The video imaging technique we developed 11 years ago (Blasdel and Salama, 1986) has provided numerous insights into the functional organization of primate visual cortex. Not only has it provided the first (and still the only) maps of orientation preference in visual areas 1 and 2, it has also provided the only maps of different response patterns (e.g., orientation, ocular dominance, retinopy) from the same cortical location: maps on the basis of which previously unknown local interactions were inferred (Blasdel, 1992; Obermayer and Blasdel, 1993). Funds are therefore requested to continue these efforts in three groups of experiments that should expand our understanding further. In one group of experiments we plan to compare differential images, obtained simultaneously and without dye from the same cortical regions, with two or more different wavelengths of light. Of particular interest will be the relative independence of changes monitored at different wavelengths, and ways in which these changes in reflectance might be combined to infer additional information (e.g., about depth), or to achieve superior signal to noise ratios. In another set of experiments, we plan to continue our analysis of ways in which optically imaged patterns reflect the receptive field properties of upper layer neurons. In a final group of experiments, we plan to compare differential images of ocular dominance, position, and orientation so that new information about local interactions (e.g., between ocular dominance and position, or between position and orientation, etc.) can be inferred. Collectively, these experiments are designed to increase our understanding of visual information processing in the visual cortex of primates.