All ETDs from UAB

Advisory Committee Chair

David C Knight

Advisory Committee Members

Edwin W Cook

Rajesh K Kana

Jerzy P Szaflarski

Kristina M Visscher

Document Type

Dissertation

Date of Award

2016

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

The biobehavioral response to acute stress is an allostatic process. Dysregulation of the stress response has been implicated in allostatic load and the pathophysiology of a wide range of physical and psychological disorders. There have been considerable advances within the last two decades in the field’s understanding of allostatic load and a consistent finding across studies has been that individual differences are the norm rather than the exception. That is, exposure to stress seems to have minimal negative consequences for some, but substantial negative consequences for others. Determining the neural processes associated with individual differences in stress reactivity may advance our understanding of stress susceptibility and resilience. This project employed magnetic resonance imaging to assess the relationship be-tween neural connectivity and acute stress. Specifically, this project assessed neural con-nectivity during predictable and unpredictable stress, connectivity during psychosocial stress, and structural connectivity associated with individual variability in stress reactivi-ty. We also investigated the psychophysiological and endocrine correlates of the stress response via skin conductance response (SCR), heart rate (HR), and salivary cortisol ex-cretion. Participants provided a continuous self-report measure of expectation of predict-able and unpredictable stressors to assess stress expectancy. Participants also provided self-reported stress levels to assess the subjective stress of the psychosocial stress task. Finally, we also examined whether individual differences in anxiety level varied with stress reactivity and neural connectivity to stress. We observed differences in effective brain connectivity to predictable and unpre-dictable stressors. Specifically, dorsolateral PFC (dlPFC) connectivity was greater during predictable than unpredictable stressors. In contrast, the dorsomedial PFC (dmPFC) demonstrated greater connectivity when the stressor was unpredictable compared to pre-dictable. We also observed individual variability in white matter structural connectivity within the cingulum associated with greater stress reactivity to a psychosocial stressor. Further, we also observed decreased network efficiency and network resilience during psychosocial stress. Finally, this project demonstrated individual variability in negative affectivity associated with dlPFC effective connectivity to the amygdala and with white matter tractography connecting the amygdala to the hypothalamus. This research suggests that stress is regulated by connectivity of a network that includes the dlPFC, dmPFC, vmPFC, amygdala, and hypothalamus. Further, this project demonstrated that stress dis-rupts the efficiency and structural connectivity of this network.

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