Neural interference effects on lateral vestibulospinal tract excitability by noisy galvanic vestibular stimulation

Noisy galvanic vestibular stimulation (GVS) using weak random noise waveforms enhances postural stability by modulating vestibular-related neural networks. This study aimed to investigate the neural interference mechanisms of noisy GVS on lateral vestibulospinal tract (LVST) excitability.

Twenty-six healthy volunteers were randomly divided into two groups: balance training combined with noisy GVS and sham GVS. Participants performed 10-minute balance training while standing on a soft foam surface with their eyes closed while adapting to each electrical stimulus. LVST excitability was assessed by measuring the soleus H-reflex following square-wave pulse GVS. Postural stability was measured by assessing the center of foot pressure sway while standing on a foam surface with eyes closed.

The noisy GVS group showed significantly increased post-intervention H-reflex amplitude. The sham GVS group showed no significant difference in H-reflex amplitude pre- and post-intervention. The average sway velocity in the noisy and sham GVS groups significantly decreased in the medial-lateral direction of the center of foot pressure.

Noisy GVS may enhance LVST excitability and decrease body sway via vestibular system interference during holding upright, which relies heavily on vestibular sensations.

These findings may help understand the neural mechanisms of noisy GVS in neurorehabilitation.