| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1997: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1996: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1995: ¥700,000 (Direct Cost: ¥700,000)
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| Research Abstract |
A biomechanical and neurophysiological analysis of anticipatory postual adjustments associated with the early phase of a voluntary arm movement was carried out in normal subjects. Arm elevation, performed at maximal velocity, was studied with unilateral arm movement in freely and counterbalanced (suspended in a safety harness) standing humans. The ground reaction force of both legs, tengential acceleration of the shank and electromyographic (EMG) activity of the anterior deltoid (AD), biceps femoris (BF) and soleus (Sol) muscles were recorded. Sol H-reflex of both legs were also elicited. In this study, we systematically investigated biomechanical and EMG phenomena that precede and follow the onset of voluntary arm movements. Prior to and during the arm movement (i.e., AD activity), a sequence of EMG modofications occurred in ipsilateral BF and Sol muscles. Those modifications preceding BF activity included silent phases in Sol EMG and depression of Sol H-reflexes. By comparing EMG modifications with depression of the Sol H-reflex, we conclude that Ia and presynaptic inhibitory pathways do not play a specific role in those Sol H-reflex depression. Moreover, because Sol H-reflex depression occurs in both freely standing and counterbalanced postures, anticipatory postural adjustment appear to be preprogramd in the central neuvous systems unrelated to peripheral neural mechanisms. Since changes of EMG activities of ipsilateral BF and Sol appeared simultaneously and Sol H-reflex depressions were dependent on EMG activities of ipsilateral BF,control commands to anticipatory postural adjustment would excite BF and inhibit Sol.
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