Aggressive behavior in the rat: Effects of isolation, and olfactory bulb lesions

Abstract

Forty-nine male hooded rats 84 or 94 days of age were used as subjects. Ss were housed individually or in groups for 1 month and were then subjected to an olfactory bulbectomy or a sham operation. They were again housed either individually or in a group cage for 1 month. Ss were then tested for mouse killing, frog killing, reactions to a gloved hand including squealing, escape, and biting, intermale aggression and shock-induced aggression. Results indicate that biting the glove was the only type of aggressive behavior significantly affected by olfactory bulb lesions. Postoperative isolation increased mouse killing, and escape from the gloved hand and the number of bites on the hand. There was also a significant operation by postoperation isolation interaction for number of bites on the glove. Mouse killing and frog killing were significantly correlated as were escape and squealing; escape and bites; and bites and mouse killing. Intermale aggressive behavior was notably absent and was unaffected by any condition. It was concluded that this study adds further evidence that aggression is not a unitary phenomenon and that different manipulations differentially affect different kinds of aggression.