EFFECTS OF EARLY EXPOSURE TO INTERMALE AGGRESSION ON THE AGGRESSIVENESS OF ADULT MALE-MICE VARYING IN THEIR GENETIC DISPOSITION FOR AGGRESSIVE-BEHAVIOR

This study examined whether adult male aggression is influenced by eit her visual or olfactory exposure in early postnatal life to brief epis odes of aggression. Another focus of interest was the interplay betwee n a genetic disposition for aggressive behavior and early exposure exp eriences. The subjects used in the study were male mice of the 49th ge neration of selection for high (Turku Aggressive, TA) and low (Turku N on-Aggressive, TNA) levels of aggressiveness. Moderately aggressive ma les of the parental strain (Normal, N) were also used. Subjects of eac h strain were exposed from 21 to 32 days of age to fighting males eith er behind a wire mesh or glass screen. Control subjects were isolated during the entire experimental period. At 90-100 days of age, each sub ject was tested three times for its aggressiveness. Exposure to fighti ng males behind a wire mesh screen enhanced later aggressiveness of ju venile male mice. Juveniles exposed solely to visual cues were compara ble to isolates, both groups showing less adult aggression. Early expe rience and the genetic disposition for aggression were correlated; TA males showing the greatest increase in aggressive behavior. The role o f early olfactory learning is discussed. (C) 1993 Wiley-Liss, Inc.