Microsynt: exploring the syntax of EEG microstates
AUTHORS: Artoni F, Maillard J, Britz J, Brunet D, Lysakowski C , Tramèr MR, Michel CM
NeuroImage, : 120196, June 2023
Collective research has identified a key electroencephalogram (EEG) signature in patients with posttraumatic stress disorder (PTSD), consisting of abnormally reduced alpha (8-12 Hz) rhythms. We conducted a 20-session, double-blind, randomized controlled trial of alpha-desynchronizing neurofeedback in patients with PTSD over 20-weeks. Our objective was to provide mechanistic evidence underlying potential clinical improvements by examining changes in aberrant PTSD brain rhythms (namely, alpha oscillations) as a function of neurofeedback treatment.
We randomly assigned participants with a primary diagnosis of PTSD (n = 38) to either an experimental group (n = 20) or sham-control group (n = 18). A multi-channel EEG cap was used to record whole-scalp resting-state activity pre- and post-neurofeedback treatment, for both the experimental and sham-control PTSD groups.
We firstly observed significantly reduced relative alpha source power at baseline in patients with PTSD as compared to an age/sex-matched group of neurotypical healthy controls (n = 32), primarily within regions of the anterior default mode network. Post-treatment, we found that only PTSD patients in the experimental NFB group demonstrated significant alpha resynchronization within areas that displayed abnormally low alpha power at baseline. In parallel, we observed significantly decreased PTSD severity scores in the experimental neurofeedback group only, when comparing baseline to post-treatment (Cohen’s d = 0.77) and 3-month follow-up scores (Cohen’s d = 0.75), with a remission rate of 60.0% at the 3-month follow-up.
Overall, our results indicate that neurofeedback training has the capacity to rescue pathologically reduced alpha rhythmicity, a functional biomarker that has repeatedly been linked to symptoms of hyperarousal and cortical disinhibition in PTSD. This randomized-controlled trial provides long-term evidence suggesting that the “alpha rebound effect” (i.e., homeostatic alpha resynchronization) occurs within key regions of the default mode network previously implicated in PTSD.