Abstract
BackgroundDuring voluntary muscle contraction, sensory information induced by electrostimulation of the nerves supplying the contracting muscle is inhibited and the somatosensory evoked potentials (SEPs) amplitude decreases. This depression of sensory input during voluntary muscle contraction has been demonstrated by many studies using electrophysiological methods. However, the association between the electrophysiological response of the sensory system during sustained muscle contraction and subjective peripheral sensation (SPS) is still unclear. The aim of this study was to investigate changes in spinal excitability, SEPs, and SPS during voluntary muscle contraction.ResultsThe appearance rate of the F-wave was significantly higher during muscle contraction than rest, whereas no significant difference was observed in F-wave latency between muscle contraction and rest. Furthermore, the P25 amplitude of SEPs was significantly lower during muscle contraction than rest, whereas the N20 amplitude of SEPs exhibited no significant differences. The SPS was significantly lower during muscle contraction than restConclusionsWe conclude that sensory gating, which is found in the P25 component of SEPs during muscle contraction, is one of the neurophysiological mechanisms underlying the suppression of SPS.
Highlights
During voluntary muscle contraction, sensory information induced by electrostimulation of the nerves supplying the contracting muscle is inhibited and the somatosensory evoked potentials (SEPs) amplitude decreases
The appearance rate of the F-wave was significantly higher during muscle contraction (83.4 ± 12.3%) compared to rest (34.2 ± 16.0%; t (12) = 9.638, P < 0.001; Fig. 1b)
No significant differences in F-wave latency were observed between muscle contraction (26.7 ± 1.7 ms) and rest (27.2 ± 1.8 ms; t (12) = 1.257, P = 0.23; Fig. 1c)
Summary
Sensory information induced by electrostimulation of the nerves supplying the contracting muscle is inhibited and the somatosensory evoked potentials (SEPs) amplitude decreases. This depression of sensory input during voluntary muscle contraction has been demonstrated by many studies using electrophysiological methods. The F-wave appearance rate indicates the number of motor units participating in the waveform [8] and naturally varies at a certain width even in the resting state This natural variation suggests that sensory input influences the effect the central nervous system has on α-motoneurons. The facilitation of spinal α-motoneurons during muscle contraction may occur locally and systemically
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