Amacrine Cell Circuitry Mediating Visual Function

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DESCRIPTION (provided by applicant): Our deepest understanding of retinal activity has been derived from studies that show how identified amacrine cell types mediate specific visual functions. Saccadic suppression and figure-ground separation by the polyaxonal amacrine cells, directional selective movement detection by the starburst amacrine cells, and the processing of rod vision by the All amacrine cells are examples of sophisticated function mediated by well-defined retinal circuitry involving specific amacrine cell types. The strategy in those studies was to determine how excitatory and inhibitory signals generated by amacrine cells are integrated to form meaningful retinal activity. There exist an additional two dozen amacrine cells in the retina whose morphology and stratification has been well defined, but whose visual functional roles still remain obscure. It is the goal of this proposal to investigate the visual functional role of many of these less defined amacrine cells. Our strategy is to utilize our recent studies of ganglion cell function that have defined a dozen different "feature detectors" formed by the neatly stratified dendrites of a dozen different ganglion cell types distributed throughout the depth of the inner plexiform layer. These studies define the space, time, stratification and phase properties of excitation and inhibition arriving at the dendrites of each ganglion cell type. The inhibitory components of these responses reflect the space, time, stratification and phase properties of different amacrine cell types whose processes costratify with the dendrites of each ganglion cell type. We will record from specific amacrine cell types in retinal slices and correlate their space time phase and stratification properties with the inhibitory properties of the ganglion cells with which they costratify. Through this correlation process we hope to be able to describe the role of specific amacrine cells in generating different components of visual function.