Results obtained during the previous two grant periods have revealed new insights into the organization of primate visual cortex, most of which appear reasonable (in that they are consistent with previous observations), but few of which were known to be organized exactly as they have now been shown to be through optical imaging techniques. In addition to revealing the first actual maps of orientation selectivity, ocular dominance, and most recently position, results from this lab have additionally shown interactions among them that could facilitate perception. Funds are therefore requested to continue these efforts, using optical imaging to explore new functional architectures, or find them so they can be explored in greater detail in micro-electrodes and tracer injections at strategic locations. In one group of experiments, maps of retinotopic space will be obtained at different resolutions to find the minimum patterns where patterns can still be seen (Blasdel and Campbell, 1997), so that micro-electrodes can be used to explore the same areas to determine the extent to which this positional variance arises from cortical receptive field size or scatter, and whether the ration of contributions from these two varies at different locations (e.g., at the centers or edges of linear zones, singularities, blobs, etc.). Due to the recent publication of optical imaging studies based on shorter (600 nm) wavelength light, we also plan to continue comparing maps obtained at different (e.g., 610 and 720) wavelengths to determine the possible advantages of each as well as to explore possible benefits from obtaining images with both wavelengths - separately but simultaneously - used in combination. These experiments are designed to increase or understanding of visual information processing and associated structure-function relationships in the upper layers of primate visual cortex.
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