Abstract / Summary
Abstract Traumatic experiences can lead to profound disruptions in identity and sensory perception, often manifesting as a sense of estrangement from one’s own body. These dissociative symptoms are now alarmingly observed in over half of individuals with post-traumatic stress disorder (PTSD), defining a dissociative subtype (PTSD+DS). While neurophysiological changes across numerous hierarchical brain levels have been identified, the precise mechanisms driving this fractured experience of reality remain unclear. In particular, the role of the thalamus, a central hub for brain-body integration, is thought to be critical but has not been fully characterized in this context. Using the largest connectivity analysis including PTSD+DS, we show that dissociation is defined by a unique shift towards inefficient communication with insufficient thalamo-cortical connectivity. This is revealed through two nearly disjointed but hyperconnected network of brain regions – one exclusively containing higher-level cortical regions with diminished thalamic integration, alongside another with enhanced thalamic-brainstem/cerebellar coupling. Finally, novel analyses localized dissociation-specific shifts in cortico-thalamic synchrony to visual and sensorimotor regions, potentially explaining poor integration of perceptual and bodily information in PTSD+DS. With the ever-increasing prevalence of PTSD+DS, especially in a world with increasing wars, these findings suggest supplementing front-line psychotherapies with adjunctive interventions promoting better bottom-up sensorimotor processing.