Visual Occlusion Decreases Motion Sickness in a Flight Simulator

Motion Sickness and visual impairment

Motion sickness (MS) is caused by exposure to unfamiliar movements. The theory is that MS is due to a conflict between information perceived by the vestibular, visual, and somatosensory systems. This study examines the role of vision in MS by comparing MS susceptibility among individuals with varying degrees of visual impairments to sighted individuals. We hypothesized that subjects with no perception of light would be less susceptible to MS than less impaired subjects, who would themselves be less susceptible than sighted subjects. To address these, the Motion Sickness Susceptibility Questionnaire (MSSQ1) was administered to 340 subjects (170 visually impaired paired with 170 sighted subjects) to assess their susceptibility to various modes of transport under real conditions. Visually impaired subjects were divided into subgroups according to the presence (partially sighted) or absence (totally blind) of light perception, as well as the period of onset of impairment (congenital or acquired). Totally blind individuals are significantly less susceptible to MS than partially sighted (p = 0.001), and sighted (p < 0.001) subjects, with no difference between partially sighted and sighted subjects (p = 0.526). Additionally, acquired totally blind subjects are less susceptible to MS than congenitally blind subjects (p = 0.038). Thus, despite a lower susceptibility totally blind subjects may still be susceptible to MS. The absence of vision reduces MS susceptibility but does not completely prevent it. This suggests that vision is more a mediator, than an essential condition for MS appearance.

EEG-based evaluation of motion sickness and reducing sensory conflict in a simulated autonomous driving environment

Autonomous driving offers significant potential for changes in the automotive industry. However, sensory conflict during autonomous driving can lead to motion sickness. Quantitative evaluation and effective preventions to predict and reduce motion sickness are needed. The goal of this study is to verify the objective indicator of motion sickness level based on encephalography (EEG) that we proposed before and investigate the influence of attenuating sensory conflict on motion sickness. A 6-degree of freedom (DOF) driving simulator platform was used to provide an autonomous driving environment to the subjects, and the subjective motion sickness level (MSL), as well as the EEG signals of 15 healthy subjects, were collected simultaneously during 3 conditions, i) autonomous driving, ii) autonomous driving with eyes blindfolded and iii) active driving. The MSLs were reported by the subjects every two minutes, providing a reference to the recorded EEG signals. The EEG signals were analyzed and compared among different conditions. Average MSLs were higher in autonomous driving than in autonomous driving with eyes blindfolded and active driving, together with the increase of the mean EEG frequency of theta band in the central, parietal and occipital areas (FC5, Cz, CP5, P3, and POz). These findings validated that EEG mean frequency of theta band could be an indicator of motion sickness, besides an attenuated visual input or active control of the vehicle can effectively reduce the generation of motion sickness.

Motion sickness: an overview

Background

Motion sickness is a common phenomenon that affects almost everybody at some point in their lifetime. Clinicians should be familiar with the proper management of this condition.

Objective

To provide an update on the current understanding of the pathophysiology and management of motion sickness.

Methods

A PubMed search was performed with Clinical Queries using the key term ‘motion sickness.’ The search strategy included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews. The search was restricted to English literature. The information retrieved from the earlier search was used in the compilation of the present article.

Results

Motion sickness is typically triggered by low-frequency vertical, lateral, angular, rotary motion, or virtual stimulator motion, to which an individual has not adapted. Sine qua non for developing motion sickness is when the brain receives conflicting information from different sensors about real body movements or virtual environment. The principal sensors are the eyes, the vestibular apparatus, and proprioceptive receptors. The conflicting information is judged in relation to a pattern of expected associations formed under normal or experienced conditions stored in the brain. Motion sickness typically presents with malaise, anorexia, nausea, yawning, sighing, increased salivation, burping, headache, blurred vision, non-vertiginous dizziness, drowsiness, spatial disorientation, difficulty concentrating, and sometimes vomiting. Simple behavioral and environmental modifications can be effective in the prevention of motion sickness. Medications that are effective in the prophylaxis and/or treatment of motion sickness include anticholinergics, antihistamines, and sympathomimetics.

Conclusion

In most cases, motion sickness can be prevented by behavioral and environmental modifications (avoidance, habituation, and minimization of motion stimuli). Pharmacotherapy should be considered in the prevention and/or treatment of more severe motion sickness and for patients who do not respond to conservative measures. Medications are most effective when combined with behavioral and environmental modifications. Drugs that are effective in the prophylaxis and/or treatment of motion sickness include anticholinergic agents and antihistamines.