Advisory Committee Chair
David C Knight
Advisory Committee Members
Rajesh K Kana
Adrienne C Lahti
Edwin W Cook Iii
Amy J Knight
Document Type
Dissertation
Date of Award
2018
Degree Name by School
Doctor of Philosophy (PhD) College of Arts and Sciences
Abstract
Approximately 25 million United States (U.S.) citizens experience a potentially traumatic event each year, and almost 90% of the U.S. population will experience at least one traumatic event in their lifetime. Trauma exposure is the primary antecedent to the development of Post-Traumatic Stress Disorder (PTSD), a highly debilitating mental health disorder characterized by chronic cognitive-affective dysfunction. However, there is considerable variability in susceptibility to PTSD. Specifically, trauma exposure may result in PTSD for one person, but not another. Therefore, a better understanding of the acute processes that affect brain function, structure, and biochemistry following trauma exposure is critical for the development of early interventions and treatment techniques to mitigate the social, emotional, and financial burden of PTSD. The present dissertation project utilized neuroimaging to investigate the acute impact of post-traumatic stress on the human brain. Multiple magnetic resonance imaging (MRI) modalities were used to assess brain function, structure, and biochemistry. Recently trauma-exposed (TE) participants were recruited within thirty days of a traumatic event and completed a differential Pavlovian fear conditioned procedure during functional MRI (fMRI), diffusion weighted imaging (DWI), and proton magnetic resonance spectroscopy (1H-MRS). During the initial visit (i.e., < 1 month assessment), we collected the MRI data in addition to a psychological measure of post-traumatic stress severity (Posttraumatic Diagnostic Scale). Post-traumatic stress severity was assessed again three months post-trauma. We identified acute effects of post-traumatic stress on brain function during the Pavlovian fear conditioning procedure. Specifically, TE participants showed heightened neural activity within prefrontal regions such as the dorsal anterior cingulate cortex (ACC). Further, heightened neural activity within the prefrontal cortex (PFC) and inferior parietal lobule (IPL) acutely following trauma was associated with reduced post-traumatic stress severity three months post-trauma. Post-traumatic stress severity also varied with the white matter microstructure of the cingulum bundle, uncinate fasciculus, and fornix/stria terminalis. Finally, we observed a positive relationship between glutamate/glutamine concentrations within the dorsal ACC and post-traumatic stress severity. Together, the current dissertation demonstrates post-traumatic stress impacts the neural network that mediates cognitive-affective function. Further, individual variability in the neurobiology of the network appears to mediate future post-traumatic stress symptom expression.
Recommended Citation
Harnett, Nathaniel Gene, "Human Neurobiology Following Trauma: Assessing Brain Function, Structure, And Biochemistry" (2018). All ETDs from UAB. 1874.
https://digitalcommons.library.uab.edu/etd-collection/1874