Visual and vestibular reweighting after cyber- and space-sickness

Area of Science:

• Neuroscience
• Human Physiology
• Sensory Integration

Background:

• Sensory conflicts are primary drivers of motion sickness (MS).
• The underlying sensory integration processes in MS are not well understood.
• Understanding sensory reweighting is crucial for mitigating MS.

Purpose of the Study:

• To investigate sensory reweighting following different sensory conflict paradigms.
• To assess how the brain adjusts reliance on visual and vestibular inputs.
• To explore the relationship between sensory sensitivity and MS susceptibility.

Main Methods:

• Assessed visual and vestibular reflexes before and after sensory conflict exposure.
• Used virtual reality (VR) for visuo-vestibular conflict (vection).
• Utilized parabolic flight for vestibular conflict (gravitational changes).
• Measured semi-circular canal integration via vestibulo-ocular reflex (VOR) suppression.
• Assessed visual input weight using optokinetic nystagmus (OKN).

Main Results:

• VR exposure reduced VOR response by 12%, indicating decreased vestibular reliance.
• Parabolic flight diminished OKN performance by 13%, indicating reduced visual input reliance.
• Sensory modality failing to detect motion was assigned reduced contribution.
• Visual sensitivity correlated with increased cybersickness susceptibility.
• Vestibular sensitivity correlated with MS severity during parabolic flight.

Conclusions:

• The brain down-weights sensory input perceived as less reliable during conflict.
• Sensory reweighting is a key mechanism in motion sickness.
• Individual sensitivity in the most stimulated sensory modality may predict MS susceptibility.