Vision Affects Gait Speed but not Patterns of Muscle Activation During Inclined Walking-A Virtual Reality Study

Amit Benady; Sean Zadik; Oran Ben-Gal; Desiderio Cano Porras; Atalia Wenkert; Sharon Gilaie-Dotan; Meir Plotnik

doi:10.3389/fbioe.2021.632594

Vision Affects Gait Speed but not Patterns of Muscle Activation During Inclined Walking-A Virtual Reality Study

Front Bioeng Biotechnol. 2021 Apr 9:9:632594. doi: 10.3389/fbioe.2021.632594. eCollection 2021.

Authors

Amit Benady^{1

2

3}, Sean Zadik^{1

2}, Oran Ben-Gal¹, Desiderio Cano Porras^{1

4}, Atalia Wenkert¹, Sharon Gilaie-Dotan^{3

5

6}, Meir Plotnik^{1

7

8}

Affiliations

¹ Center of Advanced Technologies in Rehabilitation, Sheba Medical Center, Ramat Gan, Israel.
² St George's University of London Medical School, Sheba Medical Center, Ramat Gan, Israel.
³ School of Optometry and Vision Science, Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel.
⁴ Brightlands Institute for Smart Society (BISS), Maastricht University, Maastricht, Netherlands.
⁵ UCL Institute of Cognitive Neuroscience, London, United Kingdom.
⁶ The Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat Gan, Israel.
⁷ Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
⁸ Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.

Abstract

While walking, our locomotion is affected by and adapts to the environment based on vision- and body-based (vestibular and proprioception) cues. When transitioning to downhill walking, we modulate gait by braking to avoid uncontrolled acceleration, and when transitioning to uphill walking, we exert effort to avoid deceleration. In this study, we aimed to measure the influence of visual inputs on this behavior and on muscle activation. Specifically, we aimed to explore whether the gait speed modulations triggered by mere visual cues after transitioning to virtually inclined surface walking are accompanied by changes in muscle activation patterns typical to those triggered by veridical (gravitational) surface inclination transitions. We used an immersive virtual reality system equipped with a self-paced treadmill and projected visual scenes that allowed us to modulate physical-visual inclination congruence parametrically. Gait speed and leg muscle electromyography were measured in 12 healthy young adults. In addition, the magnitude of subjective visual verticality misperception (SVV) was measured by the rod and frame test. During virtual (non-veridical) inclination transitions, vision modulated gait speed by (i) slowing down to counteract the excepted gravitational "boost" in virtual downhill inclinations and (ii) speeding up to counteract the expected gravity resistance in virtual uphill inclinations. These gait speed modulations were reflected in muscle activation intensity changes and associated with SVV misperception. However, temporal patterns of muscle activation were not affected by virtual (visual) inclination transitions. Our results delineate the contribution of vision to locomotion and may lead to enhanced rehabilitation strategies for neurological disorders affecting movement.

Keywords: electromyography; inclined surfaces; locomotion; rod-and-frame; visual dependency; visuomotor integration.