Abstract
Transcranial Magnetic Stimulation (TMS) is a non- invasive method of brain stimulation, inducing eddy current in cerebral cortex by the electromagnetic induction. The eddy current stimulates mainly interneurons, resulting in indirect stimulation of pyramidal neurons. Based on Motor Evoked Potential (MEP), single-and paired-pulse TMS can be used to investigate excitatory and inhibitory regulation mechanisms of motor cortex and also to measure central motor conduction time. Repetitive TMS (rTMS) could have long-lasting effects on neuronal activity, potentially reflecting enhanced neuroplasticity. Thus therapeutic application of rTMS has been studied in neuropsychiatric disorders. Since 1995, antidepressant effect of rTMS has been actively studied as clinical research. In 2008, FDA has finally approved the therapeutic use of rTMS for medication-resistant major depression. In recent meta-analyses of rTMS, it has been reported that antidepressant effects of rTMS could be smaller than those of Electroconvulsive Therapy (ECT), however almost same as those of antidepressants. As novel strategies of rTMS, Theta Burst Stimulation (TBS) and Quadro- Pulse Stimulation (QPS) are expect-ed to have more robust long-lasting effects on neuronal activity than conventional rTMS.
