Susceptibility to visually induced motion sickness (VIMSS) can prevent people from enjoying 3D films, VR games, and many other entertainments involving self-motion illusion (vection). The mechanism of VIMSS has not been completely understood. In particular, little is known on how the brains of susceptible and resistant individuals differ in responding to VIMS-provoking stimulations. Furthermore, objective and reliable indicators of VIMSS is lack. This research investigates the mechanism and objective indicators for VIMSS from the electroencephalographs (EEG) during a short exposure to VIMS-provoking stimulations. To verify the reliability of the indicators, the VIMSS of each individual was manipulated by a habituation training and the change in VIMSS was validated with two objective mea...[ Read more ]

Susceptibility to visually induced motion sickness (VIMSS) can prevent people from enjoying 3D films, VR games, and many other entertainments involving self-motion illusion (vection). The mechanism of VIMSS has not been completely understood. In particular, little is known on how the brains of susceptible and resistant individuals differ in responding to VIMS-provoking stimulations. Furthermore, objective and reliable indicators of VIMSS is lack. This research investigates the mechanism and objective indicators for VIMSS from the electroencephalographs (EEG) during a short exposure to VIMS-provoking stimulations. To verify the reliability of the indicators, the VIMSS of each individual was manipulated by a habituation training and the change in VIMSS was validated with two objective measuremens, visual dependency and postural instability. In the current study, rotating random dots around roll and pitch axes were utilized to provoke VIMS and to elicit EEG activities in short exposures. Thirty-four participants were classified into resistant and susceptible groups. To investigate the effect of habituation on VIMSS, participants went through a 7-to-10-day training. Before training, when watching rotating dots in both axes, EEG phase synchronization between the signal from the right parietal region (P4) and signals from central, parietal and occipital regions was significantly higher among the resistant group, while that between signals from two central sites (C3-C4) was significantly higher among the susceptible group. Besides, the synchronization to P4 negatively correlated with VIMS and could be related to neural coordination to relieve VIMS. Positive correlations were found between VIMS and the interhemispheric synchronization (C3-C4), which could indicate a direct response to sensory conflict or VIMS severity. After the training, there was a significant increment in the parietal synchronization (P4-P7) among individuals trained to be resistant from the susceptible group. The interhemispheric synchronization (C3-C4) was also lower after training. For the first time, we have discovered EEG synchronization indictors that associated the influence of habituation with both reductions in sickness and increases in resistance to VIMS. The two opposite EEG indicators suggest that VIMS could be the consequence of two antagonistic neural activities, and habituation training could reduce the VIMS response by affecting both. Furthermore, less visual dependence and a narrower postural sway range along the x-axis (left to right) were found among the susceptible group after training. The changes in behavioral performance could also be evidence of the effect of habituation on visual-vestibular interaction. The newly discovered EEG phase synchronization indicators offer a new method to predict VIMS susceptibility.