| Research Abstract |
We examined which components of somatosensory evoked potentials (SEP) were modulated during the voluntary movement of stimulated fingers. Moreover we examined changes in somatosensory evoked potentials (SEPs) during voluntary movement of fingers innervated by the stimulated nerve and those not innervated by the stimulated nerve and the relationship of the kind of movement modality. We discuss our findings with respect to the decrease in SEPs in terms of both centrifugal and centripetal mechanisms. We found that N20-P25 (P22 at frontal area) -N35- (N30 at frontal) P45 (P40 at frontal area) components at the F3, the C3'and the P3 were consistently evoked, but we found N35 enhancement at P3 and N30 attenuation at F3 during a sustained voluntary movement. Furthermore, the present experiments showed that fontal N30 was markedly decreased during a sustained voluntary movement. We also found that all SEPs components, except for parietal N35, were significantly decreased during sustained volun
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tary movement tasks. Accordingly, we concluded that the suppression of SEPs appeared to be due to the interaction of both centrifugal and centripetal mechanisms. Namely, in a particular type of movement task, more pronounced efferent mechanisms may contribute to the decrease in SEPs, while in the other types of tasks, more pronounced afferent activities may contribute to the decrease in SEPs. Results showed that the amplitude of most components at F3, C3', and P3, except for P45 at C3, N35 and P45 at P3, , decreased during voluntary finger movement tasks. Further, we found that the components of P40 at F3, P45 at C3', and N35 at P3 were increased during the voluntary pulling movement of the 2nd and the 3rd digits compared to those during the voluntary pushing movement of the 4th and the 5th digits, whereas all other components were decreased at F3, C3', and P3. We also found that not all components of SEPs were decreased while some SEPs in middle latency were increased. We confirmed the selectivity in attenuation of the SEPs. Less
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