Scholars@Duke
Marc A. Sommer

Marc A. Sommer

Professor of Biomedical Engineering
Biomedical Engineering
marc.sommer@duke.edu
Duke Box 90281, Durham, NC 27708-0281
1427 CIEMAS, Box 90281, 101 Science Dr., Durham, NC 27708

Selected Publications

A semi-automated pipeline for finite element modeling of electric field induced in nonhuman primates by transcranial magnetic stimulation.

Journal Article J Neurosci Methods · August 2024 BACKGROUND: Transcranial magnetic stimulation (TMS) is used to treat a range of brain disorders by inducing an electric field (E-field) in the brain. However, the precise neural effects of TMS are not well understood. Nonhuman primates (NHPs) are used to m ... Full text Link to item Cite

Bayesian and Discriminative Models for Active Visual Perception across Saccades.

Journal Article eNeuro · July 2023 The brain interprets sensory inputs to guide behavior, but behavior itself disrupts sensory inputs. Perceiving a coherent world while acting in it constitutes active perception. For example, saccadic eye movements displace visual images on the retina and y ... Full text Link to item Cite

Direct Comparison of Epifluorescence and Immunostaining for Assessing Viral Mediated Gene Expression in the Primate Brain.

Journal Article Human gene therapy · March 2023 Viral vector technologies are commonly used in neuroscience research to understand and manipulate neural circuits, but successful applications of these technologies in non-human primate models have been inconsistent. An essential component to improve these ... Full text Cite

Isolating two sources of variability of subcortical stimulation to quantify fluctuations of corticospinal tract excitability.

Journal Article Clin Neurophysiol · June 2022 OBJECTIVE: Investigate the variability previously found with cortical stimulation and handheld transcranial magnetic stimulation (TMS) coils, criticized for its high potential of coil position fluctuations, bypassing the cortex using deep brain electrical ... Full text Link to item Cite

Compensating for a shifting world: evolving reference frames of visual and auditory signals across three multimodal brain areas.

Journal Article Journal of neurophysiology · July 2021 Stimulus locations are detected differently by different sensory systems, but ultimately they yield similar percepts and behavioral responses. How the brain transcends initial differences to compute similar codes is unclear. We quantitatively compared the ... Full text Cite

Psychophysiological Markers of Performance and Learning during Simulated Marksmanship in Immersive Virtual Reality.

Journal Article J Cogn Neurosci · June 1, 2021 The fusion of immersive virtual reality, kinematic movement tracking, and EEG offers a powerful test bed for naturalistic neuroscience research. Here, we combined these elements to investigate the neuro-behavioral mechanisms underlying precision visual-mot ... Full text Link to item Cite

An Open Resource for Non-human Primate Optogenetics.

Journal Article Neuron · December 23, 2020 Optogenetics has revolutionized neuroscience in small laboratory animals, but its effect on animal models more closely related to humans, such as non-human primates (NHPs), has been mixed. To make evidence-based decisions in primate optogenetics, the scien ... Full text Link to item Cite

Using rAAV2-retro in rhesus macaques: Promise and caveats for circuit manipulation.

Journal Article Journal of neuroscience methods · November 2020 BackgroundRecent genetic technologies such as opto- and chemogenetics allow for the manipulation of brain circuits with unprecedented precision. Most studies employing these techniques have been undertaken in rodents, but a more human-homologous m ... Full text Cite

Adeno-Associated Virus Capsid-Promoter Interactions in the Brain Translate from Rat to the Nonhuman Primate.

Journal Article Human gene therapy · November 2020 Recently, we established an adeno-associated virus (AAV9) capsid-promoter interaction that directly determined cell-specific gene expression across two synthetic promoters, Cbh and CBA, in the rat striatum. These studies not only expand this capsid-promote ... Full text Cite

Intensity- and timing-dependent modulation of motion perception with transcranial magnetic stimulation of visual cortex.

Journal Article Neuropsychologia · October 2020 Despite the widespread use of transcranial magnetic stimulation (TMS) in research and clinical care, the dose-response relations and neurophysiological correlates of modulatory effects remain relatively unexplored. To fill this gap, we studied modulation o ... Full text Open Access Link to item Cite

Application of long-interval paired-pulse transcranial magnetic stimulation to motion-sensitive visual cortex does not lead to changes in motion discrimination.

Journal Article Neurosci Lett · June 21, 2020 The perception of visual motion is dependent on a set of occipitotemporal regions that are readily accessible to neuromodulation. The current study tested if paired-pulse Transcranial Magnetic Stimulation (ppTMS) could modulate motion perception by stimula ... Full text Open Access Link to item Cite

Mapping Motor Cortex Stimulation to Muscle Responses: A Deep Neural Network Modeling Approach.

