Date on Master's Thesis/Doctoral Dissertation

12-2025

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Psychological and Brain Sciences

Degree Program

Experimental Psychology, PhD

Committee Chair

Depue, Brendan

Committee Member

DeMarco, Paul

Committee Member

Lynn, Andrew

Committee Member

Wouwe, Nelleke van

Author's Keywords

human neuroimaging; amygdala; conditioning; extinction

Abstract

Fear plays a crucial role in survival but can lead to psychological disorders when dysregulated. Fears can be innate due to evolutionary relevance or learned through associative processes, where predictive accuracy of threat is pivotal. Disruptions in fear neurocircuitry contribute to anxiety disorders, characterized by heightened activation and impaired learning. Fear conditioning and extinction paradigms based on classical Pavlovian conditioning have been used to study mechanisms underlying fear learning. Using this experimental model, fear networks in rodents have been described in detail with clear distinction between conditioning and extinction neural functioning. Yet, there is no consensus on the neurobiological processes in humans during fear conditioning and extinction. Neuroimaging research has been able to generally accept a canonical ‘fear network’, however, one of the main regions agreed upon as being central to fear processing, the amygdala, shows the least consistent findings. The present study utilized high resolution imaging to assess detailed amygdala function during fear learning and extinction. 30 participants underwent 1.5 mm3 fMRI scanning while performing a fear acquisition and extinction task. Behavioral and task results were able to validate the efficacy of the task design through increased responses to fear stimuli and extinguished responses to neutral stimuli. Neuroimaging results were able to delineate subregions of the amygdala with significant differences in activation profiles. Neurobehavioral results highlighted the relationship between anxiety and dysregulated fear processing. These results provide further insight into the human fear network and the role the amygdala plays in fear learning.

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