The aim of this study was to investigate the changes in movement-related cortical potential preceding voluntary muscle relaxation handgrip task. The subjects were nine healthy persons (means 24.2 years of age) who were right-handed. Before the experiments, maximum voluntary contraction (MVC) of the dominant hand was measured for all subjects. The subjects performed three relaxation tasks with the right hand (dominant): After the subjects maintained 30%MVC for at least 5 sec, they performed relaxation from 30%MVC to 0%MVC (Task 1), at 10%MVC (Task 2), and at 20%MVC (Task 3). The MRCP amplitudes at Task 2 and 3 were significantly larger than that of handgrip Task 1. The MRCP onsets at Task 2 and 3 were significantly earlier than that of handgrip Task 1. These findings suggest that there was a difference in neural preparation between voluntary muscle relaxation and precisely controlled force relaxation.

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[in Japanese]

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[in Japanese]

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