New Animal Model

Pam Litvak (Biology)

Using a New Animal Model of Psychological Stress to Test the Effects of Control vs. Predictability on Brain Structure and Function

Humans can experience feelings of stress even in the absence of real danger, by anticipating what will happen in the future. This type of psychological stress can either lead to anxiety or depression, or it can boost “psychological immunity” by helping us learn coping behaviors that we can then apply in other stressful situations. The latter outcome is termed stress resistance. Environmental factors, such as a stressor’s controllability and predictability, likely influence the direction of outcome. Here I propose to use a recently developed animal model of psychological stress to explore the interaction of control and predictability in shaping coping behaviors and the development of stress resistance. Preliminary data validate this model as inducing psychological stress in rats. Stressed animals showed no signs of anxiety or depression, and also developed active coping behaviors that were applied in novel, stressful situations. However, this increase in stress resistance came at a cost to working memory, a cognitive function that is dependent on the prefrontal cortex (PFC) and the hippocampus. We believe that this cognitive impairment indicates a neural shift in the stressed animals from the executive control of the PFC to rapid, reflexive actions associated with the amygdala and related brain areas. The 2 experiments described in this proposal will further investigate this neural shift. Experiment #1 tests the effects on spatial working memory in the Barnes maze. Experiment #2 assesses possible deficits in behavioral flexibility (a sign of PFC impairment) using a ruleshifting task.

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