2005 年 5 巻 p. 97-101
The purpose of this study was to investigate electromyographic reaction time (EMG-RT) in auditory stimulus of movements of the non-dominant hand. The comparative items were unilateral auditory stimulus and bilateral auditory stimulus, and alteration of stimulus number. We experimented with 11 right-handed healthy subjects. The subjects extended quickly the left index finger on the non-dominant hand, in response to an auditory stimulus signal. The conditions of auditory stimulus were: stimulus frequency of 0.5 Hz, stimulus intensity of 90 dB, auditory frequency of 1 KHz and nine stimuli per trial. We experimented using an eye mask, in order to remove visual effects. There was no significant difference in the EMG-RT between unilateral auditory stimulus and bilateral auditory stimulus. In the alteration of stimulus number, the EMG-RT from second to ninth auditory stimulus were shorter than the first stimulus; and the EMG-RT from third to ninth auditory stimulus were shorter than the second stimulus. From these results, it was suggested that there was no significant difference between unilateral auditory stimulus and bilateral auditory stimulus, because the experimental task was too easy. With regard to alteration of stimulus number, in the generation of movement up to the second auditory stimulus, stimulus information was propagated to the cerebral cortex through the cerebellum, which converted it to movement. In the generation of movement from the third auditory stimulus onwards, the motivation to movement increased the activity of the circuits linking the basal ganglia to the cortex, suggesting that efficient processing by motor learning took place.