Date of Award

Spring 1-1-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology & Neuroscience

First Advisor

Marie T. Banich

Second Advisor

Sona Dimidjian

Third Advisor

Joanna Arch

Fourth Advisor

Wendy Heller

Fifth Advisor

Christopher Lowry

Abstract

Previous research has indicated that people with depression exhibit altered cognitive control functioning when confronted by negative information or stress. However, identifying the factors that drive such altered functioning, or how to protect the ability to implement cognitive control, remain topics of debate. The current thesis explores these themes: what is it about the content of salient, distracting stimuli that predicts altered cognitive control in depression, how is such interference manifested on the level of brain activation, and what protects cognitive control functioning in the face of such stimuli. Study 1 investigated the relationship between depression and brain activation in response to ignoring negatively valenced words in a subclinical population. We found that higher depression predicted increased activity in brain regions implicated in self-referential thought and emotion processing, and increased recruitment of areas involved in the top-down control of attention. These patterns were specific to negative distractors, suggesting that altered brain response at higher levels of depression is in response to negative emotional information. Study 2 investigated whether having behavioral control over stressors would buffer women with clinical or subclinical depression from the negative effects of stress exposure on cognitive control. We found that people exposed to controllable stress performed better on a test of general executive functioning than those exposed to uncontrollable stress, but that more severe depressive symptoms predicted poorer performance within the controllable stress group. Notably, this increase in impairment at higher levels of depression was partially mediated by more extreme responses to stress. These results suggest that if individual differences in stress sensitivity are taken into account, people with depression may also benefit from having behavioral control over stressors. The present studies support the theory that depression is related to changes in behavioral and neural functioning when exerting cognitive control over negative information or after stress exposure, but that behavioral strategies may help protect the ability to implement cognitive control.

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