Abstract
The purpose of the present study was to investigate the short latency motor response of the swallowing-related muscles evoked by the transcranial magnetic stimulation of the trigeminal nerve. The subjects were 10 healthy humans aged between 18 and 37. Magnetic stimulation was delivered to the cranial nerve through the scalp, and the EMG responses were recorded from the suprahyoid muscle complex. The EMG responses were effectively evoked when the center of the round coil was at the locus 8.8-12.5 cm lateral and -1.5-3.6 cm posterior to the vertex. The latencies of the EMG responses were between 3.5 and 5.6 ms. The precise locus of the stimulation evoking the EMG responses was searched for using a figure-eight-shaped coil, and it was found that the EMG responses were most effectively evoked when the hot spot of the coil was at the locus 14-16 cm lateral and 4-6 cm posterior to the vertex, and when the induced current flow was posteriorly directed in the brain. This technique should be applicable for investigating the swallowing-related motor system.
