Postural instability in an immersive Virtual Reality adapts with repetition and includes directional and gender specific effects

Per-Anders Fransson,Mitesh Patel,Fredrik Tjernström,Måns Magnusson,Hanna Jensen,Eva Ekvall Hansson,Michèle Lundberg

doi:10.1038/s41598-019-39104-6

Per-Anders Fransson, Mitesh Patel + Show 5 more

Open Access

https://doi.org/10.1038/s41598-019-39104-6

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Journal: Scientific Reports	Publication Date: Feb 28, 2019
Citations: 32	License type: open-access

Affiliation: Lund University, Imperial College London

Abstract

The ability to handle sensory conflicts and use the most appropriate sensory information is vital for successful recovery of human postural control after injury. The objective was to determine if virtual reality (VR) could provide a vehicle for sensory training, and determine the temporal and spatial nature of such adaptive changes. Twenty healthy subjects participated in the study (10 females). The subjects watched a 90-second VR simulation of railroad (rollercoaster) motion in mountainous terrain during five repeated simulations, while standing on a force platform that recorded their stability. The immediate response to watching the VR movie was an increased level of postural instability. Repeatedly watching the same VR movie significantly reduced both the anteroposterior (62%, p < 0.001) and lateral (47%, p = 0.001) energy used. However, females adapted more slowly to the VR stimuli as reflected by higher use of total (p = 0.007), low frequency (p = 0.027) and high frequency (p = 0.026) energy. Healthy subjects can significantly adapt to a multidirectional, provocative, visual environment after 4–5 repeated sessions of VR. Consequently, VR technology might be an effective tool for rehabilitation involving visual desensitisation. However, some females may require more training sessions to achieve effects with VR.

Highlights

When we move and interact with the environment, the central nervous system (CNS) must detect and counter egocentric body movements produced by sensory information from physical or visual motion
Twenty healthy subjects participated in the study (10 females)
We demonstrated that watching a virtual reality (VR) movie that induced provocative visual motion caused strong balance perturbations during the first session resulting in an energy usage towards the support surface by about 26 to 47 times larger high frequency energy than the levels recorded during the quiet stance control test with eyes open

Summary

Introduction

When we move and interact with the environment, the central nervous system (CNS) must detect and counter egocentric body movements produced by sensory information from physical or visual motion. VR can be set up to be strongly immersive, in that the environment appears real and three-dimensional, to induce reliable ego-motion. This is useful experimentally as VR can induce motor responses to an unexpected veridical virtual input. Adaptive postural skills to sensory conflicts are reduced in individuals susceptible to motion sickness, seasickness. As visual motion is a provocative and reliable stimulus for motion sickness, we wanted to test whether low and high frequency postural responses adapt during quiet stance in a provocative VR environment. We explored gender effects, as a higher incidence of motion sickness and postural sway has been reported in females over males in VR experiments[9]

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