Using the TMS-induced Motor-evoked potential to evaluate the neurophysiology of psychiatric disorders

Abstract

This article reviews studies carried out on the role of transcranial magnetic stimulation (TMS) as an important neurophysiological tool to assess a variety of cortical neurophysiological processes including excitability, inhibition, and plasticity. It discusses how TMS has helped to enhance the understanding of the neurobiology and the treatment of a variety of psychiatric disorders including schizophrenia (SCZ), major depressive disorder (MDD), bipolar disorder (BD), obsessive-compulsive disorder (OCD), and Tourette's disorder (TD). The findings from these studies demonstrate that TMS is a useful tool to evaluate several neurophysiological processes that may be altered in psychiatric illness. Evidence suggests that disorders including SCZ, MDD, BD, and OCD may, in part, be associated with deficient inhibition, altered cortical excitability, and disrupted neural plasticity. Evidence also suggests that psychotropic medications alter the mechanisms, often in a direction opposite to that of illness, thus reflecting on some of their therapeutic effects.