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Neuroscience Graduate Program at UCSF
Structural Basis of Amblyopia and Strabismus
The visual system provides a supremely efficient means for the rapid assimilation of information from the environment to guide human behavior. Images are converted by the retina into action potentials, which are conduced along the optic pathway to the lateral geniculate body. Virtually the entire output of the lateral geniculate body is relayed to the primary visual cortex. Within the primary visual cortex, signals are processed by cells arranged within an elaborate system comprised of overlapping vertical columns and horizontal layers. Our first goal is to map the functional architecture of the primary visual cortex, to understand how groups of cells are organized in a modular fashion for information analysis. We are using autoradiography, axon tracing, cytochrome oxidase histochemistry, functional gene expression, and electrophysiology to accomplish this aim.
After initial processing the primary visual cortex, images are transferred to several dozen extrastriate visual areas, where perception takes place. Our second goal is to map the functional architecture, boundaries, layout, and topography of extrastriate visual cortex. At present, our attention is focused upon areas V2, V3, V4, and V5, which are located close to V1 in flat-mounted specimens of visual cortex.
Amblyopia is a disease of the cortex caused by visual deprivation. The most severe form occurs in a child who grows up with a dense unilateral cataract. Even after removal of the cataract, vision remains poor because connections serving the amblyopic eye are miswired within the brain. Our third goal is to delineate the critical periods for normal development and plasticity of the visual cortex, and to understand how projections within the cortex are disrupted by early visual deprivation and strabismus.
We use the macaque for most of our research, because it provides an excellent model for visual processing in the human brain. In addition, whenever possible, we conduct parallel anatomical studies in specimens of human visual cortex obtained post-mortem. This approach has allowed us to extend and confirm many of our findings, giving us confidence that our animal experiments are yielding valid insights into the function of the human visual cortex.We are pursuing two major projects in the laboratory. The first examines temporal coding of information in the anesthetized macaque monkey. We are comparing the information content in S-potentials (retinal ganglion cell afferents) and principal cells of the lateral geniculate nucleus. Our goal is to learn how information content changes across the geniculate synapse, and how it differs in geniculate cells driven by a normal eye versus an amblyopic eye. The second project addresses the mechanism of visual suppression in strabismus. We are seeking to learn, in awake monkeys raised with strabismus, how images from the deviated eye are suppressed perceptually. This may yield new insights into the mechanism underlying spontaneous development of strabismus in children and provide insight into how binocular rivalry is mediated in normal subjects.
Daniel L. Adams
Postdoctoral Fellow
Ph.D. University College, London
Functional Organization of the Monkey Visual Cortex for Stereoscopic Depth
John R. Economides
Postdoctoral Fellow
Ph.D. University of Texas
Smooth Eye Movements and Gaze Holding in Normal and Visually Deprived Monkeys
Lawrence C. Sincich
Postdoctoral Fellow
Ph.D. Harvard University
Local Circuits in Primary Visual Cortex
Cristina M. Jocson
Staff Research Associate I
Boston University
Bio-Engineering
Link to Publications via PubMed
Adams, DL, Sincich, LC, Horton, JC. "Complete Pattern of Ocular Dominance Columns in Human Primary Visual Cortex." J Neurosci 2007; 27: 10391–10403.
Sincich, LC, Adams, DL, Economides, JR, Horton, JC. "Transmission of Spike Trains at the Retinogeniculate Synapse." J Neurosci 2007; 27: 2683-2692.
Adams, DL, Horton, JC. "Monocular Cells Without Ocular Dominance Columns." J Neurophysiol 2006; 96: 1-12.
Sincich, LC, Horton, JC. "Input to V2 Thin Stripes Arises from V1 Cytochrome Oxidase Patches." J Neurosci 2005; 25(44):10087–93.
Sincich LC, Park KF, Wohlgemuth MJ, Horton JC. "Bypassing V1: a direct geniculate input to area MT" Nat Neuroscience, 2004; 7(10): 1123-35.
Adams DL, Horton JC. "A precise retinotopic map of primate striate cortex generated from the representation of angioscotomas." J Neurosci 2003; 23: 3771-89.
Adams DL, Horton JC. "The representation of retinal blood vessels in primate striate cortex." J Neurosci 2003; 23: 5984-97.
Sincich LC, Horton JC. "Independent projection streams from macaque striate cortex to the second visual area and middle temporal area." J Neurosci 2003; 23: 5684-92.
Adams DL, Horton JC. "Capricious expression of cortical columns in the primate brain." Nat Neurosci 2003; 6: 113-4.
Adams DL, Horton JC. "Shadows cast by retinal blood vessels mapped in primary visual cortex." Science 2002; 298: 572-6.
Sincich LC, Horton JC. "Divided by cytochrome oxidase: a map of the projections from V1 to V2 in macaques." Science 2002; 295: 1734-7.
Jonathan Horton, M.D./Ph.D.
Phone
415-476-8328
Physical Address
8 Koret Way
K-331
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UCSF
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Box 0730
San Francisco, CA 94143-0730
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