields
             (FEF), intraparietal cortex (LIP/MIP), and the superior
             colliculus (SC). Single-unit activity was assessed in
             head-restrained monkeys performing visually guided saccades
             from different initial fixations. As previously shown, the
             receptive fields of most LIP/MIP neurons shifted to novel
             positions on the retina for each eye position, and these
             locations were not clearly related to each other in either
             eye- or head-centered coordinates (defined as hybrid
             coordinates). In contrast, the receptive fields of most SC
             neurons were stable in eye-centered coordinates. In FEF,
             visual signals were intermediate between those patterns:
             around 60% were eye-centered, whereas the remainder showed
             changes in receptive field location, boundaries, or
             responsiveness that rendered the response patterns hybrid or
             occasionally head-centered. These results suggest that FEF
             may act as a transitional step in an evolution of
             coordinates between LIP/MIP and SC. The persistence across
             cortical areas of mixed representations that do not provide
             unequivocal location labels in a consistent reference frame
             has implications for how these representations must be read
             out. NEW & NOTEWORTHY How we perceive the world as stable
             using mobile retinas is poorly understood. We compared the
             stability of visual receptive fields across different
             fixation positions in three visuomotor regions. Irregular
             changes in receptive field position were ubiquitous in
             intraparietal cortex, evident but less common in the frontal
             eye fields, and negligible in the superior colliculus (SC),
             where receptive fields shifted reliably across fixations.
             Only the SC provides a stable labeled-line code for stimuli
             across saccades.},
   Doi = {10.1152/jn.00584.2017},
   Key = {fds334784}
}

@article{fds334786,
   Author = {Abzug, ZM and Sommer, MA},
   Title = {Serial decision-making in monkeys during an oculomotor
             task},
   Journal = {Journal of Experimental Psychology: Animal Learning and
             Cognition},
   Volume = {44},
   Number = {1},
   Pages = {95-102},
   Publisher = {American Psychological Association},
   Year = {2018},
   Month = {January},
   url = {http://dx.doi.org/10.1037/xan0000154},
   Abstract = {Much of everyday behavior involves serial decision-making,
             in which the outcome of one choice affects another. An
             example is setting rules for oneself: choosing a behavioral
             rule guides appropriate choices in the future. How the brain
             links decisions across time is poorly understood. Neural
             mechanisms could be studied in monkeys, as it is known that
             they can select and use behavioral rules, but existing
             psychophysical paradigms are poorly suited for the
             constraints of neurophysiology. Therefore we designed a
             streamlined task that requires sequential, linked decisions,
             and trained two rhesus monkeys (Macaca mulatta) to perform
             it. The task features trial-by-trial consistency, visual
             stimuli, and eye movement responses to optimize it for
             simultaneous electrophysiological inquiry. In the first
             stage of each trial, the monkeys selected a rule or a rule
             was provided to them. In the second stage, they used the
             rule to discriminate between two test stimuli. Our
             hypotheses were that they could use self-selected rules and
             could deliberately select rules based on reinforcement
             history. We found that the monkeys were as proficient at
             using self-selected rules as instructed rules. Their
             preferences for selecting rules correlated with their
             performance in using them, consistent with systematic,
             rather than random, strategies for accomplishing the task.
             The results confirm and extend prior findings on rule
             selection in monkeys and establish a viable, experimentally
             flexible paradigm for studying the neural basis of serial
             decision-making.},
   Doi = {10.1037/xan0000154},
   Key = {fds334786}
}

@article{fds334785,
   Author = {Rao, HM and Khanna, R and Zielinski, DJ and Lu, Y and Clements, JM and Potter, ND and Sommer, MA and Kopper, R and Appelbaum,
             LG},
   Title = {Sensorimotor Learning during a Marksmanship Task in
             Immersive Virtual Reality.},
   Journal = {Frontiers in Psychology},
   Volume = {9},
   Pages = {58},
   Year = {2018},
   url = {http://dx.doi.org/10.3389/fpsyg.2018.00058},
   Abstract = {Sensorimotor learning refers to improvements that occur
             through practice in the performance of sensory-guided motor
             behaviors. Leveraging novel technical capabilities of an
             immersive virtual environment, we probed the component
             kinematic processes that mediate sensorimotor learning.
             Twenty naïve subjects performed a simulated marksmanship
             task modeled after Olympic Trap Shooting standards. We
             measured movement kinematics and shooting performance as
             participants practiced 350 trials while receiving
             trial-by-trial feedback about shooting success.
             Spatiotemporal analysis of motion tracking elucidated the
             ballistic and refinement phases of hand movements. We found
             systematic changes in movement kinematics that accompanied
             improvements in shot accuracy during training, though
             reaction and response times did not change over blocks. In
             particular, we observed longer, slower, and more precise
             ballistic movements that replaced effort spent on
             corrections and refinement. Collectively, these results
             leverage developments in immersive virtual reality
             technology to quantify and compare the kinematics of
             movement during early learning of full-body sensorimotor
             orienting.},
   Doi = {10.3389/fpsyg.2018.00058},
   Key = {fds334785}
}

@article{fds334787,
   Author = {Oh-Descher, H and Beck, JM and Ferrari, S and Sommer, MA and Egner,
             T},
   Title = {Probabilistic inference under time pressure leads to a
             cortical-to-subcortical shift in decision evidence
             integration.},
   Journal = {Neuroimage},
   Volume = {162},
   Pages = {138-150},
   Year = {2017},
   Month = {November},
   url = {http://dx.doi.org/10.1016/j.neuroimage.2017.08.069},
   Abstract = {Real-life decision-making often involves combining multiple
             probabilistic sources of information under finite time and
             cognitive resources. To mitigate these pressures, people
             "satisfice", foregoing a full evaluation of all available
             evidence to focus on a subset of cues that allow for fast
             and "good-enough" decisions. Although this form of
             decision-making likely mediates many of our everyday
             choices, very little is known about the way in which the
             neural encoding of cue information changes when we satisfice
             under time pressure. Here, we combined human functional
             magnetic resonance imaging (fMRI) with a probabilistic
             classification task to characterize neural substrates of
             multi-cue decision-making under low (1500 ms) and high
             (500 ms) time pressure. Using variational Bayesian
             inference, we analyzed participants' choices to track and
             quantify cue usage under each experimental condition, which
             was then applied to model the fMRI data. Under low time
             pressure, participants performed near-optimally,
             appropriately integrating all available cues to guide
             choices. Both cortical (prefrontal and parietal cortex) and
             subcortical (hippocampal and striatal) regions encoded
             individual cue weights, and activity linearly tracked
             trial-by-trial variations in the amount of evidence and
             decision uncertainty. Under increased time pressure,
             participants adaptively shifted to using a satisficing
             strategy by discounting the least informative cue in their
             decision process. This strategic change in decision-making
             was associated with an increased involvement of the
             dopaminergic midbrain, striatum, thalamus, and cerebellum in
             representing and integrating cue values. We conclude that
             satisficing the probabilistic inference process under time
             pressure leads to a cortical-to-subcortical shift in the
             neural drivers of decisions.},
   Doi = {10.1016/j.neuroimage.2017.08.069},
   Key = {fds334787}
}

@article{fds334789,
   Author = {Rao, HM and Mayo, JP and Sommer, MA},
   Title = {Circuits for presaccadic remapping},
   Journal = {Journal of Neurophysiology},
   Volume = {116},
   Number = {6},
   Pages = {2624-2636},
   Year = {2016},
   Month = {December},
   url = {http://dx.doi.org/10.1152/jn.00182.2016},
   Abstract = {Saccadic eye movements rapidly displace the image of the
             world that is projected onto the retinas. In anticipation of
             each saccade, many neurons in the visual system shift their
             receptive fields. This presaccadic change in visual
             sensitivity, known as remapping, was first documented in the
             parietal cortex and has been studied in many other brain
             regions. Remapping requires information about upcoming
             saccades via corollary discharge. Analyses of neurons in a
             corollary discharge pathway that targets the frontal eye
             field (FEF) suggest that remapping may be assembled in the
             FEF’s local microcircuitry. Complementary data from
             reversible inactivation, neural recording, and modeling
             studies provide evidence that remapping contributes to
             transsaccadic continuity of action and perception. Multiple
             forms of remapping have been reported in the FEF and other
             brain areas, however, and questions remain about reasons for
             these differences. In this review of recent progress, we
             identify three hypotheses that may help to guide further
             investigations into the structure and function of circuits
             for remapping.},
   Doi = {10.1152/jn.00182.2016},
   Key = {fds334789}
}

@article{fds334790,
   Author = {Oh, H and Beck, JM and Zhu, P and Sommer, MA and Ferrari, S and Egner,
             T},
   Title = {Satisficing in split-second decision making is characterized
             by strategic cue discounting.},
   Journal = {J Exp Psychol Learn Mem Cogn},
   Volume = {42},
   Number = {12},
   Pages = {1937-1956},
   Year = {2016},
   Month = {December},
   url = {http://dx.doi.org/10.1037/xlm0000284},
   Abstract = {Much of our real-life decision making is bounded by
             uncertain information, limitations in cognitive resources,
             and a lack of time to allocate to the decision process. It
             is thought that humans overcome these limitations through
             satisficing, fast but "good-enough" heuristic decision
             making that prioritizes some sources of information (cues)
             while ignoring others. However, the decision-making
             strategies we adopt under uncertainty and time pressure, for
             example during emergencies that demand split-second choices,
             are presently unknown. To characterize these decision
             strategies quantitatively, the present study examined how
             people solve a novel multicue probabilistic classification
             task under varying time pressure, by tracking shifts in
             decision strategies using variational Bayesian inference. We
             found that under low time pressure, participants correctly
             weighted and integrated all available cues to arrive at
             near-optimal decisions. With increasingly demanding,
             subsecond time pressures, however, participants
             systematically discounted a subset of the cue information by
             dropping the least informative cue(s) from their decision
             making process. Thus, the human cognitive apparatus copes
             with uncertainty and severe time pressure by adopting a
             "drop-the-worst" cue decision making strategy that minimizes
             cognitive time and effort investment while preserving the
             consideration of the most diagnostic cue information, thus
             maintaining "good-enough" accuracy. This advance in our
             understanding of satisficing strategies could form the basis
             of predicting human choices in high time pressure scenarios.
             (PsycINFO Database Record},
   Doi = {10.1037/xlm0000284},
   Key = {fds334790}
}

@article{fds334791,
   Author = {Caruso, VC and Pages, DS and Sommer, MA and Groh,
             JM},
   Title = {Similar prevalence and magnitude of auditory-evoked and
             visually evoked activity in the frontal eye fields:
             implications for multisensory motor control.},
   Journal = {Journal of Neurophysiology},
   Volume = {115},
   Number = {6},
   Pages = {3162-3173},
   Year = {2016},
   Month = {June},
   url = {http://dx.doi.org/10.1152/jn.00935.2015},
   Abstract = {Saccadic eye movements can be elicited by more than one type
             of sensory stimulus. This implies substantial
             transformations of signals originating in different sense
             organs as they reach a common motor output pathway. In this
             study, we compared the prevalence and magnitude of auditory-
             and visually evoked activity in a structure implicated in
             oculomotor processing, the primate frontal eye fields (FEF).
             We recorded from 324 single neurons while 2 monkeys
             performed delayed saccades to visual or auditory targets. We
             found that 64% of FEF neurons were active on presentation of
             auditory targets and 87% were active during auditory-guided
             saccades, compared with 75 and 84% for visual targets and
             saccades. As saccade onset approached, the average level of
             population activity in the FEF became indistinguishable on
             visual and auditory trials. FEF activity was better
             correlated with the movement vector than with the target
             location for both modalities. In summary, the large
             proportion of auditory-responsive neurons in the FEF, the
             similarity between visual and auditory activity levels at
             the time of the saccade, and the strong correlation between
             the activity and the saccade vector suggest that auditory
             signals undergo tailoring to match roughly the strength of
             visual signals present in the FEF, facilitating accessing of
             a common motor output pathway.},
   Doi = {10.1152/jn.00935.2015},
   Key = {fds334791}
}

@article{fds334792,
   Author = {Zielinski, DJ and Sommer, MA and Rao, HM and Appelbaum, LG and Potter,
             ND and Kopper, R},
   Title = {Evaluating the effects of image persistence on dynamic
             target acquisition in low frame rate virtual
             environments},
   Journal = {2016 Ieee Symposium on 3d User Interfaces, 3dui 2016
             Proceedings},
   Pages = {133-140},
   Publisher = {IEEE},
   Year = {2016},
   Month = {April},
   url = {http://dx.doi.org/10.1109/3DUI.2016.7460043},
   Abstract = {© 2016 IEEE. User performance in virtual environments with
             degraded visual conditions due to low frame rates is an
             interesting area of inquiry. Visual content shown in a low
             frame rate simulation has the quality of the original image,
             but persists for an extended period until the next frame is
             displayed (so-called high persistence-HP). An alternative,
             called low persistence (LP), involves displaying the
             rendered frame for a single display frame and blanking the
             screen while waiting for the next frame to be generated.
             Previous research has evaluated the usefulness of the LP
             technique in low frame rate simulations during a static
             target acquisition task. To gain greater knowledge about the
             LP technique, we have conducted a user study to evaluate
             user performance and learning during a dynamic target
             acquisition task. The acquisition task was evaluated under a
             high frame rate, (60 fps) condition, a traditional low frame
             rate HP condition (10 fps), and the experimental low frame
             rate LP technique. The task involved the acquisition of
             targets moving along several different trajectories, modeled
             after a shotgun trap shooting task. The results of our study
             indicate the LP condition approaches high frame rate
             performance within certain classes of target trajectories.
             Interestingly we also see that learning is consistent across
             conditions, indicating that it may not always be necessary
             to train under a visually high frame rate system to learn a
             particular task. We discuss implications of using the LP
             technique to mitigate low frame rate issues as well as its
             potential usefulness for training in low frame rate virtual
             environments.},
   Doi = {10.1109/3DUI.2016.7460043},
   Key = {fds334792}
}

