Early versus late visual cortex lesions: Effects on receptive fields in cat superior colliculus

Abstract

Cats that sustain lesions of the visual cortex early in life appear to perform certain visual discrimination tasks better than those operated as adults. This study sought to determine whether this recovery of visual capacities was accompanied by reorganization of single cell responses at the level of the superior colliculus. Areas 17 and 18 were ablated in adult cats and in kittens at various times during the neonatal period. Responses of units in superior colliculus ipsilateral to the lesion were recorded following a prolonged recovery period. Following cortical lesions, collicular units rarely exhibited direction selectivity, binocularity was reduced in the majority of animals, and the ocular dominance distribution was biased toward the contralateral eye. The reduction of direction selectivity and binocularity were unrelated to the animal's age at operation.