Emotional and Cognitive Influences on Visual Search
The question of how one's emotional state affects one's ability to perform cognitive tasks has long captivated scientists. In the work described in this thesis, a visual search task was employed as a proxy for cognition while images of emotional facial expression served to influence emotional experience. Previous models of the interaction between emotion, cognition, and visual perception have focused on the negative impact of emotion on cognition and behavioral performance. The goal of the experiment described in this thesis was to investigate whether exposure to an emotional stimulus can have positive or negative effects on a subsequent visual search task. Specifically, the study was aimed at exploring the neural correlates of behavioral effects, BOLD effects, and functional connectivity between the seed regions amygdala, V1, and V2 with networks in the brain corresponding to cognition, particularly visual attention. Nineteen subjects performed the search task during fMRI, while their eye movements, pupillometric data and manual responses were measured. Furthermore, the subjects completed several emotional rating scales to assess their individual levels of anxiety and hedonic capacity. Subjects performed more accurately on the visual search task in trials preceded by fearful or happy face stimuli as compared with a neutral one. Functional connectivity measures based on psychophysiological interaction and the contrast of the fearful and neutral conditions revealed a widespread pattern of enhanced functional connections between the amygdala seed and areas located in early and higher order extrastriate cortex including inferotemporal gyrus and fusiform gyrus. In addition, higher connectivity with the medial dorsal nucleus of the thalamus was observed. Also for the Fearful → Neutral contrast, V1 had higher functional connectivity with medial prefrontal cortex, superior frontal gyrus, posterior cingulate, and the pulvinar. Furthermore, the exposure to a happy stimulus relative to a neutral one resulted in increased connectivity to the inferior parietal lobule and precuneus, both of which are involved in the frontoparietal network. Comparison of fearful and happy functional connectivity patterns revealed higher V1 and V2 connectivity with medial frontal gyrus and anterior cingulate during the fearful condition, a difference which was also correlated with subject trait anxiety. Taken together, the results indicate that exposure to emotional stimuli can have enhancing effects on visual search performance which are related to changes in the functional relationships between brain regions including the amygdala (emotion processing), inferior parietal lobule and precuneus (cognition), and striate/extrastriate cortex (visual).
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