@article{fds334793,
   Author = {Raghavan, RT and Prevosto, V and Sommer, MA},
   Title = {Contribution of cerebellar loops to action
             timing},
   Journal = {Current Opinion in Behavioral Sciences},
   Volume = {8},
   Pages = {28-34},
   Publisher = {Elsevier},
   Year = {2016},
   Month = {March},
   url = {http://dx.doi.org/10.1016/j.cobeha.2016.01.008},
   Abstract = {Recent studies of sensorimotor processing have benefited
             from decision-making paradigms that emphasize the selection
             of appropriate movements. Selecting when to make those
             responses, or action timing, is important as well. Although
             the cerebellum is commonly viewed as a controller of
             movement dynamics, its role in action timing is also firmly
             supported. Several lines of research have now extended this
             idea. Anatomical findings have revealed connections between
             the cerebellum and broader timing circuits,
             neurophysiological results have suggested mechanisms for
             timing within its microcircuitry, and theoretical work has
             indicated how temporal signals are processed through it and
             decoded by its targets. These developments are inspiring
             renewed studies of the role of the cerebellar loops in
             action timing.},
   Doi = {10.1016/j.cobeha.2016.01.008},
   Key = {fds334793}
}

@article{fds334794,
   Author = {Rao, HM and San Juan and J and Shen, FY and Villa, JE and Rafie, KS and Sommer, MA},
   Title = {Neural Network Evidence for the Coupling of Presaccadic
             Visual Remapping to Predictive Eye Position
             Updating.},
   Journal = {Frontiers in Computational Neuroscience},
   Volume = {10},
   Pages = {52},
   Year = {2016},
   Month = {January},
   url = {http://dx.doi.org/10.3389/fncom.2016.00052},
   Abstract = {As we look around a scene, we perceive it as continuous and
             stable even though each saccadic eye movement changes the
             visual input to the retinas. How the brain achieves this
             perceptual stabilization is unknown, but a major hypothesis
             is that it relies on presaccadic remapping, a process in
             which neurons shift their visual sensitivity to a new
             location in the scene just before each saccade. This
             hypothesis is difficult to test in vivo because complete,
             selective inactivation of remapping is currently
             intractable. We tested it in silico with a hierarchical,
             sheet-based neural network model of the visual and
             oculomotor system. The model generated saccadic commands to
             move a video camera abruptly. Visual input from the camera
             and internal copies of the saccadic movement commands, or
             corollary discharge, converged at a map-level simulation of
             the frontal eye field (FEF), a primate brain area known to
             receive such inputs. FEF output was combined with eye
             position signals to yield a suitable coordinate frame for
             guiding arm movements of a robot. Our operational definition
             of perceptual stability was "useful stability," quantified
             as continuously accurate pointing to a visual object despite
             camera saccades. During training, the emergence of useful
             stability was correlated tightly with the emergence of
             presaccadic remapping in the FEF. Remapping depended on
             corollary discharge but its timing was synchronized to the
             updating of eye position. When coupled to predictive eye
             position signals, remapping served to stabilize the target
             representation for continuously accurate pointing. Graded
             inactivations of pathways in the model replicated, and
             helped to interpret, previous in vivo experiments. The
             results support the hypothesis that visual stability
             requires presaccadic remapping, provide explanations for the
             function and timing of remapping, and offer testable
             hypotheses for in vivo studies. We conclude that remapping
             allows for seamless coordinate frame transformations and
             quick actions despite visual afferent lags. With visual
             remapping in place for behavior, it may be exploited for
             perceptual continuity.},
   Doi = {10.3389/fncom.2016.00052},
   Key = {fds334794}
}

@article{fds334795,
   Author = {Rao, HM and Abzug, ZM and Sommer, MA},
   Title = {Visual continuity across saccades is influenced by
             expectations.},
   Journal = {Journal of Vision},
   Volume = {16},
   Number = {5},
   Pages = {7},
   Year = {2016},
   Month = {January},
   url = {http://dx.doi.org/10.1167/16.5.7},
   Abstract = {As we make saccades, the image on each retina is displaced,
             yet our visual perception is uninterrupted. This is commonly
             referred to as transsaccadic perceptual stability, but such
             a description is inadequate. Some visual objects are stable
             (e.g., rocks) and should be perceived as such across
             saccades, but other objects may move at any time (e.g.,
             birds). Stability is probabilistic in natural scenes. Here
             we extend the common notion of transsaccadic visual
             stability to a more general, ecologically based hypothesis
             of transsaccadic visual continuity in which postsaccadic
             percepts of objects depend on expectations about their
             probability of movement. Subjects made a saccade to a target
             and reported whether it seemed displaced after the saccade.
             Targets had varying probabilities of movement (ranging from
             0.1-0.9) that corresponded to their color (spectrum from
             blue to red). Performance was compared before and after
             subjects were told about the color-probability pairings
             ("uninformed" vs. "informed" conditions). Analyses focused
             on signal detection and psychometric threshold measures. We
             found that in the uninformed condition, performance was
             similar across color-probability pairings, but in the
             informed condition, response biases varied with probability
             of movement, and movement-detection sensitivities were
             higher for rarely moving targets. We conclude that subjects
             incorporate priors about object movement into their
             judgments of visual continuity across saccades.},
   Doi = {10.1167/16.5.7},
   Key = {fds334795}
}

@article{fds334796,
   Author = {Mayo, JP and DiTomasso, AR and Sommer, MA and Smith,
             MA},
   Title = {Dynamics of visual receptive fields in the macaque frontal
             eye field.},
   Journal = {Journal of Neurophysiology},
   Volume = {114},
   Number = {6},
   Pages = {3201-3210},
   Year = {2015},
   Month = {December},
   url = {http://dx.doi.org/10.1152/jn.00746.2015},
   Abstract = {Neuronal receptive fields (RFs) provide the foundation for
             understanding systems-level sensory processing. In early
             visual areas, investigators have mapped RFs in detail using
             stochastic stimuli and sophisticated analytical approaches.
             Much less is known about RFs in prefrontal cortex. Visual
             stimuli used for mapping RFs in prefrontal cortex tend to
             cover a small range of spatial and temporal parameters,
             making it difficult to understand their role in visual
             processing. To address these shortcomings, we implemented a
             generalized linear model to measure the RFs of neurons in
             the macaque frontal eye field (FEF) in response to sparse,
             full-field stimuli. Our high-resolution, probabilistic
             approach tracked the evolution of RFs during passive
             fixation, and we validated our results against conventional
             measures. We found that FEF neurons exhibited a surprising
             level of sensitivity to stimuli presented as briefly as 10
             ms or to multiple dots presented simultaneously, suggesting
             that FEF visual responses are more precise than previously
             appreciated. FEF RF spatial structures were largely
             maintained over time and between stimulus conditions. Our
             results demonstrate that the application of probabilistic RF
             mapping to FEF and similar association areas is an important
             tool for clarifying the neuronal mechanisms of
             cognition.},
   Doi = {10.1152/jn.00746.2015},
   Key = {fds334796}
}

@article{fds334797,
   Author = {Grigsby, EM and Koval, MJ and Smith, MV and Mueller, JK and Deng, ZD and Peterchev, A and Grill, WM and Sommer, MA},
   Title = {Neural Effects of rTMS: Single Neuron Recordings From a
             Rhesus Macaque},
   Journal = {The Journal of Ect},
   Volume = {31},
   Number = {3},
   Pages = {E33-E33},
   Publisher = {LIPPINCOTT WILLIAMS & WILKINS},
   Year = {2015},
   Month = {September},
   Key = {fds334797}
}

@article{fds334798,
   Author = {Zielinski, DJ and Rao, HM and Sommer, MA and Kopper,
             R},
   Title = {Exploring the Effects of Image Persistence in Low Frame Rate
             Virtual Environments},
   Journal = {Proceedings of the Ieee Virtual Reality Conference},
   Pages = {19-26},
   Publisher = {IEEE Computer Society},
   Year = {2015},
   url = {http://dx.doi.org/10.1109/vr.2015.7223319},
   Abstract = {© 2015 IEEE. In virtual reality applications, there is an
             aim to provide real time graphics which run at high refresh
             rates. However, there are many situations in which this is
             not possible due to simulation or rendering issues. When
             running at low frame rates, several aspects of the user
             experience are affected. For example, each frame is
             displayed for an extended period of time, causing a high
             persistence image artifact. The effect of this artifact is
             that movement may lose continuity, and the image jumps from
             one frame to another. In this paper, we discuss our initial
             exploration of the effects of high persistence frames caused
             by low refresh rates and compare it to high frame rates and
             to a technique we developed to mitigate the effects of low
             frame rates. In this technique, the low frame rate
             simulation images are displayed with low persistence by
             blanking out the display during the extra time such image
             would be displayed. In order to isolate the visual effects,
             we constructed a simulator for low and high persistence
             displays that does not affect input latency. A controlled
             user study comparing the three conditions for the tasks of
             3D selection and navigation was conducted. Results indicate
             that the low persistence display technique may not
             negatively impact user experience or performance as compared
             to the high persistence case. Directions for future work on
             the use of low persistence displays for low frame rate
             situations are discussed.},
   Doi = {10.1109/vr.2015.7223319},
   Key = {fds334798}
}

@article{fds334799,
   Author = {Matthews, WJ and Terhune, DB and van Rijn, H and Eagleman, DM and Sommer, MA and Meck, WA},
   Title = {Subjective duration as a signature of coding efficiency:
             Emerging links among stimulus repetition, predictive coding,
             and cortical GABA levels},
   Journal = {Timing & Time Perception Reviews},
   Volume = {1},
   Pages = {11 pages},
   Publisher = {Brill Publishers},
   Year = {2014},
   Month = {December},
   Abstract = {Immediate repetition of a stimulus reduces its apparent
             duration relative to a novel item. Recent work indicates
             that this may reflect suppressed cortical responses to
             repeated stimuli, arising from neural adaptation and/or the
             predictive coding of expected stimuli. This article
             summarizes recent behavioral and neurobiological studies
             linking perceived time to the magnitude of cortical
             responses, including work suggesting that variations in
             GABA-mediated cortical inhibition may underlie some of the
             individual differences in time perception. We suggest that
             the firing of cortical neurons can be modified using simple
             recurrent networks with time-dependent processes that are
             modulated by GABA levels. These local networks feed into a
             core-timing network used to integrate across stimulus
             inputs/modalities, thereby allowing for the coordination of
             multiple duration ranges and effector systems.},
   Key = {fds334799}
}

@article{fds334800,
   Author = {Mitchell, AS and Sherman, SM and Sommer, MA and Mair, RG and Vertes, RP and Chudasama, Y},
   Title = {Advances in understanding mechanisms of thalamic relays in
             cognition and behavior.},
   Journal = {The Journal of Neuroscience : the Official Journal of the
             Society for Neuroscience},
   Volume = {34},
   Number = {46},
   Pages = {15340-15346},
   Year = {2014},
   Month = {November},
   url = {http://dx.doi.org/10.1523/JNEUROSCI.3289-14.2014},
   Abstract = {The main impetus for a mini-symposium on corticothalamic
             interrelationships was the recent number of studies
             highlighting the role of the thalamus in aspects of
             cognition beyond sensory processing. The thalamus
             contributes to a range of basic cognitive behaviors that
             include learning and memory, inhibitory control,
             decision-making, and the control of visual orienting
             responses. Its functions are deeply intertwined with those
             of the better studied cortex, although the principles
             governing its coordination with the cortex remain opaque,
             particularly in higher-level aspects of cognition. How
             should the thalamus be viewed in the context of the rest of
             the brain? Although its role extends well beyond relaying of
             sensory information from the periphery, the main function of
             many of its subdivisions does appear to be that of a relay
             station, transmitting neural signals primarily to the
             cerebral cortex from a number of brain areas. In cognition,
             its main contribution may thus be to coordinate signals
             between diverse regions of the telencephalon, including the
             neocortex, hippocampus, amygdala, and striatum. This central
             coordination is further subject to considerable extrinsic
             control, for example, inhibition from the basal ganglia,
             zona incerta, and pretectal regions, and chemical modulation
             from ascending neurotransmitter systems. What follows is a
             brief review on the role of the thalamus in aspects of
             cognition and behavior, focusing on a summary of the topics
             covered in a mini-symposium held at the Society for
             Neuroscience meeting, 2014.},
   Doi = {10.1523/JNEUROSCI.3289-14.2014},
   Key = {fds334800}
}

@article{fds334801,
   Author = {Mueller, JK and Grigsby, EM and Prevosto, V and Petraglia, FW and Rao,
             H and Deng, Z-D and Peterchev, AV and Sommer, MA and Egner, T and Platt,
             ML and Grill, WM},
   Title = {Simultaneous transcranial magnetic stimulation and
             single-neuron recording in alert non-human
             primates.},
   Journal = {Nat Neurosci},
   Volume = {17},
   Number = {8},
   Pages = {1130-1136},
   Year = {2014},
   Month = {August},
   url = {http://dx.doi.org/10.1038/nn.3751},
   Abstract = {Transcranial magnetic stimulation (TMS) is a widely used,
             noninvasive method for stimulating nervous tissue, yet its
             mechanisms of effect are poorly understood. Here we report
             new methods for studying the influence of TMS on single
             neurons in the brain of alert non-human primates. We
             designed a TMS coil that focuses its effect near the tip of
             a recording electrode and recording electronics that enable
             direct acquisition of neuronal signals at the site of peak
             stimulus strength minimally perturbed by stimulation
             artifact in awake monkeys (Macaca mulatta). We recorded
             action potentials within ∼1 ms after 0.4-ms TMS pulses and
             observed changes in activity that differed significantly for
             active stimulation as compared with sham stimulation. This
             methodology is compatible with standard equipment in primate
             laboratories, allowing easy implementation. Application of
             these tools will facilitate the refinement of next
             generation TMS devices, experiments and treatment
             protocols.},
   Doi = {10.1038/nn.3751},
   Key = {fds334801}
}

@article{fds334804,
   Author = {Prevosto, V and Sommer, MA},
   Title = {Cognitive control of movement via the cerebellar-recipient
             thalamus.},
   Journal = {Frontiers in Systems Neuroscience},
   Volume = {7},
   Pages = {56},
   Year = {2013},
   Month = {October},
   url = {http://dx.doi.org/10.3389/fnsys.2013.00056},
   Abstract = {The cognitive control of behavior was long considered to be
             centralized in cerebral cortex. More recently, subcortical
             structures such as cerebellum and basal ganglia have been
             implicated in cognitive functions as well. The fact that
             subcortico-cortical circuits for the control of movement
             involve the thalamus prompts the notion that activity in
             movement-related thalamus may also reflect elements of
             cognitive behavior. Yet this hypothesis has rarely been
             investigated. Using the pathways linking cerebellum to
             cerebral cortex via the thalamus as a template, we review
             evidence that the motor thalamus, together with
             movement-related central thalamus have the requisite
             connectivity and activity to mediate cognitive aspects of
             movement control.},
   Doi = {10.3389/fnsys.2013.00056},
   Key = {fds334804}
}

