Effect of Visually Induced Motion Sickness from Head-Mounted Display on Cardiac Activity

Assessing Passengers' Motion Sickness Levels Based on Cerebral Blood Oxygen Signals and Simulation of Actual Ride Sensation

(1) Background: After motion sickness occurs in the ride process, this can easily cause passengers to have a poor mental state, cold sweats, nausea, and even vomiting symptoms. This study proposes to establish an association model between motion sickness level (MSL) and cerebral blood oxygen signals during a ride. (2) Methods: A riding simulation platform and the functional near-infrared spectroscopy (fNIRS) technology are utilized to monitor the cerebral blood oxygen signals of subjects in a riding simulation experiment. The subjects' scores on the Fast Motion sickness Scale (FMS) are determined every minute during the experiment as the dependent variable to manifest the change in MSL. The Bayesian ridge regression (BRR) algorithm is applied to construct an assessment model of MSL during riding. The score of the Graybiel scale is adopted to preliminarily verify the effectiveness of the MSL evaluation model. Finally, a real vehicle test is developed, and two driving modes are selected in random road conditions to carry out a control test. (3) Results: The predicted MSL in the comfortable mode is significantly less than the MSL value in the normal mode, which is in line with expectations. (4) Conclusions: Changes in cerebral blood oxygen signals have a huge correlation with MSL. The MSL evaluation model proposed in this study has a guiding significance for the early warning and prevention of motion sickness.

Both whole-body rotation and visual flow induce cardiovascular autonomic response in human, but visual response is overridden by vestibular stimulation

While the influence of the vestibular and extra-vestibular gravity signals on the cardiovascular system has been demonstrated, there is little evidence that visual stimuli can trigger cardiovascular responses. Furthermore, there is no evidence of interaction between visual and vestibular signals in autonomic control, as would be expected since they are highly integrated. The present study explored the cardiovascular responses to vestibular and visual stimuli in normal subjects. We hypothesized that the visual stimuli would modify the cardiovascular response to vestibular stimulation, especially when the latter is ambiguous with respect to gravity. Off-Vertical-Axis-Rotation (OVAR) was used to stimulate vestibular and extra-vestibular receptors of gravity in 36 healthy young adults while virtual reality was used for visual stimulation. Arterial pressure (AP), respiratory rate and ECG were measured. The analysis accounted for the respiratory modulation of AP and heart rate (HR). Vestibular stimulation by OVAR was shown to modulate both mean arterial pressure (MAP) and HR, while the visual stimulation was significantly affecting HR modulation, but not MAP. Moreover, the specific visual effect was present only when the subjects were not in rotation. Therefore, visual stimulation is able to modulate the heart rate, but is overridden by vestibular stimulation due to real movement.