Influence of Voluntary Muscle Contraction on the Duration of the Silent Period Evoked by Transcranial Magnetic Stimulation

Introduction: It is known that the duration of the silent period (SP) following transcranial magnetic stimulation (TMS) can be used as a measure of intracortical inhibition. Thus, the SP is used in the clinical routine and in many studies, e.g., in order to evaluate the prognosis of motor recovery after stroke or for examining the cortical excitability in epilepsy patients. In most studies using TMS, recordings of the SP are performed by asking the subjects to contract their muscles (e.g., the first dorsal interosseous muscle, FDI) with maximal or sub-maximal strength. However, a possible modulation of the SP de…