@article{fds334805,
   Author = {Ashmore, RC and Sommer, MA},
   Title = {Delay activity of saccade-related neurons in the caudal
             dentate nucleus of the macaque cerebellum.},
   Journal = {Journal of Neurophysiology},
   Volume = {109},
   Number = {8},
   Pages = {2129-2144},
   Year = {2013},
   Month = {April},
   ISSN = {0022-3077},
   url = {https://dl.dropboxusercontent.com/u/27738651/Publications/AshmoreSommer2013-CaudalDentateNucleus.pdf},
   Abstract = {The caudal dentate nucleus (DN) in lateral cerebellum is
             connected with two visual/oculomotor areas of the cerebrum:
             the frontal eye field and lateral intraparietal cortex. Many
             neurons in frontal eye field and lateral intraparietal
             cortex produce "delay activity" between stimulus and
             response that correlates with processes such as motor
             planning. Our hypothesis was that caudal DN neurons would
             have prominent delay activity as well. From lesion studies,
             we predicted that this activity would be related to
             self-timing, i.e., the triggering of saccades based on the
             internal monitoring of time. We recorded from neurons in the
             caudal DN of monkeys (Macaca mulatta) that made delayed
             saccades with or without a self-timing requirement. Most
             (84%) of the caudal DN neurons had delay activity. These
             neurons conveyed at least three types of information. First,
             their activity was often correlated, trial by trial, with
             saccade initiation. Correlations were found more frequently
             in a task that required self-timing of saccades (53% of
             neurons) than in a task that did not (27% of neurons).
             Second, the delay activity was often tuned for saccade
             direction (in 65% of neurons). This tuning emerged
             continuously during a trial. Third, the time course of delay
             activity associated with self-timed saccades differed
             significantly from that associated with visually guided
             saccades (in 71% of neurons). A minority of neurons had
             sensory-related activity. None had presaccadic bursts, in
             contrast to DN neurons recorded more rostrally. We conclude
             that caudal DN neurons convey saccade-related delay activity
             that may contribute to the motor preparation of when and
             where to move.},
   Doi = {10.1152/jn.00906.2011},
   Key = {fds334805}
}

@article{fds334806,
   Author = {Smith, MA and Sommer, MA},
   Title = {Spatial and temporal scales of neuronal correlation in
             visual area V4.},
   Journal = {The Journal of Neuroscience : the Official Journal of the
             Society for Neuroscience},
   Volume = {33},
   Number = {12},
   Pages = {5422-5432},
   Year = {2013},
   Month = {March},
   ISSN = {0270-6474},
   url = {https://dl.dropbox.com/u/27738651/Publications/SmithSommer2013-SpatialTemporalCorrelationsV4.pdf},
   Abstract = {The spiking activity of nearby cortical neurons is
             correlated on both short and long time scales. Understanding
             this shared variability in firing patterns is critical for
             appreciating the representation of sensory stimuli in
             ensembles of neurons, the coincident influences of neurons
             on common targets, and the functional implications of
             microcircuitry. Our knowledge about neuronal correlations,
             however, derives largely from experiments that used
             different recording methods, analysis techniques, and
             cortical regions. Here we studied the structure of neuronal
             correlation in area V4 of alert macaques using recording and
             analysis procedures designed to match those used previously
             in primary visual cortex (V1), the major input to V4. We
             found that the spatial and temporal properties of
             correlations in V4 were remarkably similar to those of V1,
             with two notable differences: correlated variability in V4
             was approximately one-third the magnitude of that in V1 and
             synchrony in V4 was less temporally precise than in V1. In
             both areas, spontaneous activity (measured during fixation
             while viewing a blank screen) was approximately twice as
             correlated as visual-evoked activity. The results provide a
             foundation for understanding how the structure of neuronal
             correlation differs among brain regions and stages in
             cortical processing and suggest that it is likely governed
             by features of neuronal circuits that are shared across the
             visual cortex.},
   Doi = {10.1523/JNEUROSCI.4782-12.2013},
   Key = {fds334806}
}

@article{fds334807,
   Author = {Mayo, JP and Sommer, MA},
   Title = {Neuronal correlates of visual time perception at brief
             timescales.},
   Journal = {Proceedings of the National Academy of Sciences of the
             United States of America},
   Volume = {110},
   Number = {4},
   Pages = {1506-1511},
   Year = {2013},
   Month = {January},
   url = {https://dl.dropbox.com/u/27738651/Publications/MayoSommer2013-ReprintIncludingSupplInfo.pdf},
   Abstract = {Successful interaction with the world depends on accurate
             perception of the timing of external events. Neurons at
             early stages of the primate visual system represent
             time-varying stimuli with high precision. However, it is
             unknown whether this temporal fidelity is maintained in the
             prefrontal cortex, where changes in neuronal activity
             generally correlate with changes in perception. One reason
             to suspect that it is not maintained is that humans
             experience surprisingly large fluctuations in the perception
             of time. To investigate the neuronal correlates of time
             perception, we recorded from neurons in the prefrontal
             cortex and midbrain of monkeys performing a
             temporal-discrimination task. Visual time intervals were
             presented at a timescale relevant to natural behavior (<500
             ms). At this brief timescale, neuronal adaptation--time-dependent
             changes in the size of successive responses--occurs. We
             found that visual activity fluctuated with timing judgments
             in the prefrontal cortex but not in comparable midbrain
             areas. Surprisingly, only response strength, not timing,
             predicted task performance. Intervals perceived as longer
             were associated with larger visual responses and shorter
             intervals with smaller responses, matching the dynamics of
             adaptation. These results suggest that the magnitude of
             prefrontal activity may be read out to provide temporal
             information that contributes to judging the passage of
             time.},
   Doi = {10.1073/pnas.1217177110},
   Key = {fds334807}
}

@article{fds334811,
   Author = {Shin, S and Sommer, MA},
   Title = {Division of labor in frontal eye field neurons during
             presaccadic remapping of visual receptive
             fields.},
   Journal = {Journal of Neurophysiology},
   Volume = {108},
   Number = {8},
   Pages = {2144-2159},
   Year = {2012},
   Month = {October},
   url = {https://dl.dropbox.com/u/27738651/Publications/ShinSommer2012.pdf},
   Abstract = {Our percept of visual stability across saccadic eye
             movements may be mediated by presaccadic remapping. Just
             before a saccade, neurons that remap become visually
             responsive at a future field (FF), which anticipates the
             saccade vector. Hence, the neurons use corollary discharge
             of saccades. Many of the neurons also decrease their
             response at the receptive field (RF). Presaccadic remapping
             occurs in several brain areas including the frontal eye
             field (FEF), which receives corollary discharge of saccades
             in its layer IV from a collicular-thalamic pathway. We
             studied, at two levels, the microcircuitry of remapping in
             the FEF. At the laminar level, we compared remapping between
             layers IV and V. At the cellular level, we compared
             remapping between different neuron types of layer IV. In the
             FEF in four monkeys (Macaca mulatta), we identified 27 layer
             IV neurons with orthodromic stimulation and 57 layer V
             neurons with antidromic stimulation from the superior
             colliculus. With the use of established criteria, we
             classified the layer IV neurons as putative excitatory (n =
             11), putative inhibitory (n = 12), or ambiguous (n = 4). We
             found that just before a saccade, putative excitatory
             neurons increased their visual response at the RF, putative
             inhibitory neurons showed no change, and ambiguous neurons
             increased their visual response at the FF. None of the
             neurons showed presaccadic visual changes at both RF and FF.
             In contrast, neurons in layer V showed full remapping (at
             both the RF and FF). Our data suggest that elemental signals
             for remapping are distributed across neuron types in early
             cortical processing and combined in later stages of cortical
             microcircuitry.},
   Doi = {10.1152/jn.00204.2012},
   Key = {fds334811}
}

@article{fds334808,
   Author = {Mayo, JP and DiTomasso, A and Sommer, M and Smith,
             MA},
   Title = {An improved method for mapping neuronal receptive fields in
             prefrontal cortex},
   Journal = {Journal of Vision},
   Volume = {12},
   Number = {9},
   Pages = {81-81},
   Publisher = {Association for Research in Vision and Ophthalmology
             (ARVO)},
   Year = {2012},
   Month = {August},
   url = {http://dx.doi.org/10.1167/12.9.81},
   Doi = {10.1167/12.9.81},
   Key = {fds334808}
}

@article{fds334810,
   Author = {Middlebrooks, PG and Sommer, MA},
   Title = {Neuronal correlates of metacognition in primate frontal
             cortex.},
   Journal = {Neuron},
   Volume = {75},
   Number = {3},
   Pages = {517-530},
   Year = {2012},
   Month = {August},
   ISSN = {08966273},
   url = {https://dl.dropbox.com/u/27738651/Publications/MiddlebrooksSommer2012-MetacogNeurons-TextSupplPreview.pdf},
   Abstract = {Humans are metacognitive: they monitor and control their
             cognition. Our hypothesis was that neuronal correlates of
             metacognition reside in the same brain areas responsible for
             cognition, including frontal cortex. Recent work
             demonstrated that nonhuman primates are capable of
             metacognition, so we recorded from single neurons in the
             frontal eye field, dorsolateral prefrontal cortex, and
             supplementary eye field of monkeys (Macaca mulatta) that
             performed a metacognitive visual-oculomotor task. The
             animals made a decision and reported it with a saccade, but
             received no immediate reward or feedback. Instead, they had
             to monitor their decision and bet whether it was correct.
             Activity was correlated with decisions and bets in all three
             brain areas, but putative metacognitive activity that linked
             decisions to appropriate bets occurred exclusively in the
             SEF. Our results offer a survey of neuronal correlates of
             metacognition and implicate the SEF in linking cognitive
             functions over short periods of time.},
   Doi = {10.1016/j.neuron.2012.05.028},
   Key = {fds334810}
}

@article{fds334809,
   Author = {Crapse, TB and Sommer, MA},
   Title = {Frontal eye field neurons assess visual stability across
             saccades.},
   Journal = {The Journal of Neuroscience : the Official Journal of the
             Society for Neuroscience},
   Volume = {32},
   Number = {8},
   Pages = {2835-2845},
   Year = {2012},
   Month = {February},
   ISSN = {0270-6474},
   url = {https://dl.dropbox.com/u/27738651/Publications/CrapseSommer2012.pdf},
   Abstract = {The image on the retina may move because the eyes move, or
             because something in the visual scene moves. The brain is
             not fooled by this ambiguity. Even as we make saccades, we
             are able to detect whether visual objects remain stable or
             move. Here we test whether this ability to assess visual
             stability across saccades is present at the single-neuron
             level in the frontal eye field (FEF), an area that receives
             both visual input and information about imminent saccades.
             Our hypothesis was that neurons in the FEF report whether a
             visual stimulus remains stable or moves as a saccade is
             made. Monkeys made saccades in the presence of a visual
             stimulus outside of the receptive field. In some trials, the
             stimulus remained stable, but in other trials, it moved
             during the saccade. In every trial, the stimulus occupied
             the center of the receptive field after the saccade, thus
             evoking a reafferent visual response. We found that many FEF
             neurons signaled, in the strength and timing of their
             reafferent response, whether the stimulus had remained
             stable or moved. Reafferent responses were tuned for the
             amount of stimulus translation, and, in accordance with
             human psychophysics, tuning was better (more prevalent,
             stronger, and quicker) for stimuli that moved perpendicular,
             rather than parallel, to the saccade. Tuning was sometimes
             present as well for nonspatial transaccadic changes (in
             color, size, or both). Our results indicate that FEF neurons
             evaluate visual stability during saccades and may be general
             purpose detectors of transaccadic visual
             change.},
   Doi = {10.1523/JNEUROSCI.1320-11.2012},
   Key = {fds334809}
}

@article{fds334813,
   Author = {Basso, MA and Sommer, MA},
   Title = {Exploring the role of the substantia nigra pars reticulata
             in eye movements.},
   Journal = {Neuroscience},
   Volume = {198},
   Pages = {205-212},
   Year = {2011},
   Month = {December},
   url = {http://dx.doi.org/10.1016/j.neuroscience.2011.08.026},
   Abstract = {Experiments that demonstrated a role for the substantia
             nigra in eye movements have played an important role in our
             understanding of the function of the basal ganglia in
             behavior more broadly. In this review we explore more recent
             experiments that extend the role of the substantia nigra
             pars reticulata from a simple gate for eye movements to
             include a role in cognitive processes for eye movements. We
             review recent evidence suggesting that basal ganglia nuclei
             beyond the substantia nigra may also play a role in eye
             movements and the cognitive events leading up to the
             production of eye movements. We close by pointing out some
             unresolved questions in our understanding of the
             relationship of basal ganglia nuclei and eye
             movements.},
   Doi = {10.1016/j.neuroscience.2011.08.026},
   Key = {fds334813}
}

@article{Sommer2009,
   Author = {Middlebrooks, PG and Sommer, MA},
   Title = {Metacognition in monkeys during an oculomotor
             task.},
   Journal = {Journal of Experimental Psychology. Learning, Memory, and
             Cognition},
   Volume = {37},
   Number = {2},
   Pages = {325-337},
   Year = {2011},
   Month = {March},
   ISSN = {0278-7393},
   url = {https://dl.dropbox.com/u/27738651/Publications/MiddlebrooksSommer2011-MetacognitionInMonkeys.pdf},
   Abstract = {This study investigated whether rhesus monkeys show evidence
             of metacognition in a reduced, visual oculomotor task that
             is particularly suitable for use in fMRI and
             electrophysiology. The 2-stage task involved punctate visual
             stimulation and saccadic eye movement responses. In each
             trial, monkeys made a decision and then made a bet. To earn
             maximum reward, they had to monitor their decision and use
             that information to bet advantageously. Two monkeys learned
             to base their bets on their decisions within a few weeks. We
             implemented an operational definition of metacognitive
             behavior that relied on trial-by-trial analyses and signal
             detection theory. Both monkeys exhibited metacognition
             according to these quantitative criteria. Neither external
             visual cues nor potential reaction time cues explained the
             betting behavior; the animals seemed to rely exclusively on
             internal traces of their decisions. We documented the
             learning process of one monkey. During a 10-session
             transition phase, betting switched from random to a
             decision-based strategy. The results reinforce previous
             findings of metacognitive ability in monkeys and may
             facilitate the neurophysiological investigation of
             metacognitive functions.},
   Doi = {10.1037/a0021611},
   Key = {Sommer2009}
}

