Calibrating balance perturbation using electrical stimulation of the vestibular system

Area of Science:

• Neuroscience
• Biomechanics
• Human Physiology

Background:

• Galvanic vestibular stimulation (GVS) challenges the balance control system by disrupting vestibular inputs.
• Assessing the minimum safe GVS level for maximum balance degradation is crucial for research and clinical applications.

Purpose of the Study:

• To propose an objective method for assessing individual variability in the minimum GVS level (KNEE) that induces maximal balance impairment.
• To establish a standardized approach for balance testing using GVS.

Main Methods:

• Thirteen healthy young subjects stood with eyes closed on a compliant foam surface.
• Postural stability variables were quantified under varying GVS amplitudes (0-4.5 mA).
• The KNEE level was determined by identifying the point of linear relationship between GVS intensity and balance performance decrements.

Main Results:

• A linear relationship was observed between GVS intensity and postural response decrements up to the KNEE level.
• Individual KNEE levels varied between 1-2.5 mA across subjects.
• GVS at the KNEE level caused significant average performance decrements (27-99%) in six stability variables.

Conclusions:

• Individual differences in balance response to GVS are significant.
• The proposed method allows for consistent maximal impairment across subjects using minimal GVS intensity, reducing adverse effects.
• Findings have implications for GVS-based balance testing and training paradigms.