Effects of somatosensory thalamic and cortical lesions on roughness discrimination in the albino rat☆

Abstract

Abstract Rats were tested in a T-maze for acquisition of a tactile discrimination between the rough and smooth surfaces of a moderately fine grade of sandpaper. Animals with electrolytic lesions centered in the lemniscal projection to the ventral nuclear complex of the thalamus and animals with aspirative ablations centered in the forepaw somatosensory 1 area of the cortex exhibited poorer group mean performance than did control animals, but the experimental groups did not differ from each other. A second, more difficult discrimination task between two fine grades of sandpaper yielded the same result. Experimental animals were, on the average, deficient on all but one of a battery of neurological tests. Thalamic lesioned animals exhibited a more severe deficient on some tests than did cortical lesioned animals. Neither lesion size nor lesion locus could account for the substantial variation between the performance of individual animals within each experimental group.