Stroboscopic Vision-induced Sensory Re-weighting During Dynamic Postural Control

Abstract

Three main sensory systems (somatosensory, visual, and vestibular) contribute to human postural control. These three sensory systems can compensate for each other if one of them lose their orientation information. Adjusting sensory input is referred to as sensory re-weighting. However, due to experimental limits, little is known how disrupted vision affects sensory re-weighting during dynamic postural control. PURPOSE: Therefore, this study examined the effect of impaired visual sensory input on dynamic postural control through the use of stroboscopic glasses. METHODS: Subjects were 24 physically active adults (male: 12, female: 12, height: 172.1 ± 7.8cm, weight: 67.5 ± 10.4kg) recruited from a university population, aged 18-35 years. Each subject performed the star excursion balance test (SEBT), which includes 3 trials comprised of 3 directions (anterior, posteromedial: PM, and posterolateral: PL) on each visual condition (eyes open: EO, Low Strobe frequency Vision: LSV, High Strobe frequency Vision: HSV) Each trial and visual condition was run on both firm and foam surface. Reach distance was analyzed by 2 (surface conditions) × 3 (vision conditions) ANOVAs. RESULTS: In surface condition main effects, subjects performed significantly (p<.05) shorter reach distances (anterior, PM, and PL). In vision condition main effects, subjects with EO performed significantly lower reach distances in the PM direction than HSV and LSV (p<.05, both), and subjects demonstrated shorter reach distance with EO than with LSV in PL direction (p<.05). Only with HSV, subjects performed shorter reach distance on the foam surface than the firm surface (p<.05). CONCLUSIONS: People with impaired visual sensory (strobe vision) input and/or unstable surface tend to have decreased dynamic postural control when tasked to move in a medial and lateral direction. People also demonstrated higher reliance on visual information when the somatosensory function is disturbed. The stroboscopic glasses may be used to identify the reliance of visual information in people who have an altered or reduced somatosensory system.