The aftermath of trauma on resting state source-level MEG microstate dynamics

Background: Traumatic events can disrupt psychological functioning, leading to conditions such as post-traumatic stress disorder (PTSD). However, not all trauma-exposed individuals develop PTSD. While neurobiological alterations in PTSD are well-documented, the impact of trauma exposure on resting-state (RS) brain activity, particularly dynamics of brain states (microstates, MS), remains unclear.Aim: To address this gap, this study investigates RS brain activity of trauma-exposed non-PTSD (TENP) individuals compared to PTSD patients, exploiting magnetoencephalography (MEG) and source-level MS analysis.Methods: RS-MEG recordings were obtained from 33 traumatized people (16 PTSD, 17 TENP). Source localization was performed using eLORETA on individual cortical space and parcellated based on the Human Connectome Project atlas. MS analysis at parcel-level provided four MS topographies and related metrics.Results: MS analysis at parcel-level provided four topographies revealing distinct trauma-related modulations in RS dynamics. PTSD patients showed dominance in a bilateral MS overlapping the fronto-parietal network - linked to stress regulation and self-referential processing - positively correlated with symptom severity. Conversely, TENP individuals exhibited dominance in two MSs negatively correlated with symptoms: a right-lateralized cingulo-opercular network supporting salience processing and a left-lateralized sensorimotor network.Conclusions: These findings suggest that trauma exposure differently affects spatio-temporal dynamics of MEG oscillations. Resilience may arise from successful integration of cognitive and sensorimotor processes, detectable as distinct patterns of brain dynamics during rest.