Potential Neurophysiological Mechanisms of 1Hz-TMS to the Right Prefrontal Cortex for Depression: An Exploratory TMS-EEG Study in Healthy Participants

Background: The present study aimed to examine the acute neurophysiological effects of 1Hz transcranial magnetic stimulation (TMS) administered to the right dorsolateral prefrontal cortex (DLPFC) in healthy participants. Methods: TMS combined with simultaneous electroencephalography (EEG) recording was conducted for 21 healthy participants. For the right DLPFC, 1Hz-TMS (100 pulses/block x 17 sessions) was applied in the resting-state, while for the left DLPFC, 1Hz-TMS (100 pulses/block x 2 sessions) was administered during the verbal fluency tasks (VFTs). For TMS-EEG data, independent component analysis (ICA) was applied to extract TMS-evoked EEG potentials to calculate TMS-related power as well as TMS-related coherence from the F4 and F3 electrode sites during the resting-state and VFTs. Results: TMS-related power was significantly increased in alpha, beta, and gamma bands by 1Hz-TMS at the stimulation site during the restingstate, while TMS-related power was significantly increased in alpha and beta bands but not in the gamma band during the VFTs. On the other hand, TMS-related coherence in alpha and beta bands significantly increased but not in gamma band by 1Hz-TMS that was administered to the right DLPFC in resting-state, whereas there were no significant changes in coherence for all frequency bands by 1Hz-TMS that applied to the left DLPFC during the VFTs. Conclusions: Collectively, 1Hz-repetitive TMS (rTMS) to the right DLPFC may rapidly neuromodulate EEG activity, which might be associated with a therapeutic mechanism for depression.

Automated summary

The study aimed to investigate the acute neurophysiological effects of 1Hz transcranial magnetic stimulation (TMS) on the right dorsolateral prefrontal cortex (DLPFC) in healthy participants. The results showed that 1Hz-TMS significantly increased TMS-related power in alpha, beta, and gamma bands at the stimulation site during the resting state, while only alpha and beta bands were affected during verbal fluency tasks (VFTs). In addition, 1Hz-TMS to the right DLPFC increased TMS-related coherence in alpha and beta bands during the resting-state, but no significant changes were observed during the VFTs with left DLPFC stimulation.