Complementary activation of the ipsilateral primary motor cortex during a sustained handgrip task

• Published in: European journal of applied physiology Vol. 116; no. 1; pp. 171 - 178
• Main Authors: Shibuya, Kenichi, Kuboyama, Naomi, Yamada, Seigo
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.01.2016; Springer Nature B.V
• Subjects: Adult; Biomedical and Life Sciences; Biomedicine; Female; Functional Laterality - physiology; Hand - physiology; Hand Strength - physiology; Hemoglobin; Human Physiology; Humans; Magnetic resonance imaging; Male; Motor Cortex - physiology; Movement - physiology; Muscle Contraction - physiology; Muscle, Skeletal - physiology; Occupational Medicine/Industrial Medicine; Original Article; Oxygen Consumption - physiology; Oxyhemoglobins - metabolism; Spectroscopy, Near-Infrared - methods; Spectrum analysis; Sports Medicine; Young Adult; Japan; Interhemispheric interaction; Movement; Force modulation; Motor cortex
• ISSN: 1439-6319; 1439-6327; 1439-6327
• DOI: 10.1007/s00421-015-3262-1

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.