title: Complementary activation of the ipsilateral primary motor cortex during a sustained handgrip task.
abstract: OBJECTIVE
  Near-infrared spectroscopy (NIRS) can be used to examine bilateral motor cortex activation during a sustained motor task in brain areas where increased oxygenation reflects cortical activation. This study examines the time course of activation of the bilateral motor cortex during a moderate-intensity handgrip task.
  
  
  METHODS
  Ten healthy right-handed male subjects participated in this study. Functional NIRS probes were placed over the cortex to measure motor cortical activations while the subjects performed a 180-s handgrip task incrementally [30-60% of the maximal voluntary contraction (MVC) at 0.17% increase/s]
  
  
  RESULTS
  Contralateral primary motor cortex (ContraM1) oxygenation values significantly increased from baseline between 40 and 120 s after the start of the motor task (p < 0.05). Moreover, the ipsilateral primary motor cortex (IpsiM1) oxygenation values significantly increased from baseline between 140 and 180 s after the start of the motor task (p < 0.05). IpsiM1 oxygenation gradually increased from 140 to 180 s, whereas ContraM1 oxygenation gradually decreased from 120 to 180 s after the start of the motor task.
  
  
  CONCLUSIONS
  These results suggest that the complementary functions of IpsiM1 become activated in response to the working of the ContraM1 during a continuous handgrip task.
authors.affiliation: Department of Health and Nutrition, Niigata University of Health and Welfare, 1398 Shimami-chi, Kita-ku, Niigata, 950-3198, Japan. shibuya@nuhw.ac.jp.|Center for General Education, Nagasaki Institute of Applied Science, 536 Aba, Nagasaki, 851-0193, Japan. shibuya@nuhw.ac.jp.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Shibuya
authors.affiliation: Faculty of Business Administration, Osaka University of Commerce, 4-1-10 Mikuriyasakae-machi, Higashi-Osaka, 577-8505, Japan.
authors.forename: Naomi
authors.initials: N
authors.lastname: Kuboyama
authors.affiliation: Center for General Education, Nagasaki Institute of Applied Science, 536 Aba, Nagasaki, 851-0193, Japan.
authors.forename: Seigo
authors.initials: S
authors.lastname: Yamada
mesh_terms: D000328:Adult; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006225:Hand / Q000502:physiology*; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D010108:Oxyhemoglobins / Q000378:metabolism; D019265:Spectroscopy, Near-Infrared / Q000379:methods; D055815:Young Adult
chemical_list: D010108:Oxyhemoglobins
keywords: Force modulation; Interhemispheric interaction; Motor cortex; Movement