Lessons From Neuroimaging Symptom Provocation Studies

Rapidly evolving brain neuroimaging techniques such as magnetic resonance imaging (MRI) and positron emission tomography (PET) have proven useful instruments to explore the pathogenesis and pathophysiology of PTSD. Structural abnormalities in PTSD found with MRI include nonspecific white matter lesions and decreased hip-pocampal volume. These abnormalities may reflect pretrauma vulnerability to develop PTSD or they may be a consequence of traumatic exposure, PTSD, and/or PTSD sequelae. Rauch, van der Kolk, and colleagues conducted the first PET scan study of patients with PTSD (Rauch et al., 1996). When PTSD subjects were exposed to vivid, detailed narratives of their own traumatic experiences, they demonstrated increased metabolic activity only in the right hemisphere, specifically, in the areas that are most associated with emotional appraisal: the amygdala, insula, and the medial temporal lobe. During exposure to their traumatic scripts, there was a significant decrease in activation of the left inferior frontal area—Broca's area, which is responsible for motor speech. Most neuroimaging studies have found activation of the cingulate cortex (which possibly plays an inhibitory role) in response to trauma-related stimuli in individuals with PTSD, but others have found decreases, even while using similar activation paradigms.

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