@article{fds334814,
   Author = {Crapse, T and Sommer, M},
   Title = {Translation of a visual stimulus during a saccade is more
             detectable if it moves perpendicular, rather than parallel,
             to the saccade},
   Journal = {Journal of Vision},
   Volume = {10},
   Number = {7},
   Pages = {521-521},
   Publisher = {Association for Research in Vision and Ophthalmology
             (ARVO)},
   Year = {2010},
   Month = {August},
   url = {http://dx.doi.org/10.1167/10.7.521},
   Doi = {10.1167/10.7.521},
   Key = {fds334814}
}

@article{fds334815,
   Author = {Shin, S and Sommer, MA},
   Title = {Activity of neurons in monkey globus pallidus during
             oculomotor behavior compared with that in substantia nigra
             pars reticulata.},
   Journal = {Journal of Neurophysiology},
   Volume = {103},
   Number = {4},
   Pages = {1874-1887},
   Year = {2010},
   Month = {April},
   ISSN = {0022-3077},
   url = {https://dl.dropbox.com/u/27738651/Publications/ShinSommer2010.pdf},
   Abstract = {The basal ganglia are a subcortical assembly of nuclei
             involved in many aspects of behavior. Three of the nuclei
             have high firing rates and inhibitory influences: the
             substantia nigra pars reticulata (SNr), globus pallidus
             interna (GPi), and globus pallidus externa (GPe). The SNr
             contains a wide range of visual, cognitive, and motor
             signals that have been shown to contribute to saccadic eye
             movements. Our hypothesis was that GPe and GPi neurons carry
             similarly diverse signals during saccadic behavior. We
             recorded from GPe, GPi, and SNr neurons in monkeys that made
             memory-guided saccades and found that neurons in all three
             structures had increases or decreases in activity
             synchronized with saccade generation, visual stimulation, or
             reward. Comparing GPe neurons with GPi neurons, we found
             relatively more visual-related activity in GPe and more
             reward-related activity in GPi. Comparing both pallidal
             samples with the SNr, we found a greater resemblance between
             GPe and SNr neurons than that between GPi and SNr neurons.
             As expected from a known inhibitory projection from GPe to
             SNr, there was a general reversal of sign in activity
             modulations between the structures: bursts of activity were
             relatively more common in GPe and pauses more common in SNr.
             We analyzed the response fields of neurons in all three
             structures and found relatively narrow and lateralized
             fields early in trials (during visual and saccadic events)
             followed by a broadening later in trials (during reward).
             Our data reinforce an emerging, new consensus that the GPe
             and GPi, in addition to the SNr, contribute to oculomotor
             behavior.},
   Doi = {10.1152/jn.00101.2009},
   Key = {fds334815}
}

@article{fds334816,
   Author = {Mayo, JP and Sommer, MA},
   Title = {Shifting attention to neurons},
   Journal = {Trends in Cognitive Sciences},
   Volume = {14},
   Number = {9},
   Pages = {389-389},
   Year = {2010},
   url = {http://dx.doi.org/10.1016/j.tics.2010.06.003},
   Doi = {10.1016/j.tics.2010.06.003},
   Key = {fds334816}
}

@article{fds334817,
   Author = {Sommer, MA},
   Title = {How the visual system monitors where the eyes will
             move},
   Journal = {Journal of Vision},
   Volume = {9},
   Number = {14},
   Pages = {13-13},
   Publisher = {Association for Research in Vision and Ophthalmology
             (ARVO)},
   Year = {2009},
   Month = {December},
   url = {http://dx.doi.org/10.1167/9.14.13},
   Doi = {10.1167/9.14.13},
   Key = {fds334817}
}

@article{fds334818,
   Author = {Sommer, MA},
   Title = {Corollary discharge circuits for stabilizing visual
             perception},
   Journal = {Psychophysiology},
   Volume = {46},
   Pages = {S9-S9},
   Publisher = {WILEY-BLACKWELL PUBLISHING, INC},
   Year = {2009},
   Month = {September},
   Key = {fds334818}
}

@article{fds334819,
   Author = {Mayo, JP and Sommer, MA},
   Title = {Monkey and human performance in a chronostasis task suitable
             for neurophysiology},
   Journal = {Journal of Vision},
   Volume = {9},
   Number = {8},
   Pages = {406-406},
   Publisher = {Association for Research in Vision and Ophthalmology
             (ARVO)},
   Year = {2009},
   Month = {August},
   url = {http://dx.doi.org/10.1167/9.8.406},
   Doi = {10.1167/9.8.406},
   Key = {fds334819}
}

@article{Crapse2009,
   Author = {Crapse, TB and Sommer, MA},
   Title = {Frontal eye field neurons with spatial representations
             predicted by their subcortical input.},
   Journal = {The Journal of Neuroscience : the Official Journal of the
             Society for Neuroscience},
   Volume = {29},
   Number = {16},
   Pages = {5308-5318},
   Year = {2009},
   Month = {April},
   ISSN = {0270-6474},
   url = {https://dl.dropbox.com/u/27738651/Publications/CrapseSommer2009_JNeurosci.pdf},
   Abstract = {The frontal eye field (FEF) is a cortical structure involved
             in cognitive aspects of eye movement control. Neurons in the
             FEF, as in most of cerebral cortex, primarily represent
             contralateral space. They fire for visual stimuli in the
             contralateral field and for saccadic eye movements made to
             those stimuli. Yet many FEF neurons engage in sophisticated
             functions that require flexible spatial representations such
             as shifting receptive fields and vector subtraction. Such
             functions require knowledge about all of space, including
             the ipsilateral hemifield. How does the FEF gain access to
             ipsilateral information? Here, we provide evidence that one
             source of ipsilateral information may be the opposite
             superior colliculus (SC) in the midbrain. We physiologically
             identified neurons in the FEF that receive input from the
             opposite SC, same-side SC, or both. We found a striking
             structure-function relationship: the laterality of the
             response field of an FEF neuron was predicted by the
             laterality of its SC inputs. FEF neurons with input from the
             opposite SC had ipsilateral fields, whereas neurons with
             input from the same-side SC had contralateral fields. FEF
             neurons with input from both SCs had lateralized fields that
             could point in any direction. The results suggest that
             signals from the two SCs provide each FEF with information
             about all of visual space, a prerequisite for higher level
             sensorimotor computations.},
   Doi = {10.1523/JNEUROSCI.4906-08.2009},
   Key = {Crapse2009}
}

@article{Crapse2008a,
   Author = {Crapse, TB and Sommer, MA},
   Title = {Corollary discharge circuits in the primate
             brain.},
   Journal = {Current Opinion in Neurobiology},
   Volume = {18},
   Number = {6},
   Pages = {552-557},
   Year = {2008},
   Month = {December},
   ISSN = {0959-4388},
   url = {https://dl.dropbox.com/u/27738651/Publications/CrapseSommer_CurrOpinionNeurobiology2008.pdf},
   Abstract = {Movements are necessary to engage the world, but every
             movement results in sensorimotor ambiguity. Self-movements
             cause changes to sensory inflow as well as changes in the
             positions of objects relative to motor effectors (eyes and
             limbs). Hence the brain needs to monitor self-movements, and
             one way this is accomplished is by routing copies of
             movement commands to appropriate structures. These signals,
             known as corollary discharge (CD), enable compensation for
             sensory consequences of movement and preemptive updating of
             spatial representations. Such operations occur with a speed
             and accuracy that implies a reliance on prediction. Here we
             review recent CD studies and find that they arrive at a
             shared conclusion: CD contributes to prediction for the sake
             of sensorimotor harmony.},
   Doi = {10.1016/j.conb.2008.09.017},
   Key = {Crapse2008a}
}

@article{Mayo2008a,
   Author = {Mayo, JP and Sommer, MA},
   Title = {Neuronal adaptation caused by sequential visual stimulation
             in the frontal eye field.},
   Journal = {Journal of Neurophysiology},
   Volume = {100},
   Number = {4},
   Pages = {1923-1935},
   Year = {2008},
   Month = {October},
   ISSN = {0022-3077},
   url = {https://dl.dropbox.com/u/27738651/Publications/MayoSommer2008-FEFadaptation.pdf},
   Abstract = {Images on the retina can change drastically in only a few
             milliseconds. A robust description of visual temporal
             processing is therefore necessary to understand visual
             analysis in the real world. To this end, we studied
             subsecond visual changes and asked how prefrontal neurons in
             monkeys respond to stimuli presented in quick succession. We
             recorded the visual responses of single neurons in the
             frontal eye field (FEF), a prefrontal area polysynaptically
             removed from the retina that is involved with higher level
             cognition. For comparison, we also recorded from small
             groups of neurons in the superficial superior colliculus
             (supSC), an area that receives direct retinal input. Two
             sequential flashes of light at varying interstimulus
             intervals were presented in a neuron's receptive field. We
             found pervasive neuronal adaptation in FEF and supSC. Visual
             responses to the second stimulus were diminished for up to
             half a second after the first stimulus presentation.
             Adaptation required a similar amount of time to return to
             full responsiveness in both structures, but there was
             significantly more neuronal adaptation overall in FEF.
             Adaptation was not affected by saccades, although visual
             responses to single stimuli were transiently suppressed
             postsaccadically. Our FEF and supSC results systematically
             document subsecond visual adaptation in prefrontal cortex
             and show that this adaptation is comparable to, but stronger
             than, adaptation found earlier in the visual
             system.},
   Doi = {10.1152/jn.90549.2008},
   Key = {Mayo2008a}
}

@article{Crapse2008b,
   Author = {Crapse, TB and Sommer, MA},
   Title = {Corollary discharge across the animal kingdom.},
   Journal = {Nature Reviews. Neuroscience},
   Volume = {9},
   Number = {8},
   Pages = {587-600},
   Year = {2008},
   Month = {August},
   ISSN = {1471-0048},
   url = {https://dl.dropbox.com/u/27738651/Publications/CrapseSommer_CDReview2008.pdf},
   Abstract = {Our movements can hinder our ability to sense the world.
             Movements can induce sensory input (for example, when you
             hit something) that is indistinguishable from the input that
             is caused by external agents (for example, when something
             hits you). It is critical for nervous systems to be able to
             differentiate between these two scenarios. A ubiquitous
             strategy is to route copies of movement commands to sensory
             structures. These signals, which are referred to as
             corollary discharge (CD), influence sensory processing in
             myriad ways. Here we review the CD circuits that have been
             uncovered by neurophysiological studies and suggest a
             functional taxonomic classification of CD across the animal
             kingdom. This broad understanding of CD circuits lays the
             groundwork for more challenging studies that combine
             neurophysiology and psychophysics to probe the role of CD in
             perception.},
   Doi = {10.1038/nrn2457},
   Key = {Crapse2008b}
}

@article{Mayo2008b,
   Author = {Mayo, JP and Sommer, MA},
   Title = {Neuronal adaptation: Delay compensation at the level of
             single neurons?},
   Journal = {Behavioral and Brain Sciences},
   Volume = {31},
   Number = {2},
   Pages = {210-212},
   Publisher = {Cambridge University Press (CUP)},
   Year = {2008},
   Month = {April},
   ISSN = {0140-525X},
   url = {https://dl.dropbox.com/u/27738651/Publications/MayoSommer2008-BBScommentary.pdf},
   Abstract = {Saccades divide visual input into rapid, discontinuous
             periods of stimulation on the retina. The response of single
             neurons to such sequential stimuli is neuronal adaptation; a
             robust first response followed by an interval-dependent
             diminished second response. Adaptation is pervasive in both
             early and late stages of visual processing. Given its
             inherent coding of brief time intervals, neuronal adaptation
             may play a fundamental role in compensating for visual
             delays. © 2008 Cambridge University Press
             2008.},
   Doi = {10.1017/S0140525X08003944},
   Key = {Mayo2008b}
}

@article{Sommer2008a,
   Author = {Sommer, MA and Wurtz, RH},
   Title = {Brain circuits for the internal monitoring of
             movements.},
   Journal = {Annual Review of Neuroscience},
   Volume = {31},
   Pages = {317-338},
   Year = {2008},
   Month = {January},
   ISSN = {0147-006X},
   url = {https://dl.dropbox.com/u/27738651/Publications/SommerWurtz_AnnualRevNeurosci2008.pdf},
   Abstract = {Each movement we make activates our own sensory receptors,
             thus causing a problem for the brain: the spurious,
             movement-related sensations must be discriminated from the
             sensory inputs that really matter, those representing our
             environment. Here we consider circuits for solving this
             problem in the primate brain. Such circuits convey a copy of
             each motor command, known as a corollary discharge (CD), to
             brain regions that use sensory input. In the visual system,
             CD signals may help to produce a stable visual percept from
             the jumpy images resulting from our rapid eye movements. A
             candidate pathway for providing CD for vision ascends from
             the superior colliculus to the frontal cortex in the primate
             brain. This circuit conveys warning signals about impending
             eye movements that are used for planning subsequent
             movements and analyzing the visual world. Identifying this
             circuit has provided a model for studying CD in other
             primate sensory systems and may lead to a better
             understanding of motor and mental disorders.},
   Doi = {10.1146/annurev.neuro.31.060407.125627},
   Key = {Sommer2008a}
}

@article{Sommer2008b,
   Author = {Sommer, MA and Wurtz, RH},
   Title = {Visual perception and corollary discharge.},
   Journal = {Perception},
   Volume = {37},
   Number = {3},
   Pages = {408-418},
   Year = {2008},
   Month = {January},
   ISSN = {0301-0066},
   url = {https://dl.dropbox.com/u/27738651/Publications/SommerWurtz2008-Perception.pdf},
   Abstract = {Perception depends not only on sensory input but also on the
             state of the brain receiving that input. A classic example
             is perception of a stable visual world in spite of the
             saccadic eye movements that shift the images on the retina.
             A long-standing hypothesis is that the brain compensates for
             the disruption of visual input by using advance knowledge of
             the impending saccade, an internally generated corollary
             discharge. One possible neuronal mechanism for this
             compensation has been previously identified in parietal and
             frontal cortex of monkeys, but the origin of the necessary
             corollary discharge remained unknown. Here, we consider
             recent experiments that identified a pathway for a corollary
             discharge for saccades that extends from the superior
             colliculus in the midbrain to the frontal eye fields in the
             cerebral cortex with a relay in the medial dorsal nucleus of
             the thalamus. We first review the nature of the evidence
             used to identify a corollary discharge signal in the
             complexity of the primate brain and show its use for guiding
             a rapid sequence of eye movements. We then consider two
             experiments that show this same corollary signal may provide
             the input to the frontal cortex neurons that alters their
             activity with saccades in ways that could compensate for the
             displacements in the visual input produced by saccadic eye
             movements. The first experiment shows that the corollary
             discharge signal is spatially and temporally appropriate to
             produce the alterations in the frontal-cortex neurons. The
             second shows that this signal is necessary for this
             alteration because inactivation of the corollary reduces the
             compensation by frontal-cortex neurons. The identification
             of this relatively simple circuit specifies the organization
             of a corollary discharge in the primate brain for the first
             time and provides a specific example upon which
             consideration of the roles of corollary activity in other
             systems and for other functions can be evaluated.},
   Doi = {10.1068/p5873},
   Key = {Sommer2008b}
}

