Kaczkurkin, Antonia2014-10-242014-10-242014-08https://hdl.handle.net/11299/167172University of Minnesota Ph.D. dissertation. August 2014. Major: Psychology. Advisor: Shmuel Lissek, Ph.D. 1 computer file (PDF); viii, 123 pages.A review of the literature demonstrates a lack of research on fear-generalization processes in many anxiety disorders including obsessive-compulsive disorder (OCD) and posttraumatic stress disorder (PTSD). Chapter 2 represents the first study that attempted to investigate the generalization of conditioned fear in individuals with obsessive-compulsive traits using startle EMG and behavioral measures. The results of this study demonstrated that individuals with high levels of Threat Estimation as measured by the Obsessive Beliefs Questionnaire (OBQ-44) displayed overgeneralization of fear responses to a greater range of stimuli resembling the danger cue than those with low levels of Threat Estimation. In addition, despite etiological theories proposing that fear conditioning and overgeneralization of fear play prominent roles in the development and maintenance of PTSD, little research had been done on the neurobiological mechanisms that contribute to fear conditioning processes in PTSD patients and none have been specifically conducted on generalization. Chapter 3 investigated the neurobiological substrates associated with the overgeneralization of conditioned fear in PTSD patients using behavioral, skin conductance, and functional magnetic resonance imaging (fMRI) measures. This study provides evidence that PTSD patients demonstrate overgeneralization of conditioned fear in the dorsal medial prefrontal cortex, bilateral insula, left and right caudate, left inferior parietal lobule, and right superior frontal gyrus. This body of work provides novel evidence regarding the generalization of conditioned fear in OCD and PTSD.enFear conditioningfMRIGeneralizationObsessive compulsive disorderPosttraumatic stress disorderStartle EMGPsychologyThesis or Dissertation