Effects of temporal neocortical ablation on visual discrimination learning sets in monkeys.

Abstract

The nature of the visual deficits in monkeys following temporal lobe lesions was studied. The hypothesis that the visual disturbances after such a lesion were secondary to the loss of general working attitude in the formal training situation was tested. Three immature monkeys (Macaca mulatta) were trained preoperatively to form learning sets for visual object discriminations and for pattern discriminations. They were also given a nonspatial delayed response problem. After bilateral temporal neocortical ablations, all animals lost the learning set for pattern discriminations, and were not able to regain it even after prolonged retraining. Two monkeys also lost the learning set for object problems, but reacquired this with a large amt. of saving. The third animal did not lose the learning set for object discriminations after the operation. Postoperatively, one monkey lost the ability to perform the nonspatial delayed response, whereas the other two showed good retention on this problem. The differential results obtained for two kinds of learning sets were interpreted as not supporting the hypothesis proposed. They rather pointed to the possibility that the temporal lobe removals may disturb the monkey''s visual attention.