INTRODUCTION

It has been proposed that social conflict, particularly when it results in social defeat or subordination, is a major stressor in humans and that this type of stress contributes to numerous diseases and psychopathologies including a variety of mood and anxiety disorders (Agid, Kohn, & Lerer, 2000; Bjorkqvist, 2001; Gardner, 2001; Nemeroff, 1998). Understanding the dramatic impact that stressful experiences have on social behavior is necessary if we are to develop better ways of treating individuals who develop maladaptive responses to these events. Use of animal models of stress-induced behavioral plasticity are necessary for the exploration of the neural mechanisms and circuitry underlying these changes. This chapter reviews some recent data from experiments aimed at understanding the neural basis of a long lasting, stress-induced change in behavior, “conditioned defeat,” which is observed in Syrian hamsters, as well as other species, following exposure to social stress (i.e., social defeat). The purpose of such experiments is to increase our understanding of the basic neural mechanisms that mediate experience-induced changes in social behavior, particularly in response to aversive experience.

An organism's ability to learn about its environment and to alter its behavior in response to external stimuli is critical for survival and reproductive success. In particular, it is vital that organisms have the ability to respond appropriately to, and to remember long-term, potentially threatening events (see Wiedenmayer, this volume).