title: Repeated tongue lift movement induces neuroplasticity in corticomotor control of tongue and jaw muscles in humans.
abstract: This study investigated the effect of repeated tongue lift training (TLT) on the excitability of the corticomotor representation of the human tongue and jaw musculature. Sixteen participants performed three series of TLT for 41 min on each of 5 consecutive days. Each TLT series consisted of two pressure levels (5 kPa and 10 kPa). All participants underwent transcranial magnetic stimulation (TMS) and electromyographic (EMG) recordings of motor evoked potentials (MEPs) in four sessions: (1) before TLT on Day 1 (baseline), (2) after TLT on Day 1, (3) before TLT on Day 5, and (4) after TLT on Day 5. EMG recordings from the left and right tongue dorsum and masseter muscles were made at three pressure levels (5 kPa, 10 kPa, 100% tongue lift), and tongue, masseter, and first dorsal interosseous (FDI) MEPs were measured. There were no significant day-to-day differences in the tongue pressure during maximum voluntary contractions. The amplitudes and thresholds of tongue and masseter MEPs after TLT on Day 5 were respectively higher and lower than before TLT on Day 1 (P<0.005), and there was also a significant increase in tongue and masseter MEP areas; no significant changes occurred in MEP onset latencies. FDI MEP parameters (amplitude, threshold, area, latency) were not significantly different between the four sessions. Our findings suggest that repeated TLT can trigger neuroplasticity reflected in increased excitability of the corticomotor representation of not only the tongue muscles but also the masseter muscles.
authors.affiliation: Department of Oral Function and Rehabilitation, Nihon University School of Dentistry at Matsudo, 2-870-1, Sakaecho-nishi, Matsudo Chiba 271-8587, Japan; Section of Orofacial Pain and Jaw Function, Aarhus University, Department of Dentistry, Denmark.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Komoda
authors.affiliation: Department of Oral Function and Rehabilitation, Nihon University School of Dentistry at Matsudo, 2-870-1, Sakaecho-nishi, Matsudo Chiba 271-8587, Japan. Electronic address: iida.takashi96@nihon-u.ac.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Iida
authors.affiliation: Section of Orofacial Pain and Jaw Function, Aarhus University, Department of Dentistry, Denmark; Hammel Neurorehabilitation Centre and University Research Clinic, Denmark.
authors.forename: Mohit
authors.initials: M
authors.lastname: Kothari
authors.affiliation: Department of Oral Function and Rehabilitation, Nihon University School of Dentistry at Matsudo, 2-870-1, Sakaecho-nishi, Matsudo Chiba 271-8587, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Komiyama
authors.affiliation: Section of Orofacial Pain and Jaw Function, Aarhus University, Department of Dentistry, Denmark; Scandinavian Center for Orofacial Neuroscience (SCON), Sweden.
authors.forename: Lene
authors.initials: L
authors.lastname: Baad-Hansen
authors.affiliation: Department of Oral Function and Rehabilitation, Nihon University School of Dentistry at Matsudo, 2-870-1, Sakaecho-nishi, Matsudo Chiba 271-8587, Japan.
authors.forename: Misao
authors.initials: M
authors.lastname: Kawara
authors.affiliation: Department of Oral Physiology, Faculty of Dentistry, University of Toronto, Toronto, Canada; Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Canada.
authors.forename: Barry
authors.initials: B
authors.lastname: Sessle
authors.affiliation: Section of Orofacial Pain and Jaw Function, Aarhus University, Department of Dentistry, Denmark; Scandinavian Center for Orofacial Neuroscience (SCON), Sweden; Department of Dental Medicine, Karolinska Institutet, Huddinge, Sweden.
authors.forename: Peter
authors.initials: P
authors.lastname: Svensson
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008406:Masseter Muscle / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D013997:Time Factors; D014059:Tongue / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
keywords: Corticomotor control; Neuroplasticity; Tongue lift movement; Transcranial magnetic stimulation