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The general goal of our research is to assess the function of
brain structures such as the amygdala, medial prefrontal cortex, and
hippocampus in PTSD. Our research suggests that the amygdala and
dorsal anterior cingulate cortex are hyper-responsive while the
ventral medial prefrontal cortex is hypo-responsive in individuals
with this disorder.
Current Research Questions:What is the Origin of Functional Brain Abnormalities in PTSD?
PTSD is a relatively recent addition to the psychiatric diagnostic system used in the United States, and researchers have only just begun to investigate the biological bases of this disorder. In order to determine whether the functional brain abnormalities in PTSD are acquired characteristics of the disorder or familial vulnerability factors for its development, we are conducting fMRI studies of amygdala, medial prefrontal cortex, and hippocampal function in identical twin pairs. Within each pair, one individual served in Vietnam and the other twin did not. In half of the pairs, the combat-exposed twin has PTSD; in the other half, the combat-exposed twin does not have PTSD (see figure below).
Within the twin design, we are also studying brain structure, white matter tracts, and the relative concentrations of metabolites in the brain, such as N-acetyl aspartate. Additionally, we are examining glucocorticoid stress hormone receptors within blood cells in order to determine why individuals with PTSD may be more sensitive to the effects of the stress hormone cortisol.
In the future, we hope to expand this line of research to include twin veterans of more recent military conflicts, such as Operation Enduring Freedom and Operation Iraqi Freedom.Can Neuroimaging Measures Predict Treatment Response?
This line of research seeks to determine whether pre-treatment neuroimaging measures of amygdala and medial prefrontal cortex function can predict response to treatment with behavioral therapy in PTSD. Preliminary findings show that higher pre-treatment activation of the ventral medial prefrontal cortex and lower pre-treatment activation of the amygdala in response to predictors of potential threat (i.e., fearful facial expressions) are associated with greater symptomatic improvement following behavior therapy.
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