Decreased susceptibility to motion sickness during exposure to visual inversion in microgravity

Area of Science:

• Neuroscience
• Space Medicine
• Human Physiology

Background:

• Head and body movements in microgravity often induce motion sickness.
• Unusual vestibular (semicircular canal and otolith) activity occurs during head movements in microgravity due to otolith unloading.
• Visual inversion on Earth causes motion sickness because the vestibulo-ocular reflex becomes anti-compensatory.

Purpose of the Study:

• To investigate the effect of a microgravity (0G) background on susceptibility to motion sickness induced by visual inversion.
• To explore the role of otolith function in modulating motion sickness during visual inversion in different gravitational conditions.

Main Methods:

• Participants were exposed to visual inversion stimuli under both 0G and 1G conditions.
• Susceptibility to motion sickness was assessed during these exposures.
• Vestibular (otolith) function was evaluated in relation to motion sickness symptoms.

Main Results:

• Susceptibility to motion sickness during visual inversion was significantly decreased in 0G compared to 1G.
• This reduction in susceptibility in 0G appears to be related to altered otolith function.

Conclusions:

• Altered otolith function in microgravity may play a role in reducing susceptibility to visually induced motion sickness.
• Findings provide insights into the etiology of space motion sickness and the sensory conflict theory.