| Project/Area Number |
07680121
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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 |
体育学
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| Research Institution | Yamaguchi University |
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Principal Investigator |
KAWAI Yosuke Yamaguchi University, Faculty of Education, Professor, 教育学部, 教授 (00035148)
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| Co-Investigator(Kenkyū-buntansha) |
MIYATA Hirohumi Yamaguchi University, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (90190793)
MINAGAWA Takashi Yamaguchi University, Faculty of Education, Professor, 教育学部, 教授 (50035143)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1996: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1995: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | motor control / fast motor unit / slow motor unit / monosynaptic EPSPs / Ia afferent / Diters nucleus / slow運動ニューロン / 外側前庭核 / IaEPSP / 膜特性 |
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| Research Abstract |
The present study examined the distributions of the monosynaptic excitatory post synaptic potentials (EPSPs) produced by group Ia afferents and lateral vestibular (Diters) nucleus in type identified medial gastrocnemius (MG) and soleus (Sol) motoneurons, in order to elucidate the role of the different type of motor units in motor control.
Experiments were performed on the anethsetized cats. Glass microelectrodes were used for intracellular stimulating and recording procedures. Motor units of MG and Sol muscles were classfied into three categories ; types FF,FR and S,using three physiological criteria (twitch contraction time, sag property and fatigue index).
The maximum amplitudes of monosynaptic EPSPs resulting from stimulation of Ia afferents (Ia EPSPs) were related to motor unit type, that is, largest in type S units, somewhat small in type FR units and smallest in type FF units. The amplitudes of Ia EPSPs were clearly correlated to the duration of AHP or twitch contraction time, but not soma diameter.
There was weak correlation between the amplitudes of monosynaptic EPSPs produced by Diters nucleus (DN-EPSPs) and the duration of AHP in MG motoneurons. In Sol motoneurons, positive correlation were observed between the amplitudes and the rise time of monosynaptic DN-EPSPs. Facilitation of the amplitudes of monosynaptic DN-EPSPs was observed when double stimulation were applied. There was no correlation between the first and second amplitudes of monosynaptic DN-EPSPs.
Above findings show that the maximum amplitudes of Ia EPSPs were clearly related to motor unit type or the duraiton of AHP,however, amplitudes of monosynaptic DN-EPSPs were not clearly related to the electrical properties of motoneurons. These differences might have an important meaning in the motor unit usage.
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