@article{fds334831,
   Author = {Crapse, TB and Sommer, MA},
   Title = {The frontal eye field as a prediction map.},
   Journal = {Progress in Brain Research},
   Volume = {171},
   Pages = {383-390},
   Editor = {C. Kennard and R. J. Leigh},
   Year = {2008},
   Month = {January},
   ISSN = {0079-6123},
   url = {https://dl.dropbox.com/u/27738651/Publications/CrapseSommer_ProgressBrainRes2008.pdf},
   Abstract = {Predictive processes are widespread in the motor and sensory
             areas of the primate brain. They enable rapid computations
             despite processing delays and assist in resolving noisy,
             ambiguous input. Here we propose that the frontal eye field,
             a cortical area devoted to sensorimotor aspects of eye
             movement control, implements a prediction map of the
             postsaccadic visual scene for the purpose of constructing a
             stable percept despite saccadic eye movements.},
   Doi = {10.1016/S0079-6123(08)00656-0},
   Key = {fds334831}
}

@article{Sommer2007a,
   Author = {Sommer, MA},
   Title = {Microcircuits for attention.},
   Journal = {Neuron},
   Volume = {55},
   Number = {1},
   Pages = {6-8},
   Year = {2007},
   Month = {July},
   ISSN = {0896-6273},
   url = {https://dl.dropbox.com/u/27738651/Publications/Sommer2007-NeuronCommentary.pdf},
   Abstract = {Researchers who study the neuronal basis of cognition face a
             paradox. If they extract the brain, its cognitive functions
             cannot be assessed. On the other hand, the brain's
             microcircuits are difficult to study in the intact animal.
             In this issue of Neuron, Mitchell et al. make use of a
             promising approach based on waveform analysis to reveal new
             details about neuronal interactions during visual
             attention.},
   Doi = {10.1016/j.neuron.2007.06.022},
   Key = {Sommer2007a}
}

@article{Sommer2007b,
   Author = {Sommer, MA},
   Title = {The feeling of looking.},
   Journal = {Nature Neuroscience},
   Volume = {10},
   Number = {5},
   Pages = {538-540},
   Year = {2007},
   Month = {May},
   ISSN = {1097-6256},
   url = {https://dl.dropbox.com/u/27738651/Publications/Sommer2007-FeelingOfLooking.pdf},
   Abstract = {Sensory cortex area 3a contains a map of the body. A new
             paper reports the location of eye position signals in this
             map which should allow researchers to test the functions of
             eye position signals and visual gain fields in more detail.
             © 2007 Nature Publishing Group.},
   Doi = {10.1038/nn0507-538},
   Key = {Sommer2007b}
}

@article{Sommer2006,
   Author = {Sommer, MA and Wurtz, RH},
   Title = {Influence of the thalamus on spatial visual processing in
             frontal cortex.},
   Journal = {Nature},
   Volume = {444},
   Number = {7117},
   Pages = {374-377},
   Year = {2006},
   Month = {November},
   ISSN = {0028-0836},
   url = {https://dl.dropbox.com/u/27738651/Publications/SommerWurtz2006_Nature_Reprint.pdf},
   Abstract = {Each of our movements activates our own sensory receptors,
             and therefore keeping track of self-movement is a necessary
             part of analysing sensory input. One way in which the brain
             keeps track of self-movement is by monitoring an internal
             copy, or corollary discharge, of motor commands. This
             concept could explain why we perceive a stable visual world
             despite our frequent quick, or saccadic, eye movements:
             corollary discharge about each saccade would permit the
             visual system to ignore saccade-induced visual changes. The
             critical missing link has been the connection between
             corollary discharge and visual processing. Here we show that
             such a link is formed by a corollary discharge from the
             thalamus that targets the frontal cortex. In the thalamus,
             neurons in the mediodorsal nucleus relay a corollary
             discharge of saccades from the midbrain superior colliculus
             to the cortical frontal eye field. In the frontal eye field,
             neurons use corollary discharge to shift their visual
             receptive fields spatially before saccades. We tested the
             hypothesis that these two components-a pathway for corollary
             discharge and neurons with shifting receptive fields-form a
             circuit in which the corollary discharge drives the shift.
             First we showed that the known spatial and temporal
             properties of the corollary discharge predict the dynamic
             changes in spatial visual processing of cortical neurons
             when saccades are made. Then we moved from this correlation
             to causation by isolating single cortical neurons and
             showing that their spatial visual processing is impaired
             when corollary discharge from the thalamus is interrupted.
             Thus the visual processing of frontal neurons is
             spatiotemporally matched with, and functionally dependent
             on, corollary discharge input from the thalamus. These
             experiments establish the first link between corollary
             discharge and visual processing, delineate a brain circuit
             that is well suited for mediating visual stability, and
             provide a framework for studying corollary discharge in
             other sensory systems.},
   Doi = {10.1038/nature05279},
   Key = {Sommer2006}
}

@article{fds334835,
   Author = {Wurtz, RH and Sommer, MA},
   Title = {A corollary discharge for perceptual stability},
   Journal = {Perception},
   Volume = {35},
   Pages = {10-11},
   Publisher = {SAGE PUBLICATIONS LTD},
   Year = {2006},
   Month = {January},
   Key = {fds334835}
}

@article{fds334836,
   Author = {Wurtz, RH and Sommer, MA and Cavanaugh, J},
   Title = {Drivers from the deep: the contribution of collicular input
             to thalamocortical processing.},
   Journal = {Progress in Brain Research},
   Volume = {149},
   Pages = {207-225},
   Year = {2005},
   Month = {January},
   ISSN = {0079-6123},
   url = {https://dl.dropbox.com/u/27738651/Publications/WurtzSommerCavanaugh_ProgrBrainRes2005.pdf},
   Abstract = {A traditional view of the thalamus is that it is a relay
             station which receives sensory input and conveys this
             information to cortex. This sensory input determines most of
             the properties of first order thalamic neurons, and so is
             said to drive, rather than modulate, these neurons. This
             holds as a rule for first order thalamic nuclei, but in
             contrast, higher order thalamic nuclei receive much of their
             driver input back from cerebral cortex. In addition, higher
             order thalamic neurons receive inputs from subcortical
             movement-related centers. In the terminology popularized
             from studies of the sensory system, can we consider these
             ascending motor inputs to thalamus from subcortical
             structures to be modulators, subtly influencing the activity
             of their target neurons, or drivers, dictating the activity
             of their target neurons? This chapter summarizes relevant
             evidence from neuronal recording, inactivation, and
             stimulation of pathways projecting from the superior
             colliculus through thalamus to cerebral cortex. The study
             concludes that many inputs to the higher order nuclei of the
             thalamus from subcortical oculomotor areas - from the
             superior colliculus and probably other midbrain and pontine
             regions - should be regarded as motor drivers analogous to
             the sensory drivers at the first order thalamic nuclei.
             These motor drivers at the thalamus are viewed as being at
             the top of a series of feedback loops that provide
             information on impending actions, just as sensory drivers
             provide information about the external environment.},
   Doi = {10.1016/s0079-6123(05)49015-9},
   Key = {fds334836}
}

@article{fds334838,
   Author = {Sommer, MA and Wurtz, RH},
   Title = {What the brain stem tells the frontal cortex. II. Role of
             the SC-MD-FEF pathway in corollary discharge.},
   Journal = {Journal of Neurophysiology},
   Volume = {91},
   Number = {3},
   Pages = {1403-1423},
   Year = {2004},
   Month = {March},
   url = {http://dx.doi.org/10.1152/jn.00740.2003},
   Abstract = {One way we keep track of our movements is by monitoring
             corollary discharges or internal copies of movement
             commands. This study tested a hypothesis that the pathway
             from superior colliculus (SC) to mediodorsal thalamus (MD)
             to frontal eye field (FEF) carries a corollary discharge
             about saccades made into the contralateral visual field. We
             inactivated the MD relay node with muscimol in monkeys and
             measured corollary discharge deficits using a double-step
             task: two sequential saccades were made to the locations of
             briefly flashed targets. To make second saccades correctly,
             monkeys had to internally monitor their first saccades;
             therefore deficits in the corollary discharge representation
             of first saccades should disrupt second saccades. We found,
             first, that monkeys seemed to misjudge the amplitudes of
             their first saccades; this was revealed by systematic shifts
             in second saccade end points. Thus corollary discharge
             accuracy was impaired. Second, monkeys were less able to
             detect trial-by-trial variations in their first saccades;
             this was revealed by reduced compensatory changes in second
             saccade angles. Thus corollary discharge precision also was
             impaired. Both deficits occurred only when first saccades
             went into the contralateral visual field. Single-saccade
             generation was unaffected. Additional deficits occurred in
             reaction time and overall performance, but these were
             bilateral. We conclude that the SC-MD-FEF pathway conveys a
             corollary discharge used for coordinating sequential
             saccades and possibly for stabilizing vision across
             saccades. This pathway is the first elucidated in what may
             be a multilevel chain of corollary discharge circuits
             extending from the extraocular motoneurons up into cerebral
             cortex.},
   Doi = {10.1152/jn.00740.2003},
   Key = {fds334838}
}

@article{fds334839,
   Author = {Sommer, MA and Wurtz, RH},
   Title = {What the brain stem tells the frontal cortex. I. Oculomotor
             signals sent from superior colliculus to frontal eye field
             via mediodorsal thalamus.},
   Journal = {Journal of Neurophysiology},
   Volume = {91},
   Number = {3},
   Pages = {1381-1402},
   Year = {2004},
   Month = {March},
   url = {http://dx.doi.org/10.1152/jn.00738.2003},
   Abstract = {Neuronal processing in cerebral cortex and signal
             transmission from cortex to brain stem have been studied
             extensively, but little is known about the numerous feedback
             pathways that ascend from brain stem to cortex. In this
             study, we characterized the signals conveyed through an
             ascending pathway coursing from the superior colliculus (SC)
             to the frontal eye field (FEF) via mediodorsal thalamus
             (MD). Using antidromic and orthodromic stimulation, we
             identified SC source neurons, MD relay neurons, and FEF
             recipient neurons of the pathway in Macaca mulatta. The
             monkeys performed oculomotor tasks, including
             delayed-saccade tasks, that permitted analysis of signals
             such as visual activity, delay activity, and presaccadic
             activity. We found that the SC sends all of these signals
             into the pathway with no output selectivity, i.e., the
             signals leaving the SC resembled those found generally
             within the SC. Visual activity arrived in FEF too late to
             contribute to short-latency visual responses there, and
             delay activity was largely filtered out in MD. Presaccadic
             activity, however, seemed critical because it traveled
             essentially unchanged from SC to FEF. Signal transmission in
             the pathway was fast ( approximately 2 ms from SC to FEF)
             and topographically organized (SC neurons drove MD and FEF
             neurons having similarly eccentric visual and movement
             fields). Our analysis of identified neurons in one pathway
             from brain stem to frontal cortex thus demonstrates that
             multiple signals are sent from SC to FEF with presaccadic
             activity being prominent. We hypothesize that a major signal
             conveyed by the pathway is corollary discharge information
             about the vector of impending saccades.},
   Doi = {10.1152/jn.00738.2003},
   Key = {fds334839}
}

@article{fds334837,
   Author = {Wurtz, RH and Sommer, MA},
   Title = {Identifying corollary discharges for movement in the primate
             brain.},
   Journal = {Progress in Brain Research},
   Volume = {144},
   Pages = {47-60},
   Year = {2004},
   Month = {January},
   ISSN = {0079-6123},
   url = {https://dl.dropbox.com/u/27738651/Publications/WurtzSommer_ProgBrainRes2004.pdf},
   Abstract = {The brain keeps track of the movements it makes so as to
             process sensory input accurately and coordinate complex
             movements gracefully. In this chapter we review the brain's
             strategies for keeping track of fast, saccadic eye
             movements. One way it does this is by monitoring copies of
             saccadic motor commands, or corollary discharges. It has
             been difficult to identify corollary discharge signals in
             the primate brain, although in some studies the influence of
             corollary discharge, for example on visual processing, has
             been found. We propose four criteria for identifying
             corollary discharge signals in primate brain based on our
             experiences studying a pathway from superior colliculus, in
             the brainstem, through mediodorsal thalamus to frontal eye
             field, in the prefrontal cortex. First, the signals must
             originate from a brain structure involved in generating
             movements. Second, they must begin just prior to movements
             and represent spatial attributes of the movements. Third,
             eliminating the signals should not impair movements in
             simple tasks not requiring corollary discharge. Fourth,
             eliminating the signals should, however, disrupt movements
             in tasks that require corollary discharge, such as a
             double-step task in which the monkey must keep track of one
             saccade in order to correctly generate another. Applying
             these criteria to the pathway from superior colliculus to
             frontal eye field, we concluded that it does indeed convey
             corollary discharge signals. The extent to which cerebral
             cortex actually uses these signals, particularly in the
             realm of sensory perception, remains unknown pending further
             studies. Moreover, many other ascending pathways from
             brainstem to cortex remain to be explored in behaving
             monkeys, and some of these, too, may carry corollary
             discharge signals.},
   Doi = {10.1016/s0079-6123(03)14403-2},
   Key = {fds334837}
}

@article{fds334841,
   Author = {Sommer, MA},
   Title = {The role of the thalamus in motor control.},
   Journal = {Current Opinion in Neurobiology},
   Volume = {13},
   Number = {6},
   Pages = {663-670},
   Year = {2003},
   Month = {December},
   url = {http://dx.doi.org/10.1016/j.conb.2003.10.014},
   Abstract = {Two characteristics of the thalamus--its apparently simple
             relay function and its daunting multinuclear structure--have
             been customarily viewed as good reasons to study something
             else. Yet, now that many other brain regions have been
             explored and neurophysiologists are turning to questions of
             how larger circuits operate, these two characteristics are
             starting to seem more attractive. First, the relay nature of
             thalamic neurons means that recording from them, like
             tapping into a wire, can reveal the signals carried by
             specific circuits. Second, the concentration of like relay
             neurons into nuclei means that inactivating or stimulating
             them can efficiently test the functions of the circuits.
             Recent studies implementing these principles have revealed
             pathways through the thalamus that contribute to generating
             movements and to monitoring one's own actions (corollary
             discharge).},
   Doi = {10.1016/j.conb.2003.10.014},
   Key = {fds334841}
}

