Greater functional activation during galvanic vestibular stimulation is associated with improved postural stability: a GVS-fMRI study.

ABSTRACT

PURPOSE: Previous literature has shown that standing stability relies on the vestibular system; however, the neural correlates underlying standing stability remains unclear. This study aimed to investigate the neural correlates of standing stability using functional magnetic resonance imaging (fMRI) following galvanic vestibular stimulation (GVS). MATERIALS AND METHODS: Forty-five healthy right-handed healthy volunteers were included. Postural stability was measured using the modified Clinical Test of Sensory Interaction and Balance (mCTSIB), which measures swaying speed and area on hard and soft surfaces when the volunteer's eyes are open and closed. Functional activation as determined by the blood oxygenation level-dependent (BOLD) response, was measured during GVS using fMRI. We investigated the association between BOLD responses during GVS and postural stability. RESULTS: Relative to rest, participants showed significantly higher BOLD signal during GVS in the parietal operculum, central operculum, and the opercular part of the inferior frontal gyrus. Moreover, functional activation in the central operculum was negatively correlated with standing stability, indexed using swaying speed when volunteers stood on a foam surface with their eyes closed. CONCLUSIONS: Our findings suggest that the neural correlates of standing stability involve greater functional activation in the central operculum.