Blue-Green Pathways in the Mammalian Retina

University Of Texas Hlth Sci Ctr Houston, Houston TX

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Abstract

DESCRIPTION (provided by applicant): This study will make a full description of the blue/green (S/M) color opponent ganglion cells in the rabbit retina. This description is intended to be full both in complete sampling of all such ganglion cells and also in depth of characterization of each type of S/M ganglion cell. Decades of early work in many species have led to description of usually only a single type, an S-ON and, much less often, an S-OFF type in addition or instead. Negative evidence coupled with recent discovery of an S-OFF ganglion cells produced by inversion of the S-ON bipolar cell signal has led to widespread rejection of the possibility of S-OFF pathways initiated by an S- OFF bipolar cell. Recent work has considerably advanced our understanding of the mechanisms of color opponency in the midget and small bistratified ganglion cells of primates. However, these 2 color opponent ganglion cells are often considered unique primate inventions, as they have no obvious parallels in other mammals. Further, the total number of chromatic ganglion cells and whether they suffice to produce cortical color mechanisms remains controversial. We will sample at least 3 S/M ganglion cell types that we have discovered in the rabbit retina, determine the nature of their inputs from other retinal neurons and how these interact to obtain very specific attributes of these color opponent cells, including their spatial and chromatic receptive field properties, the influence of surround stimuli and their anatomical underpinnings. These findings will be highly relevant to the understanding of color pathways as they underpin later central processing. S cone pathways in particular have been recently implicated in surprising areas not selective for color, including areas involved in form and motion vision, and which may be responsible for blindsight. S cone pathways are also important in research into migraine and glaucoma.