Assessment of vestibulo-ocular reflex and its adaptation during stop-and-go car rides in motion sickness susceptible passengers

Abstract

Motion sickness is a physiological condition that negatively impacts a person's comfort and will be an emerging condition in autonomous vehicles without proper countermeasures. The vestibular system plays a key role in the origin of motion sickness. Understanding the susceptibility and (mal) adaptive mechanisms of the highly integrated vestibular system is a prerequisite for the development of countermeasures. We hypothesize a differential association between motion sickness and vestibular function in healthy individuals with and without susceptibility for motion sickness. We quantified vestibular function by measuring the high-frequency vestibulo-ocular reflex (VOR) using video head impulse testing (vHIT) in 17 healthy volunteers before and after a 11 min motion sickness-inducing naturalistic stop-and-go car ride on a test track (Dekra Test Oval, Klettwitz, Germany). The cohort was classified as motion sickness susceptible (n = 11) and non-susceptible (n = 6). Six (out of 11) susceptible participants developed nausea symptoms, while a total of nine participants were free of these symptoms. The VOR gain (1) did not differ significantly between participant groups with (n = 8) and without motion sickness symptoms (n = 9), (2) did not differ significantly in the factor time before and after the car ride, and showed no interaction between symptom groups and time, as indicated by a repeated measures ANOVA (F(1,15) = 2.19, p = 0.16. Bayesian inference confirmed that there was "anecdotal evidence" for equality of gain rather than difference across groups and time (BF₁₀ < 0.77). Our results suggest that individual differences in VOR measures or adaptation to motion sickness provocative stimuli during naturalistic stop-and-go driving cannot predict motion sickness susceptibility or the likelihood of developing motion sickness.

Keywords: Adaptation; Motion sickness; Stop-and-go car ride; Vestibulo-ocular reflex; Video head impulse test.

Fig. 1

Experimental procedure. Prior to the recording sessions, all participants were classified to either a "susceptible" or "non-susceptible" to motion sickness. All participants underwent a video head impulse test (vHIT) before and after the stop-and-go car ride

Fig. 2

Seventeen participants were divided into four subgroups based on self-reported susceptibility and nausea outcome during motion exposure. Participants were divided into two groups, "asymptomatic" and "symptomatic", based on the occurrence of nausea symptoms (nausea score greater than zero) during the car ride

Fig. 3

Boxplots showing groupwise VOR gain values before (pre) and after (post) the car ride for asymptomatic participants (A) compared to symptomatic participants (B). Dots represent individual VOR gain values connected by a gray line for each participant. Black triangles represent mean VOR gain values for groups and timepoints. C Interactions between pre-post measures and symptomatic groups, i.e., symptomatic (gray) and asymptomatic (black)