Brain functional network after intervention with rTMS in OCD individuals is pushed to a more unstable state to decrease obsessive behaviors

Repetitive Transcranial Magnetic Stimulation (rTMS) is an FDA-approved treatment for Obsessive-Compulsive Disorder (OCD). Nevertheless, understanding a global mechanism of the changes in the brain functional network could lead us to optimize the effectiveness of this method. Therefore, reorganization of the brain functional network after intervention with rTMS was investigated in this study based on the structural balance theory. We hypothesized that functional plasticity after the intervention is imposed on the brain functional network by changes in the topology of triadic associations in the network and leading the network to a higher balance energy level (less stable). Consequently, brain functional networks of OCDs were calculated based on the phase lag indexes of their resting state EEGs before and after intervention in a frequency specific manner. Subsequently, global network parameters including number of positive and negative links, types of triadic interactions (balanced or unbalanced triads), tendency of negative/positive links to make hub, and balance energy level were compared between pre and post-intervention. Our findings revealed a significant decrease in weak-balanced and an increase in strong-unbalanced triads, particularly in the Beta І frequency band. In addition, significant decrease was observed in tendency of negative links to make hubs across certain frequency bands. These changes after intervention increase the network balanced energy level toward a less stable state. We hope these findings pave the way for refining the strategy of rTMS interventions by reorganizing the brain functional network.