ABSTRACT
Transcranial magnetic stimulation (TMS) refers to a non-invasive technique introduced in 1985 by Barker and colleagues1 that can be used to transiently induce, change or interfere with neuronal activity in relatively circumscribed brain regions. Studies using electroencephalographic (EEG) monitoring of non-epileptic volunteers before, during and after repetitive transcranial magnetic stimulation (rTMS) generally found no apparent EEG abnormalities that could be attributed to rTMS. A growing number of studies report consistent and relatively long-lasting changes of some of these electromyographic parameters of corticospinal excitability following rTMS. The frequency-dependent modulation of motor cortex excitability by rTMS shows a substantial variability across subjects. Large inter-individual variability does invalidate offline rTMS as a potential therapeutic tool in neurology and psychiatry, but calls for great care in the selection of rTMS parameters for a given patient. The chapter shows that the degree to which language is disrupted by rTMS is significantly determined by the degree of hemispheric language lateralization.
