Inducing Compensatory Changes in Gait Similar to External Perturbations Using an Immersive Head Mounted Display

Understanding the sensorimotor control mechanisms that mediate gait compensation during environmental perturbation is a crucial step in developing tailored rehabilitative therapies to restore ambulation in patient populations. Current methods to evaluate the effects of environmental perturbations involve costly systems that physically perturb patients to elicit a compensatory response. Studies have shown that visual feedback alone can elicit dramatic changes in gait; however, the impact of fully immersive visual feedback is not well studied. Here we examined whether a low cost immersive virtual reality (VR) system can elicit perturbation responses similar to a physical disruption. We examined the responses of 11 subjects as they walked through a VR environment consisting of a bridge spanning a lake. While subjects walked on a treadmill mounted to a 6 degree-of-freedom motion base, pseudorandom roll perturbations (3, 6, 11 deg.) were applied visually to the bridge with (VP trials) and without (V trials) the corresponding physical displacement of the motion base. Significant differences were found between normal (unperturbed) walking and normal walking in the VR environment (p<.05) for average step length, width, and Margin of Stability (MoS). Significant differences were also observed between unperturbed and perturbed walking in the VR environment (p<0.05 for VP and V trials). While the subjects' responses to visual perturbations were generally lower than to combined visual and physical perturbations, the differences were not statistically significant (p>.05). The results demonstrate that visual perturbations provided in an immersive virtual environment can induce compensatory changes in gait during treadmill walking that are consistent with a physical perturbation. The application of environmental perturbations in VR systems could provide a cost-effective approach for gait rehabilitation in patient populations.