title: Movement-related cortical magnetic fields associated with self-paced tongue protrusion in humans.
abstract: Sophisticated tongue movements are coordinated finely via cortical control. We elucidated the cortical processes associated with voluntary tongue movement. Movement-related cortical fields were investigated during self-paced repetitive tongue protrusion. Surface tongue electromyograms were recorded to determine movement onset. To identify the location of the primary somatosensory cortex (S1), tongue somatosensory evoked fields were measured. The readiness fields (RFs) over both hemispheres began prior to movement onset and culminated in the motor fields (MFs) around movement onset. These signals were followed by transient movement evoked fields (MEFs) after movement onset. The MF and MEF peak latencies and magnitudes were not different between the hemispheres. The MF current sources were located in the precentral gyrus, suggesting they were located in the primary motor cortex (M1); this was contrary to the MEF sources, which were located in S1. We conclude that the RFs and MFs mainly reflect the cortical processes for the preparation and execution of tongue movement in the bilateral M1, without hemispheric dominance. Moreover, the MEFs may represent proprioceptive feedback from the tongue to bilateral S1. Such cortical processing related to the efferent and afferent information may aid in the coordination of sophisticated tongue movements.
authors.affiliation: Department of Oral Physiology, Graduate School of Dental Medicine Hokkaido University, Kita-ku, Sapporo, Hokkaido 060-8586, Japan. Electronic address: maezawa@den.hokudai.ac.jp.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Maezawa
authors.affiliation: School of Dental Medicine, Hokkaido University, Kita-ku, Sapporo, Hokkaido 060-8586, Japan.
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Oguma
authors.affiliation: Department of Oral Physiology, Graduate School of Dental Medicine Hokkaido University, Kita-ku, Sapporo, Hokkaido 060-8586, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Hirai
authors.affiliation: Department of Oral Physiology, Graduate School of Dental Medicine Hokkaido University, Kita-ku, Sapporo, Hokkaido 060-8586, Japan.
authors.forename: Kazunari
authors.initials: K
authors.lastname: Hisadome
authors.affiliation: Department of Pediatrics, Graduate School of Medicine, Hokkaido University, Kita-ku, Sapporo 060-8638, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Shiraishi
authors.affiliation: Department of Oral Physiology, Graduate School of Dental Medicine Hokkaido University, Kita-ku, Sapporo, Hokkaido 060-8586, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Funahashi
mesh_terms: D000328:Adult; D000818:Animals; D001931:Brain Mapping; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D060526:Magnetic Fields; D015225:Magnetoencephalography / Q000379:methods; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D013003:Somatosensory Cortex / Q000502:physiology; D014059:Tongue / Q000502:physiology*; D055815:Young Adult
keywords: Hypoglossal motor nucleus; Magnetoencephalography; Meg; Motor fields; Readiness fields; Voluntary movement