Transcranial magnetic stimulation at the interface with other techniques: a powerful tool for studying the human cortex.

Transcranial magnetic stimulation (TMS) has developed into a very powerful tool in the hands of basic and clinical neuroscientists alike to study function and dysfunction of the human brain noninvasively and painlessly. However, as a stand-alone technique, the potential of TMS to gain knowledge is relatively limited. This potential can be strongly enhanced by combining TMS with simultaneous measurements in other electrophysiological (EEG) or imaging modalities (PET, fMRI, NIRS, MRS) or by combining TMS with exposure to neuroactive drugs (pharmaco-TMS). This review provides an up-to-date synopsis of these combined approaches and highlights important examples that have advanced our understanding of how TMS interacts with neuronal networks in the human brain.