Conference The ... International Conference on PErvasive Technologies Related to Assistive Environments : PETRA ... International Conference on PErvasive Technologies Related to Assistive Environments · June 2020 A deep neural network (DNN) that can reliably model muscle responses from corresponding brain stimulation has the potential to increase knowledge of coordinated motor control for numerous basic science and applied use cases. Such cases include the understa ... Full text Cite

Dose-dependent enhancement of motion direction discrimination with transcranial magnetic stimulation of visual cortex

Journal Article · 2020 Despite the widespread use of transcranial magnetic stimulation (TMS) in research and clinical care, the underlying mechanisms-of-actions that mediate modulatory effects remain poorly understood. To fill this gap, we studied dose–response functions of TMS ... Full text Cite

Properties of decision-making tasks govern the tradeoff between model-based and model-free learning

Journal Article · August 14, 2019 AbstractWhen decisions must be made between uncertain options, optimal behavior depends on accurate estimations of the likelihoods of different outcomes. The contextual factors that govern whether these estimations depend o ... Full text Open Access Cite

Probabilistic inferential decision-making under time pressure in rhesus macaques (Macaca mulatta).

Journal Article Journal of comparative psychology (Washington, D.C. : 1983) · August 2019 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. ... Full text Open Access Cite

Compensating for a shifting world: evolving reference frames of visual and auditory signals across three multimodal brain areas

Journal Article · June 13, 2019 ABSTRACTStimulus locations are detected differently by different sensory systems, but ultimately they yield similar percepts and behavioral responses. How the brain transcends initial differences to compute similar codes is ... Full text Cite

Corollary discharge for action and cognition

Journal Article Biological Psychiatry: Cognitive Neuroscience and Neuroimaging · May 30, 2019 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 reveali ... Full text Open Access Cite

An experimental and computational framework for modeling multi-muscle responses to transcranial magnetic stimulation of the human motor cortex

Conference International IEEE/EMBS Conference on Neural Engineering, NER · May 16, 2019 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 k ... Full text Open Access Cite

Neurophysiology of Visual-Motor Learning during a Simulated Marksmanship Task in Immersive Virtual Reality

Conference 25th IEEE Conference on Virtual Reality and 3D User Interfaces, VR 2018 - Proceedings · August 24, 2018 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 techni ... Full text Open Access Cite

Neuronal correlates of serial decision-making in the supplementary eye field

Journal Article Journal of Neuroscience · August 15, 2018 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), whic ... Open Access Cite

Sensorimotor Learning during a Marksmanship Task in Immersive Virtual Reality.

Journal Article Front Psychol · 2018 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 med ... Full text Open Access Link to item Cite

Serial decision-making in monkeys during an oculomotor task

Journal Article Journal of Experimental Psychology: Animal Learning and Cognition · January 2018 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 acros ... Full text Open Access Cite

Beyond the labeled line: variation in visual reference frames from intraparietal cortex to frontal eye fields and the superior colliculus

Journal Article Journal of Neurophysiology · December 20, 2017 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 ... Full text Open Access Cite

Probabilistic inference under time pressure leads to a cortical-to-subcortical shift in decision evidence integration

Journal Article NeuroImage · November 15, 2017 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 ... Full text Open Access Cite

Supplementary Eye Fields

Chapter · 2017 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 ... Open Access Cite

Satisficing in split-second decision making is characterized by strategic cue discounting

Journal Article Journal of Experimental Psychology: Learning, Memory, and Cognition · December 2016 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- ... Full text Open Access Cite

Circuits for presaccadic visual remapping.

Journal Article J Neurophysiol · December 1, 2016 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 rema ... Full text Open Access Link to item Cite

Neural network evidence for the coupling of presaccadic visual remapping to predictive eye position updating

Journal Article Frontiers in Computational Neuroscience · June 2, 2016 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 ... Full text Open Access Cite

Contribution of cerebellar loops to action timing

Journal Article Current Opinion in Behavioral Sciences · March 9, 2016 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 common ... Full text Open Access Cite

Similar prevalence and magnitude of auditory-evoked and visually-evoked activity in the frontal eye fields: Implications for multisensory motor control

Journal Article Journal of Neurophysiology · March 2, 2016 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 preval ... Full text Open Access Cite

Visual continuity across saccades is influenced by expectations.

Journal Article Journal of vision · January 2016 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) a ... Full text Open Access Cite

Dynamics of visual receptive fields in the macaque frontal eye field.

Journal Article J Neurophysiol · December 2015 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 a ... Full text Open Access Link to item Cite

Exploring the Effects of Image Persistence in Low Frame Rate Virtual Environments

Journal Article Proceedings of the IEEE Virtual Reality Conference · 2015 Open Access Cite

Subjective duration as a signature of coding efficiency: Emerging links among stimulus repetition, predictive coding, and cortical GABA levels

Journal Article Timing & Time Perception Reviews · December 1, 2014 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 expecte ... Open Access Cite

Advances in understanding mechanisms of thalamic relays in cognition and behavior.

