PHOTOPIGMENTS AND COLOR-VISION IN THE NOCTURNAL MONKEY, AOTUS

The owl monkey (Aotus trivirgatus) is the only nocturnal monkey. The p hotopigments of Aotus and the relationship between these photopigments and visual discrimination were examined through (1) an analysis of th e flicker photometric electroretinogram (ERG), (2) psychophysical test s of visual sensitivity and color vision, and (3) a search for the pre sence of the photopigment gene necessary for the production of a short -wavelength sensitive (SWS) photopigment. Both electrophysiological an d behavioral measurements indicate that in addition to a rod photopigm ent the retina of this primate contains only one other photopigment ty pe-a cone pigment having a spectral peak ca 543 nm. Earlier results th at suggested these monkeys can make crude color discriminations are in terpreted as probably resulting from the joint exploitation of signals from rods and cones. Although Aotus has no functional SWS photopigmen t, hybridization analysis shows that Aotus has a pigment gene that is highly homologous to the human SWS photopigment gene.