Primate visual cortex is subdivided into a number of visual areas that are hierarchically interconnected, and many of these areas are in turn subdivided into smaller, modular subregions. The long-term goal of this proposal is to contribute to our understanding of how visual information is processed by these subdivisions of visual cortex. The general strategy is to relate pathways interlinking specific sets of visual areas and subregions with functional streams specialized in the analysis of specific aspects of visual information. The project focuses on visual area V2, which contains a sequence of alternating stripe-like subregions revealed with cytochrome oxidase histochemistry (thick and thin stripes, and interstripes). A number of complementary anatomical and physiological experiments are proposed to address several issues bearing on the relationship of this modular organization with functional streams in visual cortex. The cortex will be physically unfolded and flattened to relate the anatomical and physiological data to the pattern of stripes over large regions of V2. One set of experiments will use electrophysiological and 2-deoxyglucose techniques to investigate the organization of the snipe pattern with respect to the visual field, paying especial attention to how dorso- ventral asymmetries in the stripe pattern are reflected in the topographic map. In addition, the possibility that each class of stripes has its own map of the visual field will be explored in detail. A second set of experiments will study specific cortical and subcortical connections of V2 in an effort to characterize further the degree of independence, or intermixing, of the processing pathways represented by the V2 stripe subregions. Results from this project will significantly extend our knowledge about functional visual pathways in normal individuals. They may also yield valuable clues for interpreting pathological conditions such as trauma and tumors involving cortical areas, and for designing treatment and artificial ways for aiding vision-impaired subjects.
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