LACK OF BEHAVIORAL EFFECTS FOLLOWING DESTRUCTION OF SOME THALAMIC ASSOCIATION NUCLEI IN MONKEY

Abstract

NEUROPSYCHOLOGICAL studies on the monkey's association cortex have demonstrated that various behavioral effects may be produced by ablating different cortical regions. These behavioral changes are not strictly localized in discrete areas; instead, certain behavioral disturbances tend to follow the damage of one particular region more consistently than damage to other regions. Thus, visual discrimination learning is disturbed by temporal neocortical ablation, although occasionally also by prefrontal lesions. The efficiency of performing somesthetic discriminations and the conditional reaction problem is impaired by lesions in either the parietotemporal or the prefrontal area. The ability to do the delayed reaction problem is almost completely lost after prefrontal removal but is only infrequently and slightly retarded after preoccipital and temporal extirpations (for references to the literature on this subject, see the review by Chow and Hutt¹). Furthermore, these behavioral changes seem to result from the cortical damage alone; they are not correlated with