Frontolimbic lesions and social behavior in the rat

Abstract

The social behavior of rats with chronic lesions to the medial frontal cortex, orbital frontal cortex, hippocampus, septum or amygdala was studied in four different situations: large open field, small open field, shock induced aggression and muricide. All lesions altered social behavior but the effects of the different lesions could be dissociated from one another. Lesions to the hippocampus dramatically reduced contact in open field tests and almost totally eliminated shock induced aggression. Lesions to the amygdala and septum also reduced the level of shock induced aggression but whereas amygdala lesions significantly decreased contact, septal lesions did not. Rats with lesions to the medial or orbital aspects of the prefrontal cortex differed from one another as the rats with orbital lesions exhibited consistently low contact scores and the rats with medial lesions did not, while both groups showed increased levels of shock induced aggression. None of the lesions significantly altered muricide.