# Galvanic vestibular stimulation alters the sense of upright

## TL;DR

Galvanic vestibular stimulation can slightly alter how people perceive their upright body position, with effects linked to brain hemisphere asymmetry.

## Contribution

The study reveals that right-sided anodal GVS affects upright perception more than left-sided stimulation, suggesting hemispheric asymmetry in vestibular processing.

## Key findings

- Right-sided anodal GVS significantly altered the Subjective Postural Vertical in both age groups.
- Left-sided anodal GVS had no significant effect on perceived upright body orientation.
- The observed changes were small and not due to reduced sensitivity to body verticality.

## Abstract

Given the vestibular system’s important role in the perception of upright, we investigated the possible effects of galvanic vestibular stimulation (GVS) on the perception of one’s own upright body orientation in relation to gravity, the so-called ‘Subjective Postural Vertical (SPV)’. Two groups of healthy participants with an average age of 25.4 years and 64.5 years respectively, each consisting of 28 healthy participants, sat (blindfolded) on a tilting chair. The subjects’ feeling of being upright was tested under three different conditions of GVS: right-sided anodal stimulation, left-sided anodal stimulation, and sham stimulation. Our findings revealed that right-sided anodal GVS significantly altered the SPV in both age groups, whereas left-sided anodal GVS did not. The observed effect of GVS on perceived upright body posture was numerically small (up to 0.87° on average) and not due to a loss of sensitivity to the perception of body verticality. The unexpected asymmetry of the behavioral effects of GVS could be related to the known right hemispheric asymmetry of cortical activation in vestibular projection areas, which would need to be further clarified in future studies.

The online version contains supplementary material available at 10.1007/s00221-025-07193-7.