Rewarding Network Mechanism of Left Orbito-frontal Cortex Transcranial Magnetic Stimulation in Depression

Objective The difficulties in the clinical antidepressant treatment lead to the pursuing of more effective methods such as transcranial magnetic stimulation (TMS). Mixed findings from DLPFC targeted TMS result in the exploration of optimal stimulation location. Disturbed function of obitofrontal cortex (OFC) has been indicated in depression, which is involving in the remission of depression. However, whether it could be a more specific treating target is not tested. Simultaneously, disturbed reward network (RN) has been confirmed in depression, however, whether this could be improved by TMS treatment remains unclear. Methods Fourteen patients with major depressive disorder (MDD) were allocated in a four-week course of OFC targeted TMS. Motivated by the literature, before and after the treatment, the function connectivity of RN with the seed of ventral striatum was conducted. The results were also compared with the data from 33 healthy controls. Results The OFC targeted TMS improved the clinical depression significantly and enhanced the function connectivity within the RN effectively. Specifically, lower baseline dorsolateral striatum connectivity predicted strong therapeutic effect of TMS on depression, while lower baseline insula connectivity predicted weak therapeutic effect on depression. Conclusions The findings offer the first experimental evidence of the therapeutic effect of OFC targeted TMS on clinical depression, enhanced function connectivity within RN might be the potential neural mechanism (Fig. 1). Lower dorsolateral striatum connection might be a reliable neural biomarker of strong responding for TMS treatment, which helps to identify the patients who will be cured by TMS most effectively.