Optokinetic stimulation modulates vestibular contribution to postural control

Postural control is a complex ability that requires multisensory integration. For example, some studies demonstrated that vision modulates vestibular contribution but the exact mechanism responsible for this interaction remains poorly understood. Visual-vestibular interactions play a central role in virtual reality-based vestibular rehabilitation and are thought to contribute to conditions such as persistent postural-perceptual dizziness. Consequently, elucidating the mechanisms underlying these interactions is essential. This study aims to investigate the influence of visual perturbation on the vestibular contribution during postural control. A total of 22 healthy young participants were recruited and divided into two groups: Opto (with optokinetic stimulation) and No Opto (without optokinetic stimulation). Participants were submitted to static postural tasks under different conditions where vestibular contribution was assessed using stochastic vestibular stimulation (SVS). No measurable modulation in vestibular contribution was found in participants without optokinetic stimulation (No Opto). Interestingly, the results demonstrated a transient increase in vestibular contribution during the first exposure to optokinetic stimulation (Opto). However, this effect was rapidly inhibited in such way that the vestibular contribution returned to baseline following repeated exposure, suggesting a rapid modulation of the visual input. The results are discussed in relation to sensory reweighting and reference-motion frame models. KEY POINTS: This study aims to investigate the influence of visual perturbation on the vestibular contribution during postural control. The optokinetic stimulation (Opto) group exhibited a marked increase in postural sway and vestibular gain during the first optokinetic exposure, an effect absent in a group without optokinetic stimulation (No Opto). Vestibular-postural coupling remained stable across all stochastic vestibular stimulation (SVS)-only conditions and in the No Opto group, indicating that SVS alone did not induce measurable adaptation. The transient gain increase followed by rapid normalization supports the reference-frame motion model and not classical sensory reweighting. Optokinetic-induced changes were transient, with both gain and postural behaviour returning toward baseline by the fourth exposure, demonstrating rapid visual-vestibular adaptation.