Motion sickness in the squirrel monkey

Area of Science:

• Neuroscience
• Primatology
• Aerospace Medicine

Background:

• Squirrel monkeys (order Primates) serve as nonhuman primate models for motion and space sickness research.
• Understanding susceptibility, prevention, and neural mechanisms of space sickness is crucial for human spaceflight.

Purpose of the Study:

• To investigate factors influencing motion and space sickness susceptibility in squirrel monkeys.
• Specific aims included examining effects of motion stimuli, phenotype, sex, visual cues, testing time, and repeated exposures on emetic responses.

Main Methods:

• Squirrel monkeys were exposed to combined vertical rotation and horizontal acceleration.
• Emetic incidence, frequency, and latency were recorded.
• Factors analyzed included phenotype (Bolivian vs. Colombian), sex, presence of visual cues, time of day, and repeated testing.

Main Results:

• The highest emetic incidence (89%), frequency (2.0/60 min), and latency (19 min) occurred at 25 rpm and 0.5 Hz linear acceleration.
• Susceptibility was significantly higher in Bolivian vs. Colombian phenotypes, with visual cues, and in males.
• No significant differences were found based on time of day or with successive test exposures.

Conclusions:

• Squirrel monkey emetic responses to motion stimuli closely resemble those in humans.
• The squirrel monkey is a highly suitable primate model for motion and space sickness research.