Proprioceptive vibratory stimulation modulates cortico-muscular postural response

For decades, postural control has been believed to be dominated by reflexive mechanisms, but more recent evidence characterizes it as an articulate system which relies on multisensory integration (vestibular, visual, proprioceptive) and cortical coordination to preserve balance in the wake of external disruptions to the quiet stance. Corrective strategies to stabilise the body’s center of mass and prevent falls are planned at the central nervous system level and executed through the modulation of muscular activity, especially in the lower legs muscles: gastrocnemius, soleus and tibialis. In this study, we use localized proprioceptive vibratory stimulation to induce a perturbation of the subjects’ quiet stance. By integrating traditional force plate data with electrophysiological signals (EEG and EMG), we use cortico-muscular and inter-muscular coherence to investigate how brain and muscles interact to shape an effective response to a postural challenge. Our results show how the cortical drive is enhanced in beta [13-30]Hz and gamma [30-45]Hz bands, specifically for the soleus and gastrocnemius muscles, during the task execution. We also reveal a remodulation of the lower legs muscle network, with a distributed strengthening of muscle activity coupling.