Journal Article The Journal of neuroscience : the official journal of the Society for Neuroscience · November 2014 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 beh ... Full text Open Access Cite

Simultaneous transcranial magnetic stimulation and single-neuron recording in alert non-human primates.

Journal Article Nat Neurosci · August 2014 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 ... Full text Open Access Link to item Cite

Cognitive control of movement via the cerebellar-recipient thalamus.

Journal Article Frontiers in systems neuroscience · October 2013 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 ci ... Full text Open Access Cite

Delay activity of saccade-related neurons in the caudal dentate nucleus of the macaque cerebellum.

Journal Article Journal of neurophysiology · April 2013 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 a ... Full text Open Access Cite

Spatial and temporal scales of neuronal correlation in visual area V4.

Journal Article The Journal of neuroscience : the official journal of the Society for Neuroscience · March 2013 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 coinc ... Full text Open Access Cite

Neuronal correlates of visual time perception at brief timescales.

Journal Article Proc Natl Acad Sci U S A · January 22, 2013 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 fid ... Full text Open Access Link to item Cite

Division of labor in frontal eye field neurons during presaccadic remapping of visual receptive fields.

Journal Article Journal of neurophysiology · October 2012 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 us ... Full text Open Access Cite

Neuronal correlates of metacognition in primate frontal cortex.

Journal Article Neuron · August 2012 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 prim ... Full text Open Access Cite

Frontal eye field neurons assess visual stability across saccades.

Journal Article The Journal of neuroscience : the official journal of the Society for Neuroscience · February 2012 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 wh ... Full text Open Access Cite

Exploring the role of the substantia nigra pars reticulata in eye movements.

Journal Article Neuroscience · December 2011 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 t ... Full text Open Access Cite

Metacognition in monkeys during an oculomotor task.

Journal Article Journal of experimental psychology. Learning, memory, and cognition · March 2011 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 m ... Full text Open Access Cite

Shifting attention to neurons.

Journal Article Trends Cogn Sci · September 2010 Full text Open Access Link to item Cite

Activity of neurons in monkey globus pallidus during oculomotor behavior compared with that in substantia nigra pars reticulata.

Journal Article Journal of neurophysiology · April 2010 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 pallidu ... Full text Open Access Cite

How the visual system monitors where the eyes will move

Journal Article Journal of Vision · December 1, 2009 Full text Open Access Cite

Frontal eye field neurons with spatial representations predicted by their subcortical input.

Journal Article The Journal of neuroscience : the official journal of the Society for Neuroscience · April 2009 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 a ... Full text Open Access Cite

Supplementary eye fields

Chapter · 2009 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 a ... Full text Open Access Cite

Corollary discharge circuits in the primate brain.

Journal Article Current opinion in neurobiology · December 2008 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 n ... Full text Open Access Cite

Neuronal adaptation caused by sequential visual stimulation in the frontal eye field.

Journal Article J Neurophysiol · October 2008 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 ho ... Full text Open Access Link to item Cite

Corollary discharge across the animal kingdom.

Journal Article Nature reviews. Neuroscience · August 2008 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 criti ... Full text Open Access Cite

Neuronal adaptation: Delay compensation at the level of single neurons?

Journal Article Behavioral and Brain Sciences · April 1, 2008 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 respo ... Full text Open Access Cite

Brain circuits for the internal monitoring of movements.

Journal Article Annual review of neuroscience · January 2008 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 conside ... Full text Open Access Cite

Visual perception and corollary discharge.

Journal Article Perception · January 2008 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 hypot ... Full text Open Access Cite

The frontal eye field as a prediction map.

Journal Article Progress in brain research · January 2008 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 de ... Full text Open Access Cite

Microcircuits for attention.

Journal Article Neuron · July 2007 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, ... Full text Open Access Cite

The feeling of looking.

Journal Article Nature neuroscience · May 2007 Full text Open Access Cite

Influence of the thalamus on spatial visual processing in frontal cortex.

Journal Article Nature · November 2006 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 ... Full text Open Access Cite

A corollary discharge for perceptual stability

Journal Article PERCEPTION · January 1, 2006 Open Access Link to item Cite

Drivers from the deep: the contribution of collicular input to thalamocortical processing.

Journal Article Progress in brain research · January 2005 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 ... Full text Open Access Cite

What the brain stem tells the frontal cortex. II. Role of the SC-MD-FEF pathway in corollary discharge.

Journal Article Journal of neurophysiology · March 2004 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) carr ... Full text Open Access Cite

What the brain stem tells the frontal cortex. I. Oculomotor signals sent from superior colliculus to frontal eye field via mediodorsal thalamus.

