Development of a Virtual Floor Maze Test - Effects of Distal Visual Cues and Correlations With Executive Function in Healthy Adults.

Virtual reality (VR) is a useful tool to assess and improve spatial navigation, a complex skill and relevant marker for progression of dementia. A fully-immersive VR system that allows the user to physically navigate in the space can provide an ecologically valid environment for early detection and remediation of cognitive and navigational deficits. The aim of this study was to develop a virtual version of the floor maze test (VR-FMT), a navigational test that requires navigating through an unfamiliar two-dimensional floor maze. With the VR-FMT, mazes of desired complexity and walls of preferred height can be built to challenge navigational ability and mask visual clues. Fifty-five healthy adults completed the FMT in three different conditions: real environment (RE), virtual environment with no walls (VE-NW), and virtual environment with walls (VE-W). In addition, they completed two neuropsychological tests, the Trail Making Test and Digit Symbol Substitution Test. Results showed that the time to complete the maze in the VE was significantly higher than in the RE. The introduction of walls increased the number of errors, the completion time, and the length of the path. Only time to exit in the VE-W correlated with results of the cognitive tests. Participants were further subdivided on the basis of their time to exit the maze in the RE, VE-NW, and VE-W (low navigational time - LNT, and high navigational time - HNT). Only when analyzing the time to exit the maze in the VE-W, the LNT group outperformed the HNT group in all cognitive tests.

Gait adaptations during overground walking and multidirectional oscillations of the visual field in a virtual reality headset.

BACKGROUND: Virtual reality (VR) has been used to study locomotor adaptability during balance-demanding tasks by exploring how humans react and adapt to the virtual environment (VE) and discordant sensorimotor stimulations. Previous research primarily focused on treadmill walking and little is known regarding the propensity for gait adaptations during overground walking and over time. RESEARCH QUESTION: To what extent healthy young adults modify and adapt gait during overground walking in a VE and with continuous multidirectional perturbations of the visual field while wearing a VR headset? METHODS: Twelve healthy young adults walked for 6 min on an instrumented walkway in four different conditions: RE, VE, and VE with antero-posterior (AP) and medio-lateral (ML) pseudo-random oscillations of the visual field. For each condition, stride length (SL), stride width (SW), stride time (ST) and their variability (SLV, SWV, and STV) were calculated using one-minute walking intervals. A 2-way repeated-measures ANOVA was performed to determine the main and interaction effects of the walking conditions and time. RESULTS: Participants took shorter SL and showed higher SWV while walking in the VE. Perturbations of the visual field resulted in reduced SL, larger SW, and higher stride variability (i.e., SLV, SWV, and STV). The response was anisotropic, such that effects were more pronounced during the ML compared to AP perturbations. Over time, participants adapted to the VE and the visual perturbations by increasing SL and reducing SW, SLV, STV, and ST (only during VE and ML conditions). SWV did not adapt over time. SIGNIFICANCE: The paper provided first evidence for visuomotor adaptations during unperturbed overground walking and during visual perturbations while wearing a VR headset. It represents an initial investigation that may help the development of new VR methods for early detection and remediation of gait deficits in more ecological conditions.