title: Functional near-infrared spectroscopy study on primary motor and sensory cortex response to clenching.
abstract: The purpose of this study was to elucidate the influence of clenching and clenching intensity on oxygenated hemoglobin (OxyHb) levels in regional cerebral blood flow as an indicator of brain activity in the primary motor and sensory cortices. Functional near-infrared spectroscopy (fNIRS) was used to minimize the effect of clenching-associated muscle activity in eight healthy subjects. Subjects were required to clench at 20%, 50% and 80% of maximum clenching force. To minimize the effect of temporal muscle activity on the working side of the jaw, the fNIRS probes were positioned contralaterally, in the left temporal region. Activation of the primary motor and sensory cortices with clenching was noted in all subjects, irrespective of intensity of clenching. A significant increase was observed in OxyHb in the primary motor cortex between at 80% and both 20% and 50% clenching intensity. In the primary sensory cortex, OxyHb showed a significant increase between all levels of clenching intensity. The results suggest that clenching elicits activation of both the primary motor and sensory cortices, and that intensity of clenching influences activation levels in the brain.
authors.affiliation: Department of Sports Dentistry, Tokyo Dental College, Mihama-ku, Chiba-shi, Chiba 261-8502, Japan. sibusawa@tdc.ac.jp
authors.forename: Mami
authors.initials: M
authors.lastname: Shibusawa
authors.forename: Tomotaka
authors.initials: T
authors.lastname: Takeda
authors.forename: Kazunori
authors.initials: K
authors.lastname: Nakajima
authors.forename: Keiichi
authors.initials: K
authors.lastname: Ishigami
authors.forename: Kaoru
authors.initials: K
authors.lastname: Sakatani
mesh_terms: D000328:Adult; D001732:Bite Force; D001931:Brain Mapping / Q000379:methods; D002560:Cerebrovascular Circulation / Q000502:physiology*; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007568:Jaw / Q000502:physiology; D008297:Male; D008410:Masticatory Muscles / Q000294:innervation / Q000502:physiology*; D009044:Motor Cortex / Q000033:anatomy & histology / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D010108:Oxyhemoglobins / Q000032:analysis / Q000378:metabolism; D013003:Somatosensory Cortex / Q000033:anatomy & histology / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D015854:Up-Regulation / Q000502:physiology; D055815:Young Adult
chemical_list: D010108:Oxyhemoglobins