Behavioral correlates of learned aggression in male mice

Abstract

The aims of this paper are to study the aggressive behavior in male mice with consecutive experience of victories in 2, 10, and 20 days (T2, T10, and T20 winners) of daily agonistic confrontations under the sensory contact model and to determine the most probable behavioral domains that should be used as animal models for learned aggression in humans. It has been shown that the structure of winners' behavior changes from test to test: the attacking behavior prevailed (81% of the total time) in the behavior of T2 winners. Attacks and diggings (herein: digging up and scattering the litter on the partner' territory) prevailed in the behavior of T10 winners (each approximately 40%). T20 winners demonstrated aggressive grooming half of the testing time and digging behavior 25% of the time. Correlational analysis revealed that the number of significant correlations between the behavioral domains (attacking, digging, aggressive grooming, self-grooming, threats, rotations) and between different behavioral parameters (latency, number, total and average time) of one behavioral domain are growing from the second test to twentieth test, and the relationships between the behavioral domains change qualitatively. The following may be regarded as elements of learned aggression in male mice: (1) appearance of aggressive grooming instead of the intensive attacking behavior and (2) involvement of the digging behavior in the hostile behavior together with the threats and attacking behavior. Negative correlations between parameters of the behavioral domains may testify to the replacement of one behavioral pattern by another and reflect learned behavior. Positive correlations between certain behavioral domains may reflect the formation of a common motivational background for the winners' behavior. Aggr. Behav. 26:386–400, 2000. © 2000 Wiley-Liss, Inc.