Date of Award

Fall 2011

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Clinical Psychology

First Advisor

Amy Van Hecke

Second Advisor

Matthew Sanders

Third Advisor

Paul Gasser, Nakia Gordon, Ed de St. Aubin

Abstract

Posttraumatic Stress Disorder (PTSD) is a response to trauma exposure that involves a number of symptoms that can be highly impairing to affected individuals. Only a subset of those exposed to traumatic events will develop the disorder, which is conceptualized as developing via conditional fear. Research into factors predisposing for PTSD is needed. Furthermore, little work has been done to investigate predisposing factors in children more specifically. This research tests the effects of stress exposure on subsequent fear learning, across developmental stages in mice, as a model for PTSD. Juvenile and adult male mice were exposed to chronic variable stress (CVS) for a period of 7d and their behavior was examined immediately thereafter. Both juvenile and adult mice exposed to CVS showed exaggerated anxiety behavior, as indicated by decreased exploratory behavior on the elevated plus-maze. While adult mice exposed to CVS displayed enhancements in long-term context fear learning, juvenile mice failed to display this pattern. Findings suggest differences in stress effects across developmental stages and provide further evidence supporting dissociation of the anxiety and fear pathways in the rodent brain. While PTSD does occur in childhood, onset is more common in adulthood, which may be reflective of differential developmental schedules in the fear and anxiety pathways.