THE CONTRIBUTIONS OF ON-PATHWAYS AND OFF-PATHWAYS TO CONTRAST SENSITIVITY AND SPATIAL-RESOLUTION IN GOLDFISH

DL-2-amino-4-phosphonobutyric acid (APB) reduces the sensitivity of ON - and OFF-responses in goldfish retina, although the ON-responses are reduced significantly more than the OFF-responses. This paper describe s the effects of APB on behavioral sensitivity of goldfish to spatial sinusoidal gratings. Fish were classically conditioned to suppress res piration upon presentation of gratings drifting at 1 Hz; contrast thre sholds were measured by an observer-based two-alternative forced-choic e procedure. Thresholds were repeated following intraocular injections of APB or physiological saline. Saline had no effect, but APB dramati cally reduced contrast sensitivity and shifted contrast sensitivity fu nctions to lower spatial frequencies. The results suggest that both ON - and OFF-pathways are necessary for normal spatial vision and that th e effects of APB are consistent with the disruption of both ON- and OF F-pathways.