Concurrent fNIRS and transcranial magnetic stimulation (TMS) allows for direct investigation of cortical brain activation and connectivity. Moreover, the effects of repetitive TMS (rTMS) in distinct brain regions without quantifiable behavioral changes can be objectively measured through fNIRS.
Since fNIRS does not use of electrical (nor magnetic) fields, it is suitable to be combined with TMS without particular technical precautions. Furthermore, as NIRS is an optical signal, the strong magnetic fields generated during TMS do not cause artifacts or interference in the NIRS data. The TMS coil may therefore be placed directly over NIRS probes, making it possible to measure hemodynamic changes directly under the stimulated site.