Magnetoencephalographic representation of the periodontal sensation from bilateral maxillary permanent canine teeth in human primary somatosensory cortex

摘要

In the human primary somatosensory (S1) cortex (the somatosensory homunculus), the somatotopic representation area of periodontal sensation of a tooth has not been elucidated. The present study aimed to determine the somatotopic representation of the periodontal mechanical sensation in the S1. The neuromagnetic responses in cerebral cortex activated by periodontal mechanical sensation on the right and left side were compared. The somatosensory evoked magnetic fields (SEFs) following the mechanical stimulation for the maxillary permanent canines on both sides were measured in five healthy volunteers using a 306-channel whole-head DC-SQUID neuromagentometer (MEG). The N{sub}2 gas pressure driven tapping stimulation was used for mechanical stimulation and applied to the crown surface of the teeth. The stimulator-head was fixed by resin removable retaining appliance. In all the subjects, early components of the SEFs within 100ms following the unilateral stimulation were consistently recorded and are distinguishable into three peaks based on their latencies; 20, 60, and 100ms. The equivalent current dipoles (ECDs) of these components by unilateral stimulation were located on the most lateral part of the posterior part of the central sulcus. These results indicated that the topographic localization of the "periodontal area" in S1 was present in the lower part of the face area in S1, where was previously identified in the post-central gyrus following electrical stimulation of the face.