Transcranial magnetic stimulation is a type of non-invasive brain stimulation, whereby a brief electrical current is generated within the cerebral cortex. This electrical pulse is generated by sending a current through a coil held at a predetermined position on the scalp, and the resulting magnetic field then generates an electrical pulse within the brain, at a depth of up to several centimetres below the skull (1).

By targeting and disrupting neural activity at specific locations of the cerebral cortex, TMS has
been used to study aspects of cognitive and perceptual activity related to localization of function in cortical areas of the brain. The technique is also used to treat some patients suffering from medication-resistant depression, as well as in the establishment of cortical motor and language maps prior to surgical interventions (2).

Sources:

1. Cowey A. The Ferrier Lecture 2004 : What can transcranial magnetic stimulation tell us about how the brain works? Philos Trans R Soc Lond B Biol Sci. 2005 Jun 29;360(1458):1185-205.

2. Rotenberg, A., Horvath, J.C. & Pascual-Leone, A. (Eds.). (2016). NeuroMethods: Transcranial Magnetic Stimulation. New York: Springer Publishing Company, vii