[The Effects of Optokinetic Stimulation on Visual-Manual Tracking under Support-Proprioceptive Deprivation.]

Area of Science:

• Neuroscience
• Human Physiology
• Sensory Perception

Background:

• Dry immersion simulates microgravity, inducing sensory deprivation and afferent deficit.
• Visual-manual tracking (VMT) performance is crucial for tasks requiring hand-eye coordination.
• Proprioceptive afferentation reduction impacts motor control and spatial orientation.

Purpose of the Study:

• To investigate the effects of retinal optokinetic stimulation (ROKS) on VMT.
• To assess VMT performance under conditions of reduced proprioception and sensory deprivation.
• To evaluate the potential of ROKS to mitigate sensory-induced performance decrements.

Main Methods:

• 18 healthy subjects underwent 5-7 days of horizontal dry immersion.
• Visual-manual tracking (VMT) was assessed using saccadic and smooth pursuit tasks.
• Eye movements (electrooculography) and hand movements (joystick) were recorded with and without ROKS via virtual reality.

Main Results:

• Without ROKS, VMT performance (efficiency, gain) significantly decreased during and after immersion, particularly for visual tracking.
• With ROKS, VMT parameters remained stable pre-immersion and improved during/post-immersion compared to no-ROKS conditions.
• ROKS demonstrated the greatest impact on visual tracking, while vestibular function showed altered responses post-immersion.

Conclusions:

• Dry immersion induces sensory deprivation and afferent deficit, impairing VMT.
• Retinal optokinetic stimulation (ROKS) effectively corrects VMT deficits caused by sensory deprivation.
• ROKS offers a promising countermeasure for maintaining motor control in altered sensory environments.