DEFENSIVE BEHAVIORS IN RATS FOLLOWING SEPTAL AND SEPTAL-AMYGDALA LESIONS

Rats with anterior septal lesions showed a pattern of consistent enhancement of defensive behaviors normally elicited by threatening conspecifics, with no enhancement of attack or general reactivity. Further division of this group indicated that damage to sites anterior and ventral to the septal area, sites previously implicated in the septal syndrome, produces maximal effect on these behaviors. When amygdala lesions are combined with septal damage this enhanced defensive responding is almost completely eliminated. The septal syndrome probably represents hyperdefensiveness to conspecific threat stimuli rather than aggression or increased general reactivity. Amygdaloid mechanisms may also be involved in the regulation of conspecific defensive behaviors.