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Transcranial magnetic stimulation

Compared to electrical stimulation that utilizes brief, high-voltage electric shock to activate neurons, which can potentially activate pain fibers, transcranial magnetic stimulation (TMS) was developed by Baker in 1985. TMS uses a magnetic wire above the scalp, which carries a sharp and high current pulse. A time variant magnetic field is induced perpendicular to the coil due to the applied pulse which consequently generates an electric field based on Maxwell 's law. The electric field provides the necessary current for a non-invasive and much less painful stimulation. There are two TMS devices called single pulse TMS and repetitive pulse TMS (rTMS) while the latter has greater effect but potential to cause seizure. TMS can be used for therapy particularly in psychiatry, as a tool to measure central motor conduction and a research tool to study different aspects of human brain physiology such as motor function, vision, and language. The rTMS method has been used to treat epilepsy with rates of 8–25 Hz for 10 seconds. The other therapeutic uses of rTMS include parkinson diseases, dystonia and mood diseases. Also, TMS can be used to determine the contribution of cortical networks to specific cognitive functions by disrupting activity in the focal brain region. Early, inconclusive, results have been obtained in recovery from coma (persistent vegetative state) by Pape et al. (2009).