Transcranial magnetic stimulation in neurology: A review of established and prospective applications.

Transcranial magnetic stimulation (TMS) is a neurophysiologic technique to noninvasively induce a controlled current pulse in a prespecified cortical target. This can be used to transiently disrupt the function of the targeted cortical region and explore causal relations to behavior, assess cortical reactivity, and map out functionally relevant brain regions, for example during presurgical assessments. Particularly when applied repetitively, TMS can modify cortical excitability and the effects can propagate trans-synaptically to interconnected cortical, subcortical, and spinal cord regions. As such, TMS can be used to assess the functional integrity of neural circuits and to modulate brain activity with potential therapeutic intent.