運動課題中の手がかりの違いが体性感覚の入力量と運動技能に及ぼす影響

抄録

Exercise therapy for tactile disorders is yet to be established. It is believed that motor therapy for tactile dysfunction should be based on tasks that require cue identification. However, the difficulty level of the cues to be identified has not yet been clarified. In this study, we investigated the effects of different tactile cues on somatosensory input and motor skills using somatosensory evoked potentials (SEPs). Participants were 20 healthy adults (mean age 26.1 ± 3 years). The exercise task consisted of 120 repetitions of palmar abduction of the thumb at a frequency of 1 Hz within a range of 20°.The practice conditions were the no-cue condition and 0.1 mm and 0.6 mm conditions with different cue heights. Motor skills were evaluated from the mean absolute error of 20° palmar abduction before and after practice and from the coefficient of variation of the palmar abduction movement. SEPs were recorded by stimulating the median nerve on the dominant hand before, during and after practice. The SEP amplitudes of N9, N13, and N20 were analyzed. The Friedman test and Bonferroni-corrected Wilcoxon's signed rank sum test were used for the statistical comparison of SEP amplitudes and motor skills in the three conditions. N9 and N13 amplitudes showed no differences in any of the three conditions. The N20 amplitude during the practice task showed no differences under any of the conditions. The mean absolute error from 20°-did not change before, during, or after practice in the no-cue condition. No change was observed in the motor skills before and after practice in any of the three conditions. Gating during exercise is said to select the necessary somatosensory information. In the present study, there was no change in N20 amplitude during practice in all conditions. We hypothesized that this was due to different gating mechanisms at work in each condition. The lack of change in motor skills was considered to be caused by the lack of practice frequency. The lack of improvement in motor skills due to the insufficient number of practice sessions could have caused the lack of change in SEP amplitude after practice.