Undergraduate Honors Theses

Thesis Defended

Fall 2019

Document Type

Thesis

Type of Thesis

Departmental Honors

Department

Psychology & Neuroscience

First Advisor

Dr. Steven Maier

Second Advisor

Dr. Heidi Day

Third Advisor

Dr. Ricardo Stephen

Fourth Advisor

Dr. Jose Amat

Abstract

Prefrontal cortex dysfunction is implicated in a range of stress related neuropsychiatric disorders, with cognitive flexibility deficits being a major symptom. Clinically, females are much more likely to develop a neuropsychiatric disorder following a traumatic life event. The ability to exert control over stressors has been shown to mitigate the effects of stress in male rats but not in female rats in some behavioral tests. Catecholamines are known to have elevated release within the prefrontal cortex following acute stress and to contribute to prefrontal cortex dysfunction. In this study, male and female rats were subjected to inescapable stress and escapable stress as an animal model of stress coping. One set of groups received attentional set shift testing to evaluate cognitive flexibility following stress. In vivo microdialysis during stress was conducted for the second set of groups. Overall, the data showed that escapable stress in male rats blunted both catecholamine release within the ventromedial prefrontal cortex and cognitive flexibility deficits following stress. By contrast, in females, the data showed that escapable stress failed to mitigate both the increase in catecholamine release within the ventromedial prefrontal cortex and cognitive flexibility deficits following stress. Interestingly, the data demonstrated significantly that inescapable stress blunted dopamine release in the ventromedial prefrontal cortex in female rats. Future research needs to be performed with a larger number of subjects due to the lack of statistical significance for portions of this data attributable to a low number of subjects. These experiments provide possible evidence for why female rats lack the protective effects of behavioral control over a stressor. In addition, this research contributes to the growing body of literature on stress controllability consequences, which could be applicable to human neuropsychiatric disorders.

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