Hagit Cohen

Posttraumatic stress disorder (PTSD) affects about 20-30% of exposed individuals. Clinical studies of PTSD generally employ stringent criteria for inclusion in study populations, and yet in animal studies the data collection and analysis are generally expressed as a function of xposed versus nonexposed populations, regardless of individual variation in response. There is a need for a better parallel between the approach to understanding animal behavioral models and the contemporary understanding of the clinical conditions. We conceived an approach to understanding the consequences of stress exposure in a manner that would enable us to segregate the study animals into groups according to the degree of their response to a Stressor, i.e., the degree to which their behavior is altered or disrupted. The idea was to set apart the most clearly affected, i.e., extreme behavioral response group from the minimal behavioral response at the extremes, and to establish a middle group of partial responders, groups that better reflect behavioral criteria akin to clinical symptoms already defined. This chapter presents an overview of a series of studies, examining the contribution, validity, and practicality of this animal model.