Problems in the study of rodent aggression

Laboratory research has produced detailed descriptions of aggression and defense patterns in the rat, mouse, and hamster, showing strong similarities, but also some differences, across these species. Research on target sites for attack, in conjunction with analyses of the situational antecedents of attack behaviors and of responsivity of these to conditions that elicit fear, has also provided a strong basis for analysis of offensive and defensive aggression strategies and for identification of combinations of these modalities such as may occur in maternal aggression. These patterns have been empirically differentiated from phenomena such as play fighting or predation and compared for laboratory rodents and their wild ancestors. An array of tasks, suitable for use with pharmacological and experimental manipulations, is available for analysis of both aggression and defense. These developments should produce a firm basis for research using animal models to analyze a broad array of aggression-related phenomena, including systematic approaches to understanding the normal antecedents and consequences of each of several differentiable types of aggressive behavior. Despite this strong empirical and analytic background, laboratory animal aggression research has been in a period of decline, spanning several decades, relative to comparable research focusing on areas such as sexual behavior or stress. Problems that may have contributed to the relative neglect of aggression research include confusion about the interpretation of different tasks for eliciting aggression; difficulties and labor intensiveness of observational measures needed for an adequate differentiation of offensive and defensive behaviors; analytic difficulties stemming from the sensitivity of offensive aggression to the inhibitory effects of fear or defensiveness; lack of a clear relationship between categories of aggressive behavior as defined in animal studies and those used in human aggression research; and the social and political difficulties undermining support for research on a topic that, when applied to humans, provides a stigmatizing label. While all of these provide some rationale for eschewing aggression research, aggression remains a serious social, economic, health, and political problem. The neglect of research in this area contributes to an ongoing failure to understand the degree of similarity across mammalian species in the antecedents, neural systems, behavioral expression, and outcomes of aggression. This failure, in turn, hinders analyses of normal and abnormal forms of aggression and of the appropriate roles of the former in society, reducing the possibility of sensitive and effective approaches to control inappropriate human aggressive behaviors. (C) 2003 Elsevier Inc. All rights reserved.