Abstract
Brain activities related to jaw movement were investigated to clarify the cortical control mechanisms from the standpoint of relationships between the type of mandibular movement and the appearance of magnetic fields in the primary sensorimotor cortex using magnetoencephalography (MEG) measurements. Three adult volunteers were asked to conduct movements such as jaw opening, lateral jaw, and finger abductive movements. Motor fields (MF) accompanying jaw opening appeared at bilateral primary sensorimotor cortices, while MF related to lateral jaw and unilateral forefinger abductive movements dominantly appeared in the hemisphere contralateral to the movement side. Further, movement evoked fields (MEF) accompanying jaw opening and lateral jaw movement appeared at bilateral primary sensorimotor cortices, while MEF accompanying unilateral forefinger abductive movement appeared in the hemisphere contralateral to the movement side. Forward dipole of MF was estimated at the primary motor cortex, while backward dipole of MEF was estimated at the primary somatosensory cortex in every session. From these findings, it was assumed that the dominance of activity at the primary motor cortex depends on the direction of mandibular movement, and the proprioceptive feedback afferentation accompanying jaw movements to the primary somatosensory cortex would arise from bilateral orofacial regions.
