Modulation effects of repetitive transcranial magnetic stimulation on target and indirect target nodes in patients with major depressive disorder

Clinical studies intensively highlight two critical brain regions, i,e, dorsal lateral prefrontal cortex (DLPFC) (target node) and subgenual anterior cingulate cortex (sgACC) (indirect target node) for the treatment of neuroimaging-guided repetitive transcranial magnetic stimulation (rTMS) in major depressive disorder (MDD). However, it remains unclear whether the clinical rTMS treatment could modulate the activity of the target and indirect target nodes in MDD patients. We aim to identify the rTMS-induced alteration of brain local and functional connectivity (FC) activities in the target and indirect target nodes. 38 patients with MDD were recruited for taking part in the 2-week rTMS treatment. We identified left DLPFC and right sgACC as the target and indirect target nodes for each participant, using the neuroimaging guided method, and further explored the rTMS-induced modulation on the brain functional activity of the two nodes. Ultimately, 28 patients were included in the analysis. We found that subjects had significant improvement in depressive symptoms, and their brain functional activities were reorganized. rTMS reduced the FC activity between the target and indirect target nodes, while the brain local activity in these nodes did not show rTMS-induced changes. The FC reduction was not associated with improvement in depressive symptoms. These results confirmed the clinical significance of the target node (DLPFC) and indirect target node (sgACC) in the rTMS treatment of MDD, and further shed light on the brain functional reorganization underpinning clinical practice of rTMS.