Magnetic sensory cortical responses evoked by tactile stimulations of the human face, oral cavity and flap reconstructions of the tongue

Magnetoencephalography (MEG) is a procedure that analyzes the magnetic responses of neurons. An MEG system with a 37-channel superconductivity quantum interference device (SQUID) was used to record magnetic signals from the human brain in response to tactile stimulations of the face and oral cavity. Six normal individuals were studied as well as three patients who had undergone hemiglossectomies as treatment for carcinoma of the tongue and reconstruction with a pectoralis major myocutaneous flap. When the locations of the magnetic responses having latencies of 40 ms from onset of tactile stimulation were identified, these corresponded to the primary somatosensory cortex. In patients whose tongues had been reconstructed with a pectoralis major myocutaneous flap, the magnetic response upon stimulation of the flap was recorded in a sensory cortical area identical to that corresponding to the tongue. MEG systems such as the one described permit functional mapping of the cerebral cortex on stimulating the face and oral cavity.