Default mode network mechanisms of repeated transcranial magnetic stimulation in heroin addiction

Abstract Repetitive transcranial magnetic stimulation (rTMS) over the left dorsolateral prefrontal cortex (DLPFC) has been found could reduce the craving of heroin dependent (HD) individuals, but the underlying mechanisms of the anti-craving effect of rTMS is unknown. It has been shown that abnormalities in the default mode network (DMN) are consistent findings in HD individuals, in which the craving was involved. We assessed the effect of rTMS on the activity of the DMN and the relation to treatment response. Thirty HD individuals were included in this self-controlled study. All HD participants received a 7-times 10Hz rTMS during a week. The craving, withdrawal symptom and resting-state functional magnetic resonance imaging data were collected before and after the rTMS treatment. Thirty demographically matched healthy subjects who did not receive rTMS were included as controls. We focused on the change of coupling seeded from the medial prefrontal cortex (MPFC), posterior cingulate cortex (PCC) and bilateral inferior parietal lobe (IPL) which are core regions of the DMN. The craving and withdrawal symptom score of the HD individuals significantly decreased after rTMS treatment. The left IPL-left middle frontal gyrus coupling and the left IPL-right inferior occipital gyrus coupling significantly decreased, and the change of the left IPL-left middle frontal gyrus coupling positively correlated with the change of the drug-cue induced craving. The rTMS could modulate the coupling between the DMN and ECN. The alteration of the left IPL-left middle frontal gyrus coupling may play an important mechanistic role in reducing the drug-cue induced craving.