Striate cortex ablation and spatial vision.

Abstract

Normal and visually decorticate rats were trained to orient to a luminous target. All subjects reached the same criterion of orientation accuracy, but operated subjects required more training and exhibited greater response latency throughout testing. To determine if visually decorticate subjects located the target according to the retinal position of its image, or only by sampling luminous flux density at different points in space, field-displacing wedge prisms were placed before the subjects' eyes to laterally displace the retinal locus of the target image without affecting luminous flux information. Prism imposition shifted orientation toward the virtual target position for all subjects. In a second study, translucent plastic was place over the subjects' eyes to disrupt the retinal topography and location of the target image while again leaving luminoux flux unaffected as a potential cue. All animals showed a dramatic and complete disruption of target localization once the diffusing material was applied. The data were considered as support for the hypothesis that 'spatial' vision survives visual decortication.