| Project/Area Number |
15500405
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical education
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| Research Institution | Chiba University |
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Principal Investigator |
KOMIYAMA Tomoyoshi Chiba University, Faculty of Education, Professor, 教育学部, 教授 (70215408)
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| Project Period (FY) |
2003 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2004: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2003: ¥900,000 (Direct Cost: ¥900,000)
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| Keywords | motor learning / MEP / motor unit / electromyography / H-reflex / cutaneous reflex / 運動習熟 / 単一運動単位 / 単収縮張力 / 運動後 |
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| Research Abstract |
The present study investigated possible neuromuscular mechanisms underlying short-term improvement of visually-guided force tracking performance. Eighteen healthy volunteers performed slow ramp contractions with index finger abduction (5 % MVC,1 % MVC/sec) under a visually-guided force tracking condition. The amount of electromyographic(EMG) activity in the first interosseus muscle(FDI) showed a gradual decrease with the increasing trial number. In contrast, the magnitude of the motor evoked potential(MEP) elicited by trascranial magnetic stimulation(TMS) did not show a significant change. Investigation of single motor unit(MU) activity recorded with a pair of intramuscular electrodes demonstrated that in 51 of 30 MUs threshold force (F-th) of the MU unit progressively increased with the increasing trial number. A significant decrease in F-th of single MU was detected in 2 MU. There were no systematic changes in the firing rate of MUs which showed an increase in the F-th during the motor task was found. To determine possible changes in muscular force producing mechanisms, changes in the twitch force of single MU was assessed by a spike-triggered averaging technique. In twenty-six of eleven MUs, the twitch force increased more than 20 % after the motor task compared to that under the control condition. Neither the magnitude of H-reflex nor cutaneous reflexes showed a significant change after the motor task compared to those before. These findings suggest that a decrease in number of recuited MUs and potentiation of muscle fibers could play a crucial role in improvement of the performance. It may be that the brain effectively retrieves information concerning concurrent changes in the muscle involved in the motor task, then re-organize the motor program in order to optimize the descending motor output regarding the properties of the muscles.
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