Recent brain imaging studies implicate dysfunction of limbic and paralimbic circuitry, including the amygdala and medial prefrontal cortex (MPFC), in the pathogenesis of posttraumatic stress disorder (PTSD) during traumatic recollection and imagery. However, the relationship between activity in these regions and general emotional processing unrelated to traumatic experience has not been fully examined.
To investigate activity in the limbic and paralimbic brain regions in PTSD in response to a challenge with emotionally salient generic visual images.
Cross-sectional, case-control study.
Academic medical center.
Sixteen Vietnam veterans with combat-related PTSD (PTSD group), 15 combat-exposed Vietnam veterans without PTSD (combat control group), and 15 age- and sex-matched healthy controls (normal control group).
Main Outcome Measures
We used positron emission tomography to study regional cerebral blood flow while participants viewed complex visual pictures with negatively valenced/aversive, nonaversive (“neutral”), and blank pictures. Psychophysiologic and emotional self-report data were also recorded.
All 3 groups activated the dorsal MPFC to general salient content. Controls without PTSD activated the left amygdala in response to aversive stimuli. Normal controls activated the ventral MPFC and combat-exposed non-PTSD and PTSD participants exhibited either no response or deactivation in these regions, respectively, during negative emotional experience.
Consistent with current functional neuroanatomic models, patients with PTSD exhibited altered neural responses in the amygdala and ventral MPFC during the processing of emotionally salient but trauma-unrelated stimuli, potentially reflecting disorder-specific changes. Activation of the amygdala and lack of ventral MPFC deactivation to negatively valenced images in combat controls may reflect compensatory changes after trauma exposure that are not associated with PTSD.