Transcranial magnetic stimulation and the human brain.
Brief overview. Barker, et al. (1985) first used it. TMS does not affect corticospinal neurons directly but rather synaptic inputs. Visual system: may produce phosphenes or erase brieft stimuli, may interfere with motion perception. SMA TMS impairs accuracy of complex finger movements, only sequence elements executed somewhat later than the TMS (Gerloff et al., 1997). Speech arrest. Brain plasticity: after arm amputations the representaion shrinks, in Braille readers the representations grows, also following piano practice. B.g. disorder seems to reduce cortical inhibition. rTMS (> 5 Hz) can have lasting enhancement of motor excitability (cf. long-term potentiation LTP), slow rTMS (1 Hz) will transiently depress excitability. rTMS may affect mood after TMS of left dorsolateral prefrontal cortex. High frequency rTMS may cause seizures.