PROJECT SUMMARY/ABSTRACT The visual system has emerged as a premier model for understanding information processing by neurons. Within vision, the submodality of color provides a particularly attractive experimental platform: we know a tremendous amount about the phenomenology of color perception and can explain some aspects of color perception, quantitatively and with high precision, by well understood physiological processes. As a result of this knowledge, we can quickly and accurately diagnose many distinct forms of color blindness and can build devices that render colors accurately. On the other hand, surprising holes in our knowledge remain. The proposed research will fill these holes in our knowledge by revealing the specializations of three types of neurons in area V1 for color vision. Three specific aims are planned: 1) Electrophysiological characterization of parvalbumin-expressing inhibitory neurons. 2) Testing the hypothesis that color-sensitive complex cells enhance edges between materials of different reflectance. 3) Testing the hypothesis that double-opponent cells are the physiological basis for color induction by simultaneous color contrast. The proposed experiments will extend our knowledge toward an understanding of the principles that give rise to perception and its disorders. Such an understanding promises to provide the means to promote recovery of visual function following trauma or neurological disease.