Task-dependent effects evoked by foot muscle afferents on leg muscle activity in humans

Michele Abbruzzese, Vitoantonio Rubino, Marco Schieppati

Research output: Contribution to journalArticlepeer-review

Abstract

The effect of low intensity electrical stimulation of the posterior tibial nerve (PTN) at the ankle on the active triceps surae (TS) muscles was studied in normal subjects, both in a prone position and while standing. PTN stimulation regularly evoked the I-I-reflex in the flexor digitorum brevis and, in the prone position, a short-latency facilitatory effect in the soleus muscle. During standing, the facilitatory effect was preceded by a clear-cut reduction in electromyograph (EMG) activity. The inhibition-facilitation sequence was evoked in the gastrocnemii under both conditions, on average, though individual differences were present. An EMG modulation similar to that observed under standing conditions was present also in the prone position when subjects pressed the sole of the foot against the wall. Stimulation of sural or digital nerves did not evoke similar effects. It is concluded that foot muscle afferents establish oligosynaptic connections transmitting mixed effects to the TS motoneuronal pool, and that contact with the sole of the foot plays an enabling role for the inhibitory pathway directed to the soleus muscle.

Original languageEnglish
Pages (from-to)339-348
Number of pages10
JournalElectroencephalography and Clinical Neurophysiology - Electromyography and Motor Control
Volume101
Issue number4
DOIs
Publication statusPublished - Aug 1996

Keywords

  • Cutaneous modulation
  • Human
  • Proprioception
  • Reflexes
  • Synergistic muscles

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)

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