Journal Article Journal of neurophysiology · March 2004 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 sign ... Full text Open Access Cite

Identifying corollary discharges for movement in the primate brain.

Journal Article Progress in brain research · January 2004 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 ... Full text Open Access Cite

The role of the thalamus in motor control.

Journal Article Current opinion in neurobiology · December 2003 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 neurophys ... Full text Open Access Cite

The frontal eye field sends predictively remapped visual signals to the superior colliculus

Journal Article Journal of Vision · 2003 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 move ... Full text Open Access Cite

A pathway in primate brain for internal monitoring of movements.

Journal Article Science (New York, N.Y.) · May 2002 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 car ... Full text Open Access Cite

Frontal eye field sends delay activity related to movement, memory, and vision to the superior colliculus.

Journal Article Journal of neurophysiology · April 2001 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 ... Full text Open Access Cite

Signal transformations from cerebral cortex to superior colliculus for the generation of saccades.

Journal Article Vision research · January 2001 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 n ... Full text Open Access Cite

A subcortical source of visual input to the frontal eye field

Journal Article Journal of Vision · 2001 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 reas ... Full text Open Access Cite

Multielectrode evidence for spreading activity across the superior colliculus movement map.

Journal Article Journal of neurophysiology · July 2000 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 t ... Full text Open Access Cite

Eye fields in the frontal lobes of primates.

Journal Article Brain research. Brain research reviews · April 2000 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 ... Full text Open Access Cite

Composition and topographic organization of signals sent from the frontal eye field to the superior colliculus.

Journal Article Journal of neurophysiology · April 2000 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 s ... Full text Open Access Cite

Reversible inactivation of macaque dorsomedial frontal cortex: effects on saccades and fixations.

Journal Article Experimental brain research · February 1999 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 w ... Full text Open Access Cite

Express averaging saccades in monkeys.

Journal Article Vision research · January 1999 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 o ... Full text Open Access Cite

Frontal eye field neurons orthodromically activated from the superior colliculus.

Journal Article Journal of neurophysiology · December 1998 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 ... Full text Open Access Cite

A screw microdrive for adjustable chronic unit recording in monkeys.

Journal Article Journal of neuroscience methods · June 1998 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 ... Full text Open Access Cite

Electrically evoked saccades from the dorsomedial frontal cortex and frontal eye fields: a parametric evaluation reveals differences between areas.

Journal Article Experimental brain research · December 1997 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 cur ... Full text Open Access Cite

The spatial relationship between scanning saccades and express saccades.

Journal Article Vision research · October 1997 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 pa ... Full text Open Access Cite

Reversible inactivation of macaque frontal eye field.

Journal Article Experimental brain research · September 1997 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 ... Full text Open Access Cite

Effective spread and timecourse of neural inactivation caused by lidocaine injection in monkey cerebral cortex.

Journal Article Journal of neuroscience methods · June 1997 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 injec ... Full text Open Access Cite

Compensatory saccades made to remembered targets following orbital displacement by electrically stimulating the dorsomedial frontal cortex or frontal eye fields of primates.

Journal Article Brain research · July 1996 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 ... Full text Open Access Cite

Express saccades elicited during visual scan in the monkey.

Journal Article Vision research · August 1994 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 ... Full text Open Access Cite

Chaos in percepts?

Journal Article Biological cybernetics · January 1994 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 ... Full text Open Access Cite

What neural pathways mediate express saccades?

Journal Article Behavioral and Brain Sciences · September 1993 Full text Open Access Link to item Cite

EAE cerebrospinal fluid augments in vitro phagocytosis and metabolism of CNS myelin by macrophages.

Journal Article Journal of neuroscience research · July 1992 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 untr ... Full text Open Access Cite

Induction of anti-myelin antibodies in EAE and their possible role in demyelination.

Journal Article Journal of neuroscience research · December 1991 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 gu ... Full text Open Access Cite

Diminishment of respiratory sinus arrhythmia foreshadows doxorubicin-induced cardiomyopathy.

Journal Article Circulation · August 1991 BackgroundThe development of a microcomputer-based device permits quick, simple, and noninvasive quantification of the respiratory sinus arrhythmia (RSA) during quiet breathing.Methods and resultsWe prospectively and serially measured the ... Full text Open Access Cite

Transduction of Craniofacial Motoneurons Following Intramuscular Injections of Canine Adenovirus Type-2 (CAV-2) in Rhesus Macaques

Journal Article Frontiers in Neuroanatomy Reliable viral vector-mediated transgene expression in primate motoneurons would improve our ability to anatomically and physiologically interrogate motor systems. We therefore investigated the efficacy of replication defective, early region 1-deleted cani ... Full text Open Access Cite