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Alzheimer's disease (AD) is a growing global crisis. Egocentric spatial orientation deteriorates with age and more significantly with AD. A simple and quick virtual reality (VR) localization and target finding technique is presented as a diagnostic aid to screen mild cognitive impairment (MCI) from AD. Spatial orientation data from 93 individuals (65 AD at a mild stage, 20 MCI, and 8 other dementia types) based on VR localization of a target on a landmark-less cubic 3-story building were analyzed. We hypothesize AD and MCI groups' performances are significantly different. AD and MCI spatial performances were statistically significantly (p < 0.001) different. These results plus the longitudinal tracking of three patients who developed AD over a period of 5 years suggest the proposed spatial tests may be used as a quick and simple clinical diagnostic aid to separate AD at early to mild stages from MCI., (© 2021. International Federation for Medical and Biological Engineering.)

Electrovestibulography (EVestG), a technology purported to measure vestibular activity at the vestibular periphery, was used to compare the vestibular responses to two sensory inputs: (1) back-forward physical tilt (with eyes-open and eyes-closed) and (2) virtual reality replica of the back-forward tilt (eyes-open, physically static). Twenty-seven healthy participants (10 females) were tested. From each of the EVestG recordings, two feature curves: (1) average field potential (FP), and (2) distribution of time intervals between the detected FPs were extracted. For the eyes-closed physical tilt, except for the background segment, the FP response curve was generally wider compared to that evoked during the virtual replica tilt (p < 0.05). Moreover, the eyes-closed physical tilt produced longer time intervals between FP's compared to the virtual stimulus. For this measure, for the background segment, the eyes closed and open physical tilt responses were significantly different (p < 0.05) in both ears (repeated measure experimental design). The results support: (1) both vestibular and visual inputs evoking a measurably different EVestG response, (2) the differences between physical and virtual vestibular responses are dependent on the eyes being either open or closed, and (3) for the stimuli used, the modulation of vestibular afferent activity was measurably smaller for virtual than physical stimulation.

Vection is defined as an illusory self-motion sensation induced in stationary observers that can be experienced in a real/virtual world. Vection, as a result of immersion in virtual reality (VR) environments, can subsequently lead to a sense of inability to maintain postural control and cause cybersickness symptoms. The multisensory integration of visual and vestibular (balance) information plays a vital role in vection. The etiology of vection perception, as well as, the vestibular response change while experiencing vection is poorly understood. This study explores vestibular response change following vection in 20 individuals (10 females, 26.45 ± 4.40 (SD) years). Vection was induced in participants using an immersive VR roller-coaster. The vestibular response was measured simultaneously using a noninvasive method called Electrovestibulography (EVestG). The detected field potentials and the time intervals between the field potentials were extracted from the recorded EVestG signals corresponding to four segments of the VR roller-coaster trajectory namely Stationary, Up movement, Down movement, and slopes and turns (Mix). The results show that the Stationary segment is significantly different (P < 0.05) from other dynamic segments when the average field potential of the right and left ear are subtracted. Furthermore, the Stationary segment shows longer time intervals between field potentials compared to those of the other segments in the right ear. These observations suggest that the combined effect of the visually induced sensation of self-motion together with a concurrent/co-occurring stress/anxiety factor can affect the vestibular activity in an excitatory way. Increased excitatory vestibular activity implies increased feeling of imbalance and more likelihood of experiencing cybersickness by the participants. [ABSTRACT FROM AUTHOR]