Effects of lesions to the dorsal and ventral hippocampus on defensive behaviors in rats

Abstract

This study investigated the role of the dorsal and ventral hippocampus in both unconditioned and conditioned defensive behaviors by examining the effects of pretraining ibotenic acid lesions to the dorsal or ventral hippocampus in Long Evans hooded male rats exposed to three types of threat stimuli, cat odor, a live cat and footshock. Conditioned defensive behaviors were assessed in the same context 24 hours after the threat exposure. During unconditioned test trials, DR lesions did not significantly alter behaviors during exposure to cat odor, a live cat, or footshock. Additionally, DR lesions failed to modify conditioned behaviors during all three tests of defense. In contrast, VR lesions significantly reduced both unconditioned and conditioned defensive behaviors during cat odor and footshock, while only reducing defensive behaviors during the unconditioned cat exposure trail. These results suggest a role for the VR in modulating anxiety-like behaviors in certain animal models of defense.