Neural Mechanisms Involved in Emotion /Attention Interactions

157 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007.Although it is well-established that emotional context modulates attention and that this modulation varies across different types of clinical groups, the exact mechanisms involved remain unclear. Dorsolateral prefrontal cortex (DLPFC), amygdala, dorsal (dACC), and rostral (rACC) anterior cingulate cortex (ACC) have been shown to play a critical role in the interaction of emotion and attention processes. The present project proposes a model of brain connectivity that involves these brain regions and functional connections between them as well as how these connections vary in non-clinical control, depression and anxiety groups. Two critical aspects of this model of brain connectivity were examined. Firstly, although functional differentiation of dACC and rACC for aspects of cognitive and emotional function has received considerable indirect support, no direct statistical test of this specialization has been published. Using fMRI, parallel tasks, and within-subject analysis, the present study directly tested the proposed specialization of ACC subdivisions. A Task x Region interaction confirmed more dACC activation during color-word distractors and more rACC activation during emotion-word distractors. Activity in ACC subdivisions differentially predicted behavioral performance. Connectivity with prefrontal and limbic regions also supported distinct dACC and rACC roles. Findings provide direct evidence for differential engagement of ACC subdivisions in cognitive and emotional processing and for differential functional connectivity in the implementation of cognitive control and emotion regulation. Secondly, context-dependent interactions between DLPFC, amygdala, dACC, and rACC were explored in clinical and non-clinical groups performing the emotional Stroop task. Compared to depression and control groups, anxiety groups showed greater interference from negative stimuli. Control and depression participants showed a stronger positive dACC-DLPFC relationship for negative versus neutral words, indicating greater dACC-DLPFC implemented control in the presence of negative distractors. In contrast, individuals with anxiety showed a less positive dACC-DLPFC relationship for negative versus neutral words, indicating a weakening of this relationship in the presence of emotionally aversive stimuli, thereby resulting in poorer behavioral performance. The rACC-amygdala relationship showed a similar pattern of relationships. Findings provide important insight into mechanisms involved in disruption of cognitive function in the presence of affective stimuli as well as how this relationship manifests in clinical conditions.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD