Kenichi Shibuya1,2, Naomi Kuboyama3, Seigo Yamada4. 1. Department of Health and Nutrition, Niigata University of Health and Welfare, 1398 Shimami-chi, Kita-ku, Niigata, 950-3198, Japan. shibuya@nuhw.ac.jp. 2. Center for General Education, Nagasaki Institute of Applied Science, 536 Aba, Nagasaki, 851-0193, Japan. shibuya@nuhw.ac.jp. 3. Faculty of Business Administration, Osaka University of Commerce, 4-1-10 Mikuriyasakae-machi, Higashi-Osaka, 577-8505, Japan. 4. Center for General Education, Nagasaki Institute of Applied Science, 536 Aba, Nagasaki, 851-0193, Japan.
Abstract
PURPOSE: 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. CONCLUSION: These results suggest that the complementary functions of IpsiM1 become activated in response to the working of the ContraM1 during a continuous handgrip task.
PURPOSE: 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. CONCLUSION: These results suggest that the complementary functions of IpsiM1 become activated in response to the working of the ContraM1 during a continuous handgrip task.
Keywords:
Force modulation; Interhemispheric interaction; Motor cortex; Movement