Probing Vestibular Function With Frequency- Modulated Electrical Vestibular Stimulation

Area of Science:

• Neuroscience
• Biophysics
• Bioengineering

Background:

• Electrical vestibular stimulation (EVS) is a non-invasive method to modulate the vestibular system, influencing balance and perceived motion.
• Understanding the relationship between EVS parameters and physiological responses is crucial for its application and safety.

Purpose of the Study:

• To investigate the strength-frequency dependency of frequency-modulated EVS (FM-EVS) on center-of-pressure (CoP) responses.
• To estimate the highest effective frequencies of EVS at different current intensities.
• To determine the in situ electric field strength in the vestibular system and response latency.

Main Methods:

• FM-EVS using linear chirp waveforms was applied to ten subjects.
• Center-of-pressure (CoP) responses were measured to assess balance perturbations.
• Finite element method modeling using 15 anatomical head models estimated the in situ electric field.

Main Results:

• CoP responses were evoked at frequencies up to 5.5 ± 1.1 Hz (0.75 mA), 8.2 ± 1.1 Hz (1.0 mA), and 10.5 ± 1.2 Hz (1.5 mA).
• The vestibular electric field strength was estimated at 175 ± 23 mV/m per 1 mA current.
• Average response latency was 86 ± 17 ms.

Conclusions:

• EVS effectiveness in eliciting balance responses is frequency and intensity-dependent.
• The findings provide essential data for developing human electromagnetic field exposure guidelines.
• Results inform the design of EVS and transcranial electrical brain stimulation studies.