INVESTIGATING IMPAIRED SAFETY ENGAGEMENT IN PTSD PATIENTS: A BRAIN FUNCTIONAL CONNECTIVITY STUDY

Post-traumatic stress disorder (PTSD) is the main psychiatric sequela of exposure to potentially traumatic events. Previously, we reported the first fMRI evidence of impaired engagement in safety cues in patients with PTSD, a potential biomarker of this disorder. In that study, trauma-exposed controls and PTSD patients had been exposed to real photographs of intact (neutral) and mutilated bodies in two contexts: safe (described as makeup) and real (described as media coverage). In trauma-exposed controls, BOLD response in the supramarginal gyrus (SMG) to mutilated bodies was shown to be attenuated in the safe compared to the real context. PTSD patients showed similar BOLD responses across contexts, indicating impaired safety cue engagement. Here, we further analyzed this previously collected database to investigate the functional connectivity of brain networks involved in the impaired engagement of safety cues in patients with PTSD. A seed-to-voxel functional connectivity analysis with generalized psychophysiological interactions was conducted, with bilateral anterior and posterior subdivisions of the SMG as seeds. In controls, we observed increased connectivity of the left anterior SMG with the prefrontal cortex in the real context, and increased connectivity with the occipital cortex/left fusiform in the safe context. Patients showed increased connectivity of the right anterior SMG with the parietal cortex/postcentral gyrus in the real context, with no significant results in the safe context. Results revealed different patterns of functional connectivity in trauma-exposed controls and PTSD patients, further supporting the failure to engage in safety cues as a potential biomarker of PTSD.