ABSTRACT
Repetitive transcranial magnetic stimulation (rTMS) has been applied in a variety of diseases due to the clinical effects through the plasticity of the brain. The effects of TMS appear differently depending on the methods of stimulation. Single pulse TMS depolarizes and discharges nerves temporally under the cortex areas stimulated, whereas rTMS induces long-lasting effects of nerves stimulated. According to the intensity of stimulation, the direction of coil and stimulation frequency, rTMS can increase or decrease the excitability of the corticospinal tract and has been verified as techniques to treat a variety of neuropsychiatric disorders. In rTMS studies using electroencephalogram (EEG), changes in brain waves have been measured before and after TMS or simultaneously during TMS. In these studies, low frequency (< or =1 Hz) rTMS, high-frequency (5-25 Hz) rTMS, theta burst stimulation, paired association stimulation have been studied and somatosensory, visual, cognitive, and motor potentials and oscillatory activities were measured and compared before and after TMS. Combined with neurophysiological and, neuroimaging methods, TMS techniques could be used to study cortical excitability, cortical inhibition and excitement, and the cortical plasticity of local areas and neural network. In particular, because simultaneous measurement during TMS as well as measurement before and after TMS is possible, EEG could be very useful to determine the effects of TMS compared to other brain imaging tools.