Michael A. Silver, PhD Assistant Professor of Vision Science, Optometry and Neuroscience E-mail: masilver@berkeley.edu Web Site: Laboratory VS Web: Vision Science Page NS Web: Neuroscience Page

Teaching

Vision Science 206D. Neuroanatomy and Neurophysiology of the Eye and Visual System

Co-Instructor
Structure and function of the neurosensory retina, photoreceptors, RPE including blood supply. Current concepts of etiology and management of major retinal conditions. Overview of diagnostic techniques in retinal imaging, electrophysiologic testing and new genetic approaches. Structure and function of the early visual pathway including retinal ganglion cells, optic nerves, lateral geniculate nucleus and visual cortex. Pupillary responses. Specialization in the visual cortex.

Vision Science 212B. Visual Neurophysiology and Development

Co-Instructor
Introduction for graduate students. Visual pathways will be considered from retina to lateral geniculate to visual cortex. Basic organization at each stage will be covered. Primary focus will be studies of receptive field characteristics and associated visual function. Development and plasticity of the same visual pathways will also be covered. Evidence and implications will be explored from controlled rearing procedures and studies of abnormal visual exposure.

Vision Science 300. Teaching Methods in Vision Science

Instructor-in-Charge
Instruction in teaching methods and materials, in vision science and optometry, observation of classes in session; practice teaching in classrooms and laboratory.

Neural correlates of human visual perception and attention

When attention is allocated to a particular portion of the visual field, visual perception is enhanced at that location. This is thought to occur as a result of top-down attention signals that influence the processing of visual stimuli in occipital cortical areas. We use a combination of behavioral, neuroimaging, electrophysiological, modeling, and pharmacological techniques to characterize the neural pathways involved in the control of visual attention in humans and the effects of selective attention on processing of visual stimuli.

We have discovered two cortical areas in the human parietal lobe, IPS1 and IPS2, that contain topographic maps of spatial attention and may transmit retinotopically-specific top-down signals to early visual cortex. We are currently characterizing the functional interactions between IPS1/IPS2 and occipital visual areas. Pharmacological studies in the lab have focused on the cholinergic projection from the basal forebrain to the cerebral cortex. We have found that increasing synaptic acetylcholine levels enhances top-down spatial attention as measured behaviorally, increases the magnitude of neural (fMRI) correlates of attention in the superior parietal lobule and frontal eye fields, and reduces the spatial spread of visual responses in early visual cortex. Further pharmacological studies will determine the relationship between the effects of top-down attention signals and acetylcholine release on visual perception and on information processing in visual cortex. We are also studying the neural substrates of perceptual learning and the modulation of perceptual learning by cholinergic enhancement.

Another focus of the lab is binocular rivalry, a phenomenon that occurs when two incompatible images are presented to the two eyes. Even though the visual stimuli remain constant, visual perception alternates between the two monocular stimuli. Binocular rivalry is therefore extremely useful for understanding mechanisms underlying the selection of visual inputs for perception. Binocular rivalry projects in the lab include investigation of the effects of voluntary attention and pharmacological manipulations on perceptual alternations during binocular rivalry.

Silver MA, Stryker MP 1999. Synaptic density in geniculocortical afferents remains constant after monocular deprivation in the cat J Neurosci 19: 10829-10842.

Silver MA, Stryker MP 2000. Distributions of synaptic vesicle proteins and GAD65 in deprived and nondeprived ocular dominance columns in layer IV of kitten primary visual cortex are unaffected by monocular deprivation J Comp Neurol 422: 652-664.

Silver MA, Fagiolini M, Gillespie DC, Howe CL, Frank MG, Issa NP, Antonini A, Stryker MP 2001. nfusion of nerve growth factor (NGF) into kitten visual cortex increases immunoreactivity for NGF, NGF receptors, and choline acetyltransferase in basal forebrain without affecting ocular dominance plasticity or column development Neurosci 108: 569-585.

Silver MA, Logothetis NK 2004. Grouping and segmentation in binocular rivalry Vision Res 44: 1675-1692.

Silver MA, Ress D, Heeger DJ 2005. Topographic maps of visual spatial attention in human parietal cortex J Neurophysiol 94: 1358-1371.

Silver MA, Ress D, Heeger DJ 2007. Neural correlates of sustained spatial attention in human early visual cortex. J Neurophysiol 97:229-237.

Silver MA, Logothetis NK 2007. Temporal frequency and contrast tagging bias the type of competition in interocular switch rivalry. Vision Res 47:532-543.

More information

Silver Laboratory

Vision Science Web Page

Helen Wills Neuroscience Institute Page

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