Recovery of tactile function after damage to primary or secondary somatic sensory cortex in infant Macaca mulatta.

These studies were designed to determine the basis for recovery of tactile function after the removal of primary (SI) or secondary (SII) cortex in infant Macaca mulatta. From previous studies we know that although removal of SI or SII in the adult macaque produces severe and irreversible impairment on a variety of tactile tasks, normal function can be obtained after partial or total SI lesions in the infant. From the present studies we have found that, as with SI, neither unilateral nor bilateral removals of SII in infants significantly affected the acquisition of or the performance on size tasks, but did cause a temporary delay in acquisition of texture tasks. Performance on texture threshold tasks was normal. The removal of the remaining SI in a juvenile animal that had received a unilateral SI lesion in infancy did not disrupt the recovered function, indicating that recovery is not mediated by the intact SI. However, when SI and SII were removed together from the same hemisphere in an infant, either sequentially or simultaneously, major impairment in the acquisition of texture tasks followed. These results suggest that although SI and SII are necessary for normal tactile function in the adult macaque, they show an equipotentiality for mediating normal tactile function after damage to either area in infants.