Changes in central motor-sensory system following voluntary movement of stimulated finger

We examined which components of somatosensory evoked potentials (SEP) were modulated during the voluntary movement of stimulated fingers and discuss our findings with respect to the decrease in SEPs in terms of both centrifugal and centripetal mechanisms.

The study was performed in the Laboratory of Physiology, Institute of Health and Sport Sciences, University of Tsukuba. Experiments were performed on 10 healthy young male subjects, aged 19-21 years. All subjects were right-handed and were free of neurological disease.

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 N35 was increased at P3 and N30 attenuation at F3 during a sustained voluntary movement. Furthermore, the present experiments showed that frontal N30 was markedly decreased during a sustained voluntary movement. We also found that all SEPs components, except for parictal N35, were significantly decreased during sustained voluntary movement tasks.

We concluded that the suppression of SEPs appeared to be due to the interaction of both centrifugal and centripatal mechanisms. Namely, in a particular type of movement task, more prenounced afferent 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.