@article{fds334840,
   Author = {Sommer, MA and Wurtz, RH},
   Title = {The frontal eye field sends predictively remapped visual
             signals to the superior colliculus},
   Journal = {Journal of Vision},
   Volume = {3},
   Number = {9},
   Pages = {146-146},
   Publisher = {Association for Research in Vision and Ophthalmology
             (ARVO)},
   Year = {2003},
   url = {http://dx.doi.org/10.1167/3.9.146},
   Abstract = {We perceive a stable visual world even though saccades often
             move our retinas. One way the brain may achieve a stable
             visual percept is through predictive remapping of visual
             receptive fields: just before a saccade, the receptive field
             of many neurons moves from its current location ("current
             receptive field") to the location it is expected to occupy
             after the saccade ("future receptive field"). Goldberg and
             colleagues found such remapping in cortical areas, e.g. in
             the frontal eye field (FEF), as well as in the intermediate
             layers of the superior colliculus (SC). In the present study
             we investigated the source of the SC's remapped visual
             signals. Do some of them come from the FEF? We identified
             FEF neurons that project to the SC using antidromic
             stimulation. For neurons with a visual response, we tested
             whether the receptive field shifted just prior to making a
             saccade. Saccadic amplitudes were chosen to be as small as
             possible while clearly separating the current and future
             receptive fields; they ranged from 5-30 deg. in amplitude
             and were directed contraversively. The saccadic target was a
             small red spot. We probed visual responsiveness at the
             current and future receptive field locations using a white
             spot flashed at various times before or after the saccade.
             Predictive remapping was indicated by a visual response to a
             probe flashed in the future receptive field just before the
             saccade began. We found that many FEF neurons projecting to
             the SC exhibited predictive remapping. Moreover, the
             remapping was as fast and strong as any previously reported
             for FEF or SC. It is clear, therefore, that remapped visual
             signals are sent from FEF to SC, providing direct evidence
             that the FEF is one source of the SC's remapped visual
             signals. Because remapping requires information about an
             imminent saccade, we hypothesize that remapping in FEF
             depends on corollary discharge signals such as those
             ascending from the SC through MD thalamus (Sommer and Wurtz
             2002).},
   Doi = {10.1167/3.9.146},
   Key = {fds334840}
}

@article{fds334842,
   Author = {Sommer, MA and Wurtz, RH},
   Title = {A pathway in primate brain for internal monitoring of
             movements.},
   Journal = {Science (New York, N.Y.)},
   Volume = {296},
   Number = {5572},
   Pages = {1480-1482},
   Year = {2002},
   Month = {May},
   ISSN = {0036-8075},
   url = {https://dl.dropbox.com/u/27738651/Publications/SommerWurtz2002.pdf},
   Abstract = {It is essential to keep track of the movements we make, and
             one way to do that is to monitor correlates, or corollary
             discharges, of neuronal movement commands. We hypothesized
             that a previously identified pathway from brainstem to
             frontal cortex might carry corollary discharge signals. We
             found that neuronal activity in this pathway encodes
             upcoming eye movements and that inactivating the pathway
             impairs sequential eye movements consistent with loss of
             corollary discharge without affecting single eye movements.
             These results identify a pathway in the brain of the primate
             Macaca mulatta that conveys corollary discharge
             signals.},
   Doi = {10.1126/science.1069590},
   Key = {fds334842}
}

@article{fds334845,
   Author = {Sommer, MA and Wurtz, RH},
   Title = {Frontal eye field sends delay activity related to movement,
             memory, and vision to the superior colliculus.},
   Journal = {Journal of Neurophysiology},
   Volume = {85},
   Number = {4},
   Pages = {1673-1685},
   Year = {2001},
   Month = {April},
   url = {http://dx.doi.org/10.1152/jn.2001.85.4.1673},
   Abstract = {Many neurons within prefrontal cortex exhibit a tonic
             discharge between visual stimulation and motor response.
             This delay activity may contribute to movement, memory, and
             vision. We studied delay activity sent from the frontal eye
             field (FEF) in prefrontal cortex to the superior colliculus
             (SC). We evaluated whether this efferent delay activity was
             related to movement, memory, or vision, to establish its
             possible functions. Using antidromic stimulation, we
             identified 66 FEF neurons projecting to the SC and we
             recorded from them while monkeys performed a Go/Nogo task.
             Early in every trial, a monkey was instructed as to whether
             it would have to make a saccade (Go) or not (Nogo) to a
             target location, which permitted identification of delay
             activity related to movement. In half of the trials (memory
             trials), the target disappeared, which permitted
             identification of delay activity related to memory. In the
             remaining trials (visual trials), the target remained
             visible, which permitted identification of delay activity
             related to vision. We found that 77% (51/66) of the FEF
             output neurons had delay activity. In 53% (27/51) of these
             neurons, delay activity was modulated by Go/Nogo
             instructions. The modulation preceded saccades made into
             only part of the visual field, indicating that the
             modulation was movement-related. In some neurons, delay
             activity was modulated by Go/Nogo instructions in both
             memory and visual trials and seemed to represent where to
             move in general. In other neurons, delay activity was
             modulated by Go/Nogo instructions only in memory trials,
             which suggested that it was a correlate of working memory,
             or only in visual trials, which suggested that it was a
             correlate of visual attention. In 47% (24/51) of FEF output
             neurons, delay activity was unaffected by Go/Nogo
             instructions, which indicated that the activity was related
             to the visual stimulus. In some of these neurons, delay
             activity occurred in both memory and visual trials and
             seemed to represent a coordinate in visual space. In others,
             delay activity occurred only in memory trials and seemed to
             represent transient visual memory. In the remainder, delay
             activity occurred only in visual trials and seemed to be a
             tonic visual response. In conclusion, the FEF sends diverse
             delay activity signals related to movement, memory, and
             vision to the SC, where the signals may be used for saccade
             generation. Downstream transmission of various delay
             activity signals may be an important, general way in which
             the prefrontal cortex contributes to the control of
             movement.},
   Doi = {10.1152/jn.2001.85.4.1673},
   Key = {fds334845}
}

@article{fds334843,
   Author = {Wurtz, RH and Sommer, MA and Paré, M and Ferraina,
             S},
   Title = {Signal transformations from cerebral cortex to superior
             colliculus for the generation of saccades.},
   Journal = {Vision Research},
   Volume = {41},
   Number = {25-26},
   Pages = {3399-3412},
   Year = {2001},
   Month = {January},
   ISSN = {0042-6989},
   url = {https://dl.dropbox.com/u/27738651/Publications/WurtzSommerPareFerraina2001.pdf},
   Abstract = {The ability of primates to make rapid and accurate saccadic
             eye movements for exploring the natural world is based on a
             neuronal system in the brain that has been studied
             extensively and is known to include multiple brain regions
             extending throughout the neuraxis. We examined the
             characteristics of signal flow in this system by recording
             from identified output neurons of two cortical regions, the
             lateral intraparietal area (LIP) and the frontal eye field
             (FEF), and from neurons in a brainstem structure targeted by
             these output neurons, the superior colliculus (SC). We
             compared the activity of neurons in these three populations
             while monkeys performed a delayed saccade task that allowed
             us to quantify visual responses, motor activity, and
             intervening delay activity. We examined whether delay
             activity was related to visual stimulation by comparing the
             activity during interleaved trials when a target was either
             present or absent during the delay period. We examined
             whether delay activity was related to movement by using a
             Go/Nogo task and comparing the activity during interleaved
             trials in which a saccade was either made (Go) or not
             (Nogo). We found that LIP output neurons, FEF output
             neurons, and SC neurons can all have visual responses, delay
             activity, and presaccadic bursts; hence in this way they are
             all quite similar. However, the delay activity tended to be
             more related to visual stimulation in the cortical output
             neurons than in the SC neurons. Complementing this, the
             delay activity tended to be more related to movement in the
             SC neurons than in the cortical output neurons. We conclude,
             first, that the signal flow leaving the cortex represents
             activity at nearly every stage of visuomotor transformation,
             and second, that there is a gradual evolution of signal
             processing as one proceeds from cortex to
             colliculus.},
   Doi = {10.1016/s0042-6989(01)00066-9},
   Key = {fds334843}
}

@article{fds334844,
   Author = {Sommer, M and Wurtz, R},
   Title = {A subcortical source of visual input to the frontal eye
             field},
   Journal = {Journal of Vision},
   Volume = {1},
   Number = {3},
   Pages = {259-259},
   Publisher = {Association for Research in Vision and Ophthalmology
             (ARVO)},
   Year = {2001},
   url = {http://dx.doi.org/10.1167/1.3.259},
   Abstract = {Many neurons in the frontal eye field (FEF) exhibit visual
             responses and are thought to play important roles in
             visuosaccadic behavior. The FEF, however, is far removed
             from striate cortex. Where do the FEF's visual signals come
             from? Usually they are reasonably assumed to enter the FEF
             through afferents from extrastriate cortex. Here we show
             that, surprisingly, visual signals also enter the FEF
             through a subcortical route: a disynaptic, ascending pathway
             originating in the intermediate layers of the superior
             colliculus (SC). We recorded from identified neurons at all
             three stages of this pathway (n=30-40 in each sample): FEF
             recipient neurons, orthodromically activated from the SC;
             mediodorsal thalamus (MD) relay neurons, antidromically
             activated from FEF and orthodromically activated from SC;
             and SC source neurons, antidromically activated from MD. We
             studied the neurons while monkeys performed delayed saccade
             tasks designed to temporally resolve visual responses from
             presaccadic discharges. We found, first, that most neurons
             at every stage in the pathway had visual responses,
             presaccadic bursts, or both. Second, we found marked
             similarities between the SC source neurons and MD relay
             neurons: in both samples, about 15% of the neurons had only
             a visual response, 10% had only a presaccadic burst, and 75%
             had both. In contrast, FEF recipient neurons tended to be
             more visual in nature: 50% had only a visual response, none
             had only a presaccadic burst, and 50% had both a visual
             response and a presaccadic burst. This suggests that in
             addition to their subcortical inputs, these FEF neurons also
             receive other visual inputs, e.g. from extrastriate cortex.
             We conclude that visual activity in the FEF results not only
             from cortical afferents but also from subcortical inputs.
             Intriguingly, this implies that some of the visual signals
             in FEF are pre-processed by the SC.},
   Doi = {10.1167/1.3.259},
   Key = {fds334844}
}

@article{fds334849,
   Author = {Port, NL and Sommer, MA and Wurtz, RH},
   Title = {Multielectrode evidence for spreading activity across the
             superior colliculus movement map.},
   Journal = {Journal of Neurophysiology},
   Volume = {84},
   Number = {1},
   Pages = {344-357},
   Year = {2000},
   Month = {July},
   url = {http://dx.doi.org/10.1152/jn.2000.84.1.344},
   Abstract = {The monkey superior colliculus (SC) has maps for both visual
             input and movement output in the superficial and
             intermediate layers, respectively, and activity on these
             maps is generally related to visual stimuli only in one part
             of the visual field and/or to a restricted range of saccadic
             eye movements to those stimuli. For some neurons within
             these maps, however, activity has been reported to spread
             from the caudal SC to the rostral SC during the course of a
             saccade. This spread of activity was inferred from averages
             of recordings at different sites on the SC movement map
             during saccades of different amplitudes and even in
             different monkeys. In the present experiments, SC activity
             was recorded simultaneously in pairs of neurons to observe
             the spread of activity during individual saccades. Two
             electrodes were positioned along the rostral-caudal axis of
             the SC with one being more caudal than the other, and 60
             neuron pairs whose movement fields were large enough to see
             a spread of activity were studied. During individual
             saccades, the relative time of discharge of the two neurons
             was compared using 1) the time difference between peak
             discharge of the two neurons, 2) the difference between the
             "median activation time" of the two neurons, and 3) the
             shift required to align the two discharge patterns using
             cross-correlation. All three analysis methods gave
             comparable results. Many pairs of neurons were activated in
             sequence during saccade generation, and the order of
             activation was most frequently caudal to rostral. Such a
             sequence of activation was not observed in every neuron
             pair, but over the sample of neuron pairs studied, the
             spread was statistically significant. When we compared the
             time of neuronal activity to the time of saccade onset, we
             found that the caudal neuronal activity was more likely to
             be before the saccade, whereas the rostral neuronal activity
             was more likely to be during the saccade. These results
             demonstrate that when individual pairs of neurons are
             examined during single saccades there is evidence of a
             caudal to rostral spread of activity within the monkey SC,
             and they confirm the previous inferences of a spread of
             activity drawn from observations on averaged neuronal
             activity during multiple saccades. The functional
             contribution of this spread of activity remains to be
             determined.},
   Doi = {10.1152/jn.2000.84.1.344},
   Key = {fds334849}
}

