Neural responses to emotional stimuli across the dissociative spectrum: common and specific mechanisms

Aim: Departing from existing neurobiological models of dissociation, the current study aims at conducting a quantitative meta-analytic review of neural responses to emotional stimuli among individuals ascribed to the dissociative spectrum (DS). Accordingly, the study explored common and specific brain mechanisms across borderline personality disorder, conversion/somatoform disorders, post-traumatic stress disorder [PTSD], PTSD related to repeated interpersonal traumatic experiences, dissociative disorders. Methods: The meta-analysis included studies that administered emotional stimuli during fMRI acquisition among individuals included in the DS. There were conducted 2 meta-analytic procedures: i) a Bayesian network meta-analysis for a region-of-interest (ROI)-based approach; ii) robust voxel-based approach. Results: Forty-four independent studies were included for a total of 1384 individuals (DS = 741 subjects). The network meta-analysis showed specific patterns of neural activity considering an extended brain network involved in emotion regulation for each condition ascribed to the DS. The voxel-based meta-analysis highlighted an increased activity of dorsal anterior cingulate cortex as a common neurological signature of the DS. Conclusion: The common neural feature of the DS captures an implicit appraisals of emotion-eliciting stimuli as threatening and/or noxious for mental and physical integrity of the individual together with painful subjective experiences associated to physiological emotional reactions. Specific brain responses across the DS suggested that the engagement in different mechanisms to address emotional stimuli - implicit avoidance reactions and attempts to over-control of affective states together with a disruption of integrative processes of emotional mind-body features.