Neural Profiles of Fear and Guilt: An Investigation Using Functional Magnetic Resonance Imaging and Spectroscopy
Type of DegreePhD Dissertation
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Fear and guilt are emotional processes that are implicated in the development and maintenance of psychiatric disorders. While research on fear has established a consistent neural network, a corresponding ‘guilt’ network remains elusive. Few research studies have directly compared these two affective states within a single paradigm. Here, functional magnetic resonance spectroscopy (fMRS) and functional magnetic resonance imaging (fMRI) were used to elucidate neurophysiological changes in response to script-driven imagery tailored to participant’s fear- and guilt-evoking experiences. We hypothesized that fear would have greater neural activation in limbic structures and guilt, given its nature as a secondary emotion, would activate structures involved in cognitive processing. Furthermore, we anticipated differences in gamma-aminobutyric acid (GABA), glutamate, and glutamine between conditions. When comparing fear to neutral conditions, we corroborate previous evidence demonstrating increases throughout the limbic system using fMRI. A statistically significant network for guilt was not found, when compared to the neutral condition. FMRS analyses, focused in the anterior cingulate cortex, did not reveal any differences between the fear and guilt conditions. Comparing fear and guilt directly, exploratory post hoc functional connectivity analyses provided evidence for increased connectivity between limbic structures and regions associated with visualization (i.e., occipital cortex) during fear, and greater connectivity with structures involved in personal moral judgment (i.e., inferior frontal gyrus) and memory (i.e., hippocampus) during guilt. Data from this project provides evidence for differential neural networks for fear and guilt, supporting efforts to reconsider models of psychiatric disorders in which these two emotions are prevalent.