@article{Tehovnik2000,
   Author = {Tehovnik, EJ and Sommer, MA and Chou, IH and Slocum, WM and Schiller,
             PH},
   Title = {Eye fields in the frontal lobes of primates.},
   Journal = {Brain Research. Brain Research Reviews},
   Volume = {32},
   Number = {2-3},
   Pages = {413-448},
   Year = {2000},
   Month = {April},
   ISSN = {0165-0173},
   url = {https://dl.dropbox.com/u/27738651/Publications/TehovnikEtAl-2000_EyeFieldsInFrontalCortex-Review.pdf},
   Abstract = {Two eye fields have been identified in the frontal lobes of
             primates: one is situated dorsomedially within the frontal
             cortex and will be referred to as the eye field within the
             dorsomedial frontal cortex (DMFC); the other resides
             dorsolaterally within the frontal cortex and is commonly
             referred to as the frontal eye field (FEF). This review
             documents the similarities and differences between these eye
             fields. Although the DMFC and FEF are both active during the
             execution of saccadic and smooth pursuit eye movements, the
             FEF is more dedicated to these functions. Lesions of DMFC
             minimally affect the production of most types of saccadic
             eye movements and have no effect on the execution of smooth
             pursuit eye movements. In contrast, lesions of the FEF
             produce deficits in generating saccades to briefly presented
             targets, in the production of saccades to two or more
             sequentially presented targets, in the selection of
             simultaneously presented targets, and in the execution of
             smooth pursuit eye movements. For the most part, these
             deficits are prevalent in both monkeys and humans.
             Single-unit recording experiments have shown that the DMFC
             contains neurons that mediate both limb and eye movements,
             whereas the FEF seems to be involved in the execution of eye
             movements only. Imaging experiments conducted on humans have
             corroborated these findings. A feature that distinguishes
             the DMFC from the FEF is that the DMFC contains a
             somatotopic map with eyes represented rostrally and
             hindlimbs represented caudally; the FEF has no such
             topography. Furthermore, experiments have revealed that the
             DMFC tends to contain a craniotopic (i.e., head-centered)
             code for the execution of saccadic eye movements, whereas
             the FEF contains a retinotopic (i.e., eye-centered) code for
             the elicitation of saccades. Imaging and unit recording data
             suggest that the DMFC is more involved in the learning of
             new tasks than is the FEF. Also with continued training on
             behavioural tasks the responsivity of the DMFC tends to
             drop. Accordingly, the DMFC is more involved in learning
             operations whereas the FEF is more specialized for the
             execution of saccadic and smooth pursuit eye
             movements.},
   Doi = {10.1016/s0165-0173(99)00092-2},
   Key = {Tehovnik2000}
}

@article{fds334848,
   Author = {Sommer, MA and Wurtz, RH},
   Title = {Composition and topographic organization of signals sent
             from the frontal eye field to the superior
             colliculus.},
   Journal = {Journal of Neurophysiology},
   Volume = {83},
   Number = {4},
   Pages = {1979-2001},
   Year = {2000},
   Month = {April},
   url = {http://dx.doi.org/10.1152/jn.2000.83.4.1979},
   Abstract = {The frontal eye field (FEF) and superior colliculus (SC)
             contribute to saccadic eye movement generation, and much of
             the FEF's oculomotor influence may be mediated through the
             SC. The present study examined the composition and
             topographic organization of signals flowing from FEF to SC
             by recording from FEF neurons that were antidromically
             activated from rostral or caudal SC. The first and most
             general result was that, in a sample of 88 corticotectal
             neurons, the types of signals relayed from FEF to SC were
             highly diverse, reflecting the general population of signals
             within FEF rather than any specific subset of signals.
             Second, many neurons projecting from FEF to SC carried
             signals thought to reflect cognitive operations, namely
             tonic discharges during the delay period of a
             delayed-saccade task (delay signals), elevated discharges
             during the gap period of a gap task (gap increase signals),
             or both. Third, FEF neurons discharging during fixation were
             found to project to the SC, although they did not project
             preferentially to rostral SC, where similar fixation neurons
             are found. Neurons that did project preferentially to the
             rostral SC were those with foveal visual responses and those
             pausing during the gap period of the gap task. Many of the
             latter neurons also had foveal visual responses, presaccadic
             pauses in activity, and postsaccadic increases in activity.
             These two types of rostral-projecting neurons therefore may
             contribute to the activity of rostral SC fixation neurons.
             Fourth, conduction velocity was used as an indicator of cell
             size to correct for sampling bias. The outcome of this
             correction procedure suggested that among the most prevalent
             neurons in the FEF corticotectal population are those
             carrying putative cognitive-related signals, i.e., delay and
             gap increase signals, and among the least prevalent are
             those carrying presaccadic burst discharges but lacking
             peripheral visual responses. Fifth, corticotectal neurons
             carrying various signals were biased topographically across
             the FEF. Neurons with peripheral visual responses but
             lacking presaccadic burst discharges were biased laterally,
             neurons with presaccadic burst discharges but lacking
             peripheral visual responses were biased medially, and
             neurons carrying delay or gap increase signals were biased
             dorsally. Finally, corticotectal neurons were distributed
             within the FEF as a function of their visual or movement
             field eccentricity and projected to the SC such that
             eccentricity maps in both structures were closely aligned.
             We conclude that the FEF most likely influences the activity
             of SC neurons continuously from the start of fixation,
             through visual analysis and cognitive manipulations, until a
             saccade is generated and fixation begins anew. Furthermore,
             the projection from FEF to SC is highly topographically
             organized in terms of function at both its source and its
             termination.},
   Doi = {10.1152/jn.2000.83.4.1979},
   Key = {fds334848}
}

@article{Sommer1999,
   Author = {Sommer, MA and Tehovnik, EJ},
   Title = {Reversible inactivation of macaque dorsomedial frontal
             cortex: effects on saccades and fixations.},
   Journal = {Experimental Brain Research},
   Volume = {124},
   Number = {4},
   Pages = {429-446},
   Year = {1999},
   Month = {February},
   ISSN = {0014-4819},
   url = {https://dl.dropbox.com/u/27738651/Publications/SommerTehovnik1999-DMFCinactivation.pdf},
   Abstract = {Neural recording and electrical stimulation results suggest
             that the dorsomedial frontal cortex (DMFC) of macaque is
             involved in oculomotor behavior. We reversibly inactivated
             the DMFC using lidocaine and examined how saccadic eye
             movements and fixations were affected. The inactivation
             methods and monkeys were the same as those used in a
             previous study of the frontal eye field (FEF), another
             frontal oculomotor region. In the first stage of the present
             study, monkeys performed tasks that required the generation
             of single saccades and fixations. During 15 DMFC
             inactivations, we found only mild, infrequent deficits. This
             contrasts with our prior finding that FEF inactivation
             causes severe, reliable deficits in performance of these
             tasks. In the second stage of the study, we investigated
             whether DMFC inactivation affected behavior when a monkey
             was required to make more than one saccade and fixation. We
             used a double-step task: two targets were flashed in rapid
             succession and the monkey had to make two saccades to
             foveate the target locations. In each of five experiments,
             DMFC inactivation caused a moderate, significant deficit.
             Both ipsi- and contraversive saccades were disrupted. In two
             experiments, the first saccades were made to the wrong place
             and had increased latencies. In one experiment, first
             saccades were unaffected, but second saccades were made to
             the wrong place and had increased latencies. In the
             remaining two experiments, specific reasons for the deficit
             were not detected. Saline infusions into DMFC had no effect.
             Inactivation of FEF caused a larger double-step deficit than
             did inactivation of DMFC. The FEF inactivation impaired
             contraversive first or second saccades of the sequence. In
             conclusion, our results suggest that the DMFC makes an
             important contribution to generating sequential saccades and
             fixations but not single saccades and fixations. Compared
             with the FEF, the DMFC has a weaker, less directional, more
             task-dependent oculomotor influence.},
   Doi = {10.1007/s002210050639},
   Key = {Sommer1999}
}

@article{Chou1999,
   Author = {Chou, IH and Sommer, MA and Schiller, PH},
   Title = {Express averaging saccades in monkeys.},
   Journal = {Vision Research},
   Volume = {39},
   Number = {25},
   Pages = {4200-4216},
   Year = {1999},
   Month = {January},
   ISSN = {0042-6989},
   url = {https://dl.dropbox.com/u/27738651/Publications/ChouEtAl1999-ExpressAveragingSaccades.pdf},
   Abstract = {When monkeys are presented simultaneously with multiple
             stimuli, they can make one of two types of response. Either
             they make averaging saccades, that land at intermediate
             locations between the targets, or target-directed saccades,
             that land close to one of the targets. The two types of
             saccades occur at different latencies and are thought to
             reflect different processes; fast reflexive averaging and
             slower target selection. We investigated the latency of
             averaging saccades in five monkeys, with particular emphasis
             on 'express' latency saccades, which are thought to be
             inhibited by target selection. Express averaging saccades
             were made prolifically by the two monkeys that made both
             express and regular latency saccades, but only when no
             specific instruction was given regarding the saccade target.
             When these monkeys had to choose one of the targets, on the
             basis of its color, they still made averaging saccades.
             However, the endpoints formed two distributions close to the
             targets as opposed to one single distribution centered
             between the targets, as was the case when targets were
             identical; also, express saccades were almost entirely
             absent. We conclude that express averaging saccades are a
             form of spatial and temporal optimization of gaze
             shifting.},
   Doi = {10.1016/s0042-6989(99)00133-9},
   Key = {Chou1999}
}

@article{fds334853,
   Author = {Sommer, MA and Wurtz, RH},
   Title = {Frontal eye field neurons orthodromically activated from the
             superior colliculus.},
   Journal = {Journal of Neurophysiology},
   Volume = {80},
   Number = {6},
   Pages = {3331-3335},
   Year = {1998},
   Month = {December},
   url = {http://dx.doi.org/10.1152/jn.1998.80.6.3331},
   Abstract = {Frontal eye field neurons orthodromically activated from the
             superior colliculus. J. Neurophysiol. 80: 3331-3333, 1998.
             Anatomical studies have shown that the frontal eye field
             (FEF) and superior colliculus (SC) of monkeys are
             reciprocally connected, and a physiological study described
             the signals sent from the FEF to the SC. Nothing is known,
             however, about the signals sent from the SC to the FEF. We
             physiologically identified and characterized FEF neurons
             that are likely to receive input from the SC. Fifty-two FEF
             neurons were found that were orthodromically activated by
             electrical stimulation of the intermediate or deeper layers
             of the SC. All the neurons that we tested (n = 34)
             discharged in response to visual stimulation. One-half also
             discharged when saccadic eye movements were made. This
             provides the first direct evidence that the ascending
             pathway from SC to FEF might carry visual- and
             saccade-related signals. Our findings support a hypothesis
             that the SC and the FEF interact bidirectionally during the
             events leading up to saccade generation.},
   Doi = {10.1152/jn.1998.80.6.3331},
   Key = {fds334853}
}

@article{fds334852,
   Author = {Nichols, AM and Ruffner, TW and Sommer, MA and Wurtz,
             RH},
   Title = {A screw microdrive for adjustable chronic unit recording in
             monkeys.},
   Journal = {Journal of Neuroscience Methods},
   Volume = {81},
   Number = {1-2},
   Pages = {185-188},
   Year = {1998},
   Month = {June},
   ISSN = {0165-0270},
   url = {https://dl.dropbox.com/u/27738651/Publications/NicholsRuffnerSommerWurtz_JNeuroscienceMethods1998.pdf},
   Abstract = {A screw microdrive is described that attaches to the grid
             system used for recording single neurons from brains of
             awake behaving monkeys. Multiple screwdrives can be mounted
             on a grid over a single cranial opening. This method allows
             many electrodes to be implanted chronically in the brain and
             adjusted as needed to maintain isolation. rights
             reserved.},
   Doi = {10.1016/s0165-0270(98)00036-3},
   Key = {fds334852}
}

@article{Tehovnik1997a,
   Author = {Tehovnik, EJ and Sommer, MA},
   Title = {Electrically evoked saccades from the dorsomedial frontal
             cortex and frontal eye fields: a parametric evaluation
             reveals differences between areas.},
   Journal = {Experimental Brain Research},
   Volume = {117},
   Number = {3},
   Pages = {369-378},
   Year = {1997},
   Month = {December},
   ISSN = {0014-4819},
   url = {https://dl.dropbox.com/u/27738651/Publications/TehovnikSommer1997.pdf},
   Abstract = {Using electrical stimulation to evoke saccades from the
             dorsomedial frontal cortex (DMFC) and frontal eye fields
             (FEF) of rhesus monkeys, parametric tests were conducted to
             compare the excitability properties of these regions. Pulse
             frequency and pulse current, pulse frequency and train
             duration, and pulse current and pulse duration were varied
             to determine threshold functions for a 50% probability of
             evoking a saccade. Also a wide range of frequencies were
             tested to evoke saccades, while holding all other parameters
             constant. For frequencies beyond 150 Hz, the probability of
             evoking saccades decreased for the DMFC, whereas for the FEF
             this probability remained at 100%. To evoke saccades readily
             from the DMFC, train durations of greater than 200 ms were
             needed; for the FEF, durations of less than 100 ms were
             sufficient. Even though the chronaxies of neurons residing
             in the DMFC and FEF were similar (ranging from 0.1 to 0.24
             ms) significantly higher currents were required to evoke
             saccades from the DMFC than FEF. Thus the stimulation
             parameters that are optimal for evoking saccades from the
             DMFC differ from those that are optimal for evoking saccades
             from the FEF. Although the excitability of neurons in the
             DMFC and FEF are similar (due to similar chronaxies), we
             suggest that the density of saccade-relevant neurons is
             higher in the FEF than in the DMFC.},
   Doi = {10.1007/s002210050231},
   Key = {Tehovnik1997a}
}

@article{Sommer1997b,
   Author = {Sommer, MA},
   Title = {The spatial relationship between scanning saccades and
             express saccades.},
   Journal = {Vision Research},
   Volume = {37},
   Number = {19},
   Pages = {2745-2756},
   Year = {1997},
   Month = {October},
   ISSN = {0042-6989},
   url = {https://dl.dropbox.com/u/27738651/Publications/Sommer1997-ScanningAndExpressSaccades.pdf},
   Abstract = {When monkeys interrupt their saccadic scanning of a visual
             scene to look at a suddenly appearing target, saccades to
             the target are made after an "express" latency or after a
             longer "regular" latency. The purpose of this study was to
             analyze the spatial patterns of scanning, express, and
             regular saccades. Scanning patterns were spatially biased.
             Express saccade patterns were biased, too, and were directly
             correlated with scanning patterns. Regular saccade patterns
             were more uniform and were not directly correlated with
             scanning patterns. Express saccades, but not regular
             saccades, seemed to be facilitated by preparation to scan.
             This study contributes to a general understanding of how
             monkeys examine scenes containing both unchanging and
             suddenly appearing stimuli.},
   Doi = {10.1016/s0042-6989(97)00078-3},
   Key = {Sommer1997b}
}

