The primary goal of this research is to understand the neural pathways that form ganglion cell receptive fields in the mammalian and ultimately the human retina. Most of the techniques to be used in our investigations are anatomical but we continue an ongoing collaboration with Dr. Ralph Nelson (NINCDS) who uses physiological approaches to address the same questions. Major advances in our understanding of rod and cone pathways and ON and OFF center pathways in the mammalian retina have been gained by elucidating neural circuitry of physiologically identified, HRP-injected cells in cat retina, and we intend to continue with these same approaches. Electron microscopic studies of the synaptic input to X, Y and W type ganglion cells, of amacrine and bipolar cells is ongoing and will continue as more cells become available from the physiological experiments. To further our understanding of rod pathways in the mammalian retina we will continue a cross species analysis of Golgi impregnated neurons using opossum, ground squirre, rabbit, monkey and human retinas. Differences between mammalian retinas that have developed a visual streak rather than a fovea as a specialization will be investigated further by comparisons of Golgi impregnated rabbit and ground squirrel retinas to those of cat. Ganglion cells of these species will be marked with DAPI and Lucifer dye or HRP injection to show their morphology and orientation relative to the visual streak. Immunocytochemical studies on the cat retina, using antibodies to neurotransmitter candidates or their synthetic enzymes will be done in collaboration with Dr. Harvey Karten (Stony Brook). Thus cells that stain for TH, substance P, VIP, GAD and cholecystokinin will be stained in whole-mount, characterised at the light microscope level by comparison with Golgi impregnated counterparts and investigated by electron microscopy for synaptology. Human retina available from the Lions Eye Bank and from surgical procedures in the Ophthalmology Department will be studied by light (Golgi, fluorescence) and EM techniques (serial section analysis) to investigate the following a) morphology of the blue cones, b) distributions of rod amacrine cells and synaptology of the rod system and c) synaptology of the midget and parasol ganglion cells in comparison with cat beta ganglion cells.
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