Sensory supplementation system based on electrotactile tongue biofeedback of head position for balance control

TL;DR

This study demonstrates that a tongue-based electrotactile biofeedback system providing head position information can improve postural stability during quiet standing, especially when somatosensory input from the support surface is compromised.

Contribution

It introduces a novel electrotactile tongue biofeedback system that enhances balance control by conveying head orientation information to the user.

Findings

Biofeedback reduced CoP displacements on Foam surface.

Artificial head orientation info aids balance under altered somatosensory conditions.

System supports sensory re-weighting for improved postural control.

Abstract

The present study aimed at investigating the effects of an artificial head position-based tongue-placed electrotactile biofeedback on postural control during quiet standing under different somatosensory conditions from the support surface. Eight young healthy adults were asked to stand as immobile as possible with their eyes closed on two Firm and Foam support surface conditions executed in two conditions of No-biofeedback and Biofeedback. In the Foam condition, a 6-cm thick foam support surface was placed under the subjects' feet to alter the quality and/or quantity of somatosensory information at the plantar sole and the ankle. The underlying principle of the biofeedback consisted of providing supplementary information about the head orientation with respect to gravitational vertical through electrical stimulation of the tongue. Centre of foot pressure (CoP) displacements were recorded using a force platform. Larger CoP displacements were observed in the Foam than Firm conditions in the two conditions of No-biofeedback and Biofeedback. Interestingly, this destabilizing effect was less accentuated in the Biofeedback than No-biofeedback condition. In accordance with the sensory re-weighting hypothesis for balance control, the present findings evidence that the availability of the central nervous system to integrate an artificial head orientation information delivered through electrical stimulation of the tongue to limit the postural perturbation induced by alteration of somatosensory input from the support surface.