@article{Sommer1997a,
   Author = {Sommer, MA and Tehovnik, EJ},
   Title = {Reversible inactivation of macaque frontal eye
             field.},
   Journal = {Experimental Brain Research},
   Volume = {116},
   Number = {2},
   Pages = {229-249},
   Year = {1997},
   Month = {September},
   ISSN = {0014-4819},
   url = {https://dl.dropbox.com/u/27738651/Publications/SommerTehovnik1997.pdf},
   Abstract = {The macaque frontal eye field (FEF) is involved in the
             generation of saccadic eye movements and fixations. To
             better understand the role of the FEF, we reversibly
             inactivated a portion of it while a monkey made saccades and
             fixations in response to visual stimuli. Lidocaine was
             infused into a FEF and neural inactivation was monitored
             with a nearby microelectrode. We used two saccadic tasks. In
             the delay task, a target was presented and then
             extinguished, but the monkey was not allowed to make a
             saccade to its location until a cue to move was given. In
             the step task, the monkey was allowed to look at a target as
             soon as it appeared. During FEF inactivation, monkeys were
             severely impaired at making saccades to locations of
             extinguished contralateral targets in the delay task. They
             were similarly impaired at making saccades to locations of
             contralateral targets in the step task if the target was
             flashed for < or =100 ms, such that it was gone before the
             saccade was initiated. Deficits included increases in
             saccadic latency, increases in saccadic error, and increases
             in the frequency of trials in which a saccade was not made.
             We varied the initial fixation location and found that the
             impairment specifically affected contraversive saccades
             rather than affecting all saccades made into head-centered
             contralateral space. Monkeys were impaired only slightly at
             making saccades to contralateral targets in the step task if
             the target duration was 1000 ms, such that the target was
             present during the saccade: latency increased, but increases
             in saccadic error were mild and increases in the frequency
             of trials in which a saccade was not made were
             insignificant. During FEF inactivation there usually was a
             direct correlation between the latency and the error of
             saccades made in response to contralateral targets. In the
             delay task, FEF inactivation increased the frequency of
             making premature saccades to ipsilateral targets. FEF
             inactivation had inconsistent and mild effects on saccadic
             peak velocity. FEF inactivation caused impairments in the
             ability to fixate lights steadily in contralateral space.
             FEF inactivation always caused an ipsiversive deviation of
             the eyes in darkness. In summary, our results suggest that
             the FEF plays major roles in (1) generating contraversive
             saccades to locations of extinguished or flashed targets,
             (2) maintaining contralateral fixations, and (3) suppressing
             inappropriate ipsiversive saccades.},
   Doi = {10.1007/pl00005752},
   Key = {Sommer1997a}
}

@article{Tehovnik1997b,
   Author = {Tehovnik, EJ and Sommer, MA},
   Title = {Effective spread and timecourse of neural inactivation
             caused by lidocaine injection in monkey cerebral
             cortex.},
   Journal = {Journal of Neuroscience Methods},
   Volume = {74},
   Number = {1},
   Pages = {17-26},
   Year = {1997},
   Month = {June},
   ISSN = {0165-0270},
   url = {https://dl.dropbox.com/u/27738651/Publications/TehovnikSommer1997-LidocaineInactivation.pdf},
   Abstract = {We studied the effective spread of lidocaine to inactivate
             neural tissue in the frontal cortex of the rhesus monkey.
             Injections of 2% lidocaine at 4 microl/min were made while
             units were recorded 1 or 2 mm away. To inactivate units 1 mm
             away from the injection site 100% of the time, 7 microl of
             lidocaine had to be injected. To inactivate units 2 mm away
             from the injection site 100% of the time, 30 microl of
             lidocaine were required. Units were maximally inactivated
             around 8 min after the start of a lidocaine injection, and
             they gradually recovered, regaining most of their initial
             activity by around 30 min after the start of an injection.
             The volume of lidocaine required to inactivate neurons > 90%
             of the time could be estimated by the spherical volume
             equation, V = 4/3 pi (r)3. To prolong the inactivation, a
             slower infusion of lidocaine subsequent to an initial bolus
             was effective. Saline control injections had no effect.
             These results allow both a prediction of the timecourse of
             neural inactivation and an estimate of the spread of neural
             inactivation following injection of lidocaine into the
             monkey cerebral cortex.},
   Doi = {10.1016/s0165-0270(97)02229-2},
   Key = {Tehovnik1997b}
}

@article{Tehovnik1996,
   Author = {Tehovnik, EJ and Sommer, MA},
   Title = {Compensatory saccades made to remembered targets following
             orbital displacement by electrically stimulating the
             dorsomedial frontal cortex or frontal eye fields of
             primates.},
   Journal = {Brain Research},
   Volume = {727},
   Number = {1-2},
   Pages = {221-224},
   Year = {1996},
   Month = {July},
   ISSN = {0006-8993},
   url = {https://dl.dropbox.com/u/27738651/Publications/TehovnikSommer1996.pdf},
   Abstract = {If the eye-position signal during visually-evoked saccades
             is dependent on the dorsomedial frontal cortex (DMFC), one
             would expect that saccades generated to briefly presented
             visual targets would be disrupted after displacement of the
             eyes via electrical stimulation of this cortical area.
             Compared are compensatory saccades evoked to brief targets
             following stimulation of the DMFC and frontal eye fields
             (FEF). Compensatory saccades produced to brief targets
             following perturbation via the DMFC were not affected.
             Accordingly, electrical stimulation of the DMFC does not
             disrupt the eye-position signal during the execution of
             visually-evoked saccades.},
   Doi = {10.1016/0006-8993(96)00475-1},
   Key = {Tehovnik1996}
}

@article{SOMMER1994,
   Author = {Sommer, MA},
   Title = {Express saccades elicited during visual scan in the
             monkey.},
   Journal = {Vision Research},
   Volume = {34},
   Number = {15},
   Pages = {2023-2038},
   Year = {1994},
   Month = {August},
   ISSN = {0042-6989},
   url = {https://dl.dropbox.com/u/27738651/Publications/Sommer1994.pdf},
   Abstract = {Monkeys trained to saccade to visual targets can develop
             separate "express" and "regular" modes in their distribution
             of saccadic latencies. The purpose of this study was to
             determine whether this occurs under more natural viewing
             conditions, when targets are suddenly presented in a
             structured visual field during visual scan. It was found
             that scanning saccades stopped appearing 60 msec after a
             target's onset, and subsequent saccades, which were directed
             toward the suddenly appearing target, had a bimodal
             distribution of latencies. Express saccades were more likely
             to occur as the target was presented later in a fixation.
             Regular mode saccades were more likely to occur with longer
             target durations. Scanning saccades made to stimuli of the
             structured visual field always had unimodal inter-saccadic
             interval distributions. All these effects were apparent
             after only 2-3 days of training. These findings, taken
             together with recent physiological results, suggest that the
             visuomotor cells of the superior colliculus mediate latency
             bimodality.},
   Doi = {10.1016/0042-6989(94)90030-2},
   Key = {SOMMER1994}
}

@article{RICHARDS1994,
   Author = {Richards, W and Wilson, HR and Sommer, MA},
   Title = {Chaos in percepts?},
   Journal = {Biological Cybernetics},
   Volume = {70},
   Number = {4},
   Pages = {345-349},
   Year = {1994},
   Month = {January},
   ISSN = {0340-1200},
   url = {https://dl.dropbox.com/u/27738651/Publications/RichardsWilsonSommer1994_BiologicalCybernetics.pdf},
   Abstract = {Multistability in perceptual tasks has suggested that the
             mechanisms underlying our percepts might be modeled as
             nonlinear, deterministic systems that exhibit chaotic
             behavior. We present evidence supporting this view,
             obtaining an estimate of 3.5 for the dimensionality of such
             a system. A surprising result is that this estimate applies
             for a rather diverse range of perceptual
             tasks.},
   Doi = {10.1007/bf00200331},
   Key = {RICHARDS1994}
}

@article{fds334862,
   Author = {Sommer, MA and Schiller, PH and McPeek, RM},
   Title = {What neural pathways mediate express saccades?},
   Journal = {Behavioral and Brain Sciences},
   Volume = {16},
   Number = {3},
   Pages = {589-590},
   Publisher = {Cambridge University Press (CUP): STM Journals},
   Year = {1993},
   Month = {September},
   url = {http://dx.doi.org/10.1017/S0140525X00031824},
   Doi = {10.1017/S0140525X00031824},
   Key = {fds334862}
}

@article{fds334863,
   Author = {Sommer, MA and Forno, LS and Smith, ME},
   Title = {EAE cerebrospinal fluid augments in vitro phagocytosis and
             metabolism of CNS myelin by macrophages.},
   Journal = {Journal of Neuroscience Research},
   Volume = {32},
   Number = {3},
   Pages = {384-394},
   Year = {1992},
   Month = {July},
   ISSN = {1097-4547},
   url = {https://dl.dropbox.com/u/27738651/Publications/SommerFornoSmith_JNeurosciRes1992.pdf},
   Abstract = {Previous studies from this laboratory have shown that CNS
             myelin is phagocytized and metabolized by cultured rat
             macrophages to a much larger extent when myelin is
             pretreated with serum containing antibodies to myelin
             constituents than when it is left untreated or pretreated
             with non-specific serum. In this study the effect of
             cerebrospinal fluid (CSF) from rabbits with experimental
             allergic encephalomyelitis (EAE) in promoting myelin
             phagocytosis was examined. Fourteen rabbits were immunized
             with purified myelin in Freund's complete adjuvant, seven of
             which developed clinical EAE symptoms. Serum and CSF were
             collected from EAE and control rabbits, and the CSF was
             centrifuged to remove cells. Sera and CSF from these rabbits
             and from Freund's adjuvant-immunized controls and untreated
             controls were measured for IgG content by radial diffusion
             assay, their myelin antibody characteristics were analyzed
             by immunoblots, and the ability of these serum and CSF
             samples to promote myelin phagocytosis when used for myelin
             opsonization was examined. The ability of a CSF sample to
             enhance radioactive myelin uptake and phagocytosis by
             cultured macrophages as measured by the appearance of
             radioactive cholesterol ester was linearly proportional to
             its total IgG titer, and correlated approximately both with
             clinical symptoms of the animal and the presence of antibody
             against the myelin constituents myelin basic protein,
             proteolipid protein, and galactocerebroside. The cholesterol
             esterification activities of EAE sera correlated to a lesser
             extent with IgG levels and clinical symptoms.(ABSTRACT
             TRUNCATED AT 250 WORDS)},
   Doi = {10.1002/jnr.490320310},
   Key = {fds334863}
}

@article{fds334864,
   Author = {Smith, ME and Sommer, MA},
   Title = {Association between cell-mediated demyelination and
             astrocyte stimulation.},
   Journal = {Progress in Brain Research},
   Volume = {94},
   Pages = {411-422},
   Year = {1992},
   Month = {January},
   url = {http://dx.doi.org/10.1016/s0079-6123(08)61768-9},
   Doi = {10.1016/s0079-6123(08)61768-9},
   Key = {fds334864}
}

@article{fds334866,
   Author = {Sadler, RH and Sommer, MA and Forno, LS and Smith,
             ME},
   Title = {Induction of anti-myelin antibodies in EAE and their
             possible role in demyelination.},
   Journal = {Journal of Neuroscience Research},
   Volume = {30},
   Number = {4},
   Pages = {616-624},
   Year = {1991},
   Month = {December},
   ISSN = {1097-4547},
   url = {https://dl.dropbox.com/u/27738651/Publications/SadlerSommerFornoSmith_JNeurosciRes1991.pdf},
   Abstract = {Experimental allergic encephalomyelitis is characterized by
             invasion of lymphocytes and macrophages into the central
             nervous system resulting in inflammation, edema, and
             demyelination. Sera from Lewis rats from 7-95 days after
             immunization with purified guinea pig CNS myelin were
             examined with respect to their ability to opsonize myelin.
             This was correlated with the appearance of antibody
             components and the relative amounts of antibody to myelin
             basic protein (MBP) and proteolipid protein (PLP). Sera from
             rats 10-95 days after immunization preincubated with
             purified myelin induced phagocytosis of myelin by cultured
             macrophages with the resulting production of cholesterol
             ester. This opsonization activity as measured by the
             percentage of cholesterol esterified reached a peak at 26-27
             days after immunization but remained significantly elevated
             up to 95 days post-immunization compared to the activity of
             serum from the Freund's adjuvant-injected controls.
             Immunoblots of the sera revealed a gradual increase in
             antibody activity against myelin components. ELISA assays
             for MBP and PLP antibody showed a similar pattern. Antibody
             to galactocerebroside (GC) was not detected by immunostains
             nor by the ELISA assay. Areas of demyelination were observed
             histologically by luxol-fast blue stained spinal cords up to
             60 days post-immunization. These results indicate that
             antibodies to myelin protein when given access to myelin
             through or within the blood brain barrier could initiate or
             enhance the phagocytic response by peripheral or resident
             macrophages.},
   Doi = {10.1002/jnr.490300404},
   Key = {fds334866}
}

@article{fds334865,
   Author = {Hrushesky, WJ and Fader, DJ and Berestka, JS and Sommer, M and Hayes, J and Cope, FO},
   Title = {Diminishment of respiratory sinus arrhythmia foreshadows
             doxorubicin-induced cardiomyopathy.},
   Journal = {Circulation},
   Volume = {84},
   Number = {2},
   Pages = {697-707},
   Year = {1991},
   Month = {August},
   ISSN = {00097322},
   url = {https://dl.dropbox.com/u/27738651/Publications/HrusheskyFaderBerestkaSommerHayesCope_Circulation1991.pdf},
   Abstract = {BACKGROUND:The development of a microcomputer-based device
             permits quick, simple, and noninvasive quantification of the
             respiratory sinus arrhythmia (RSA) during quiet breathing.
             METHODS AND RESULTS:We prospectively and serially measured
             the radionuclide left ventricular ejection fraction and the
             RSA amplitude in 34 cancer patients receiving up to nine
             monthly bolus treatments with doxorubicin hydrochloride (60
             mg/m2). Of the eight patients who ultimately developed
             symptomatic doxorubicin-induced congestive heart failure,
             seven (87.5%) demonstrated a significant decline in RSA
             amplitude; five of 26 subjects without clinical symptoms of
             cardiotoxicity (19.2%) showed a similar RSA amplitude
             decline. On average, significant RSA amplitude decline
             occurred 3 months before the last planned doxorubicin dose
             in patients destined to develop clinical congestive heart
             failure. CONCLUSION:Overall, RSA amplitude abnormality
             proved to be a more specific predictor of clinically
             significant congestive heart failure than did serial resting
             radionuclide ejection fractions.},
   Doi = {10.1161/01.cir.84.2.697},
   Key = {fds334865}
}

@article{fds334867,
   Author = {Sommer Marc and A and Berestka John and B},
   Title = {RSA -- Respiratory Sinus Arrhythmia: A new measure of
             cardiac health},
   Journal = {Medical Electronics},
   Pages = {112-114},
   Year = {1987},
   Month = {April},
   ISSN = {0149-9734},
   url = {https://dl.dropbox.com/u/27738651/Publications/SommerBerestka_MedElectronics1987.pdf},
   Key = {fds334867}
}


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