Effects of serial lesions of somatosensory cortex and further neodecortication on tactile retention in rats.

Four groups of rats with bilateral lesions of somatosensory cortex and one of animals sustaining only sham operations were tested for retention of a difficult tactile discrimination. Two of the lesion groups had serial ablations, in one case with interoperative testing, and two had one-stage lesions. Bilateral ablations of somatosensory cortex severely retarded retention in all lesion groups relative to the control group and serial and one-stage groups did not differ from each other. The sham operated rats then experienced lesions of cortex anterior and posterior to the somatosensory areas. These lesions only marginally affected retention. Somatosensory cortex then was ablated and severe performance decrements were seen. Removal of additional neocortex in animals that previously had relearned the discrimination after somatosensory cortex lesions also resulted in very poor retention. These data demonstrate the importance of the somatosensory cortex in mediating tactile discriminations and suggest that non-somatosensory cortex may play a role in recovery after somatosensory cortical lesions.