Eye-Head Coordination in 31 Space Shuttle Astronauts during Visual Target Acquisition.

Area of Science:

• Space Medicine
• Human Physiology
• Neuroscience

Background:

• NASA's Space Shuttle program investigated astronaut health and performance during missions up to 17 days.
• Understanding the physiological effects of spaceflight on sensorimotor functions is crucial for astronaut safety.

Purpose of the Study:

• To evaluate the impact of spaceflight duration on astronaut gaze control and sensorimotor performance.
• To quantify changes in eye and head movements post-flight.

Main Methods:

• Thirty-one astronauts from 17 Space Shuttle missions were assessed before and after flight.
• Electro-oculography (EOG) measured eye movements, while a triaxial rate sensor system measured head movements.
• Participants performed rapid head and eye movements to visual targets at varying eccentricities.

Main Results:

• Immediately post-flight, astronauts showed a 7-10% (30-34 ms) increase in gaze latency compared to preflight baseline.
• This delay was attributed to reduced velocity and amplitude of both eye saccades and head movements.
• Sensorimotor performance recovered to baseline levels within 48 hours post-landing.

Conclusions:

• Spaceflight temporarily impairs gaze control, affecting the speed and accuracy of visual target acquisition.
• The observed deficits in sensorimotor function are transient and do not appear to be dose-dependent on flight duration up to 17 days.
• These findings highlight the need for post-flight rehabilitation and monitoring of sensorimotor systems in astronauts.