Change of EEG activity by repetitive Transcranial Magnetic Stimulation

The aim of this study is to investigate the effects of repetitive Transcranial Magnetic Stimulation (rTMS) to the electroencephalogram (EEG). rTMS of 100 pulses were applied over the primary motor area in the left hemisphere. The EEG was recorded during and after rTMS of 100 pulses applied. rTMS of 100 pulses consists of rTMS of 1 Hz 5 pulses repeated 20 times at ten seconds intervals. Also, the effects of the pulses number were investigated. Power spectrums of EEG amplitude were calculated. After the 100 pulses of rTMS applied, it was found that the power spectrum of EEG amplitude is significantly increased at the opposite electrode to the stimulus point in the right hemisphere. There was no significantly change in the amplitude of power in gamma-band by sham stimulation. Current distribution which induced by TMS was calculated. It was found that the effects appeared in the contralateral hemisphere at 27.5 ms after TMS applied. Also, the electrical activity which induced by TMS were appeared stronger in last 5 pulses of rTMS than first 5 pulses of rTMS.