fMRIfunctional connectivity of the periaqueductal gray inPTSDand its dissociative subtype
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AbstractBackgroundPosttraumatic stress disorder (PTSD) is associated with hyperarousal and active fight or flight defensive responses. By contrast, the dissociative subtype ofPTSD, characterized by depersonalization and derealization symptoms, is frequently accompanied by additional passive or submissive defensive responses associated with autonomic blunting. Here, the periaqueductal gray (PAG) plays a central role in defensive responses, where the dorsolateral (DL‐PAG) and ventrolateralPAG(VL‐PAG) are thought to mediate active and passive defensive responses, respectively.MethodsWe examinedPAGsubregion (dorsolateral and ventrolateral) resting‐state functional connectivity in three groups:PTSDpatients without the dissociative subtype (n = 60);PTSDpatients with the dissociative subtype (n = 37); and healthy controls (n = 40) using a seed‐based approach via PickAtlas andSPM12.ResultsAllPTSDpatients showed extensiveDL‐ andVL‐PAGfunctional connectivity at rest with areas associated with emotional reactivity and defensive action as compared to controls (n = 40). Although allPTSDpatients demonstratedDL‐PAGfunctional connectivity with areas associated with initiation of active coping strategies and hyperarousal (e.g., dorsal anterior cingulate; anterior insula), only dissociativePTSDpatients exhibited greaterVL‐PAGfunctional connectivity with brain regions linked to passive coping strategies and increased levels of depersonalization (e.g., temporoparietal junction; rolandic operculum).ConclusionsThese findings suggest greater defensive posturing inPTSDpatients even at rest and demonstrate that those with the dissociative subtype show unique patterns ofPAGfunctional connectivity when compared to those without the subtype. Taken together, these findings represent an important first step toward identifying neural and behavioral targets for therapeutic interventions that address defensive strategies in trauma‐related disorders.
