Functional connectivity of dissociative responses in posttraumatic stress disorder: A functional magnetic resonance imaging investigation

Background: The purpose of this study was to assess interregional brain activity covariations during traumatic script-driven imagery in subjects with posttraumatic stress disorder (PTSD). Methods: Functional magnetic resonance imaging and functional connectivity analyses were used to assess interregional brain activity covariations during script-driven imagery in PTSD subjects with a dissociative response, PTSD subjects with a flashback response, and healthy control subjects. Results. Significant between-group differences in functional connectivity were found. Comparing dissociated PTSD patients and control subjects' connectivity maps in the left ventrolateral thalamus (VD) [-14, -16, 4] revealed that control subjects had higher covariations between activations in VLT and in the left superior frontal gyrus (Brodmann's area [BA] 10), right parabippocampal gyrus (BA 30), and tight superior occipital gyrus (BA 19, 39), whereas greater covariation with VLT in dissociated PTSD subjects occurred in the fight insula (BA 13, 34), left parietal lobe (BA 7), right middle frontal gyrus (BA 8), superior temporal gyrus (BA 38, 34), and fight cuneus (BA 19). Comparing dissociated PTSD and flash back PTSD connectivity maps in the fight cingulate gyrus [3, 16, 30] revealed that dissociated PTSD subjects bad higher covariations between activations in this region and the left infetior frontal gyrus (BA 47). Conclusions: Greater activation of neural networks involved in representing bodily states was seen in dissociated PTSD subjects than in non-PTSD control subjects. These findings might illuminate the mechanisms underlying distorted body perceptions often observed clinically during dissociative episodes.