The lasting effects of 1Hz repetitive transcranial magnetic stimulation on resting state EEG in healthy subjects

Abstract

Repetitive Transcranial magnetic stimulation (rTMS) is a noninvasive brain stimulation technique that able to influence cortical excitability. Low-frequency rTMS (stimulation frequency ≤1Hz) induces long-lasting inhibitory effects on cortical excitability. In order to study the effects of 1Hz rTMS of the motor cortex on neuronal activity, 20 healthy subjects were recruited to receive rTMS, and electroencephalography (EEG) in resting condition with eye open were recorded before rTMS, at 0min, 20min, 40min, 60min after rTMS. In multiple frequency bands, power values on each channel were calculated, and functional connectivity between two channels was assessed using phase synchronization. We found an increase in power of theta-band oscillations in the frontal and the central brain areas immediately after rTMS. And alpha resting power in the central-parietal brain area did not change immediately after rTMS, but increased at 20min after rTMS. Moreover, there is a widespread increase in functional connectivity after rTMS in the theta band, whereas widespread decreases in the functional connectivity were found in the alpha band after rTMS. At the same time, there was no significant recovery on power and functional connectivity at 60min after rTMS. These results provide an evidence for a transient reorganization of neuronal activity after 1Hz rTMS over the motor cortex. In addition, low-frequency rTMS produces widespread long-lasting alterations in cortical functional connectivity.