FUNCTIONAL ANALYSIS OF RETINAL GANGLION CELLS

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The long-term objective of this proposal is to understand the principles of organization of the mammalian retina and the importance of such organization for the overall functioning of the visual system. Retinal ganglion cells are known to be organized into distinct, functional classes. Each class is responsible for presenting a particular view of the visual world to specific, highly specialized nuclei of the brain. In this context, the immediate goals of this project are threefold. First, to elucidate the role played by the different classes of ganglion cells by characterizing and comparing the visual properties of individual cells in an animal preparation. Second, to relate these properties to relate these properties to a newly described component of the electroretinogram that is used clinically for diagnosis of such human diseases as multiple sclerosis, optic atrophy and glaucoma. Third, to isolate the optical and retinal factors which limit peripheral vision in man. Representative cells of the different classes of ganglion cells will be isolated for study in cat by introducing a microelectrode into the eye of an anesthetized animal. Contrast sensitivity will be determined for sinusoidal grating stimuli over the full spectrum of spatial frequencies and orientations. Comparisons will be drawn between the performance of different types of cells at fixed retinal locations and also between cells of the same type but at different retinal locations. Simultaneously with the recording of responses from individuals cells, the electroretinogram will be recorded by a second electrode. Comparisons will be drawn between the two sets of responses to determine which classes of retinal ganglion cell, if any, are correlated with this pattern- evoked electroretinogram. Peripheral vision in human subjects will be evaluated with a newly-discovered class of patterned stimuli which are visible but which cannot be resolved properly. This mode of vision, called aliasing, ususally occurs only in the peripheral field and may hold the keys to understanding the quality of normal peripheral vision as well as the cause of visual dysfunction in the residual sight of persons deprived of foveal vision because of age related, hereditary, or acquired macular degeneration.