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Localization of transcranial magnetic stimulation

**Figure:** Transcranial magnetic stimulation of the visual cortex, from Potts [123].
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Transcranial magnetic stimulation (TMS) consists of applying a focal magnetic field on specific parts of the brain in order to induce motor or sensitive responses. TMS has been extensively used in research in order to map the brain functions, for instance by Brasil-Neto [16] for the motor cortex. It has also been used for therapeutic purposes, such as the treatment of depression by George [66].
Initial TMS studies used cranial landmarks to define the locations of the stimulation, which does not take into account the individual variability in cortical morphology. Recently, Potts [123] has used a 3D optical tracking system to register TMS with the individual's MRI. This allows to locate the stimulation precisely on both the scalp and the cortical surface, as illustrated at figure

for a study of the inhibition of the visual stimulus.

Olivier Cuisenaire
1999-10-05