Assessment of vestibulocortical interactions during standing in healthy subjects

PLoS One. 2020 Jun 4;15(6):e0233843. doi: 10.1371/journal.pone.0233843. eCollection 2020.


The vestibular system is essential to produce adequate postural responses enabling voluntary movement. However, how the vestibular system influences corticospinal output during postural tasks is still unknown. Here, we examined the modulation exerted by the vestibular system on corticospinal output during standing. Healthy subjects (n = 25) maintained quiet standing, head facing forward with eyes closed. Galvanic vestibular stimulation (GVS) was applied bipolarly and binaurally at different delays prior to transcranial magnetic stimulation (TMS) which triggered motor evoked potentials (MEPs). With the cathode right/anode left configuration, MEPs in right Soleus (SOL) muscle were significantly suppressed when GVS was applied at ISI = 40 and 130ms before TMS. With the anode right/cathode left configuration, no significant changes were observed. Changes in the MEP amplitude were then compared to changes in the ongoing EMG when GVS was applied alone. Only the decrease in MEP amplitude at ISI = 40ms occurred without change in the ongoing EMG, suggesting that modulation occurred at a premotoneuronal level. We further investigated whether vestibular modulation could occur at the motor cortex level by assessing changes in the direct corticospinal pathways using the short-latency facilitation of the SOL Hoffmann reflex (H-reflex) by TMS. None of the observed modulation occurred at the level of motor cortex. Finally, using the long-latency facilitation of the SOL H-reflex, we were able to confirm that the suppression of MEP at ISI = 40ms occurred at a premotoneuronal level. The data indicate that vestibular signals modulate corticospinal output to SOL at both premotoneuronal and motoneuronal levels during standing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Electromyography / methods*
  • Evoked Potentials, Motor / physiology
  • Female
  • Functional Laterality / physiology
  • H-Reflex / physiology
  • Healthy Volunteers
  • Humans
  • Male
  • Motor Cortex / physiology
  • Motor Neurons / physiology
  • Muscle, Skeletal / physiology
  • Pyramidal Tracts / physiology*
  • Standing Position*
  • Transcranial Direct Current Stimulation
  • Transcranial Magnetic Stimulation
  • Vestibule, Labyrinth / physiology*
  • Young Adult

Grants and funding

This research is supported by the National Science and Engineering Research Council (NSERC) grant to DB. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.