Corticolimbic blood flow in posttraumatic stress disorder during script-driven imagery

Background: Functional neuroimaging experiments targeting personal recall of emotional events may help elucidate neural substrates underlying posttraumatic stress disorder (PTSD). Studies suggest that limbic and paralimbic function might be altered in PTSD, as compared with trauma-exposed control subjects; however, little is known about functional changes resulting from traumatic experience itself. The present study examined both PTSD-specific and trauma-specific regional cerebral blood flow (rCBF) patterns during script-driven imagery. Methods: Sixteen combat veterans with PTSD (PP); 15 combat veterans without PTSD (CC); and 14 healthy, aged-matched noncombat control subjects (NC) underwent [¹⁵O] H₂0 positron emission tomography (PET) scanning during script-driven imagery of emotionally evocative and neutral autobiographic events. Results: Differential patterns of activation were detected in amygdala and medial frontal cortex. Past trauma experience was associated with decreased amygdala activity (i.e., less activity than healthy control subjects); however, combat control subjects deactivated this region (i.e., greater activity to neutral scripts). All subjects deactivated medial frontal cortex; PTSD patients had greater rostral anterior cingulate (rACC) deactivation compared with control groups, who deactivated ventromedial prefrontal cortex (vmPFC). Conclusions: Trauma-specific patterns may represent potential compensatory changes to traumatic reminders, while patterns observed only in the PTSD group may reflect neural substrates specific to PTSD pathophysiology.