Development of tactile discrimination capacity in Macaca mulatta. II. Effects of partial removal of primary somatic sensory cortex (SmI) in infants and juveniles.
Four infant macaques between the ages of 2.7 and 6.7 weeks and 5 juvenile macaques between the ages of 78.6 and 108.3 weeks received partial, unilateral lesions of the hand projection in primary somatic sensory cortex (SmI) (either Brodmann's area 3 or areas 1 and 2 combined). Following these partial SmI lesions, both infants and juveniles showed some initial impairment on acquisition and slightly inferior performance on the size-ALL task. Both infants and juveniles were able to discriminate smaller size differences with the contralateral hand than partial SmI-lesioned adult macaques with similar SmI lesions in previous studies. After partial SmI lesions, infants and juveniles were markedly retarded in the acquisition of texture discriminations indicating that, as in adult macaques, these separate SmI areas contribute jointly to texture discrimination capacity. However, in contrast to adult animals, all infants and most juveniles were able to master all levels of texture tasks after 2-4 months of training. On the texture-ALL task, the performance of partial SmI-lesioned infants was slightly inferior to that of normal infants with the contralateral hand but significantly better than normal infants on the ipsilateral hand. Lesioned juveniles showed impairment on both contralateral and ipsilateral hands. Recovery of near-normal tactile function in both partial SmI-lesioned infants and juveniles is seen although mature levels of function are typical of normal infants over this same age range.
D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology*; D003213:Conditioning, Psychological; D004193:Discrimination Learning; D007839:Functional Laterality; D008251:Macaca / Q000502:physiology*; D008253:Macaca mulatta / Q000502:physiology*; D014110:Touch