Creation of direction selectivity in adult strobe-reared cats

Abstract

Animals raised in a stroboscopically illuminated environment have deficits in several visual functions, including visuo-motor integration¹, discrimination learning² and spatial contrast sensitivity³. Moreover, recordings from the visual pathways of strobe-reared animals show severe functional abnormalities, including greatly reduced selectivity for orientation and for directional motion in neurones of the visual cortex and superior colliculus^4–9. Subsequent normal visual experience improves cortical orientation selectivity, but does not alter the neural deficit in direction selectivity^6,7. As the motion-analysing capacities of strobe-reared animals have not been studied, we examined the ability of strobe-reared cats to discriminate stationary from moving patterns. We report here that the cats detected motion in the direction for which they had originally been trained much better than motion in other directions. In recordings from striate cortex in these animals, orientation and direction-selective neurones were encountered with a frequency much higher than that seen in strobe-reared cats not trained in motion discrimination, and comparable with that in normal cats. Moreover, the distribution of the preferred directions of these neurones was sharply biased towards the direction first seen hi training. We conclude that there exists an extended period of cortical plasticity in strobe-reared animals, which, in contrast to that previously reported⁶, includes plasticity of direction selectivity.