Subcortical mechanisms in emotional behavior: the duration of affective changes following septal and habenular lesions in the albino rat.

Abstract

Experiments investigate further the duration and specific character of behavioral changes in albino rats following lesions in the septal forebrain region and habenular complex of the thalamus. Both pre- and post-operatively, data were collected with respect to (a) the acquisition, retention, and extinction of a conditioned emotional reponse (CER) of the "fear" or "anxiety" type, (b) the magnitude of the startle response, and (c) general emotional reactivity as reflected in a seven-item rating scale. The results confirmed the previously reported post-operative increase in magnitude of both emotional reactivity and startle response for the septal animals, but not the habenula animals. All animals returned to normal within 60 days after operation. Six of the twelve septal animals showed a temporary reduction in the strength of the CER post-operatively, apparently related to the extent of involvement of the fornix system and anterior thalamic nuclei. Habenular lesions produced no effect upon the acquisition or retention of the CER, but extinction of the emotional response was significantly more rapid in the habenula animals. This effect seemed to be related to the extent of the damage to the habenular complex.