Effects of head-down bed rest and artificial gravity on spatial orientation

Area of Science:

• Space Medicine
• Human Physiology
• Neuroscience

Background:

• Head-down bed rest simulates microgravity effects on human physiology.
• Spatial orientation relies on integrating sensory information, including visual and vestibular inputs.
• Artificial gravity is explored as a countermeasure for spaceflight-induced physiological deconditioning.

Purpose of the Study:

• To investigate the effects of artificial gravity (Gz centrifugation) during head-down bed rest on spatial orientation.
• To assess changes in ocular counter-rolling and subjective visual vertical.
• To determine if artificial gravity mitigates or exacerbates bed rest-induced spatial disorientation.

Main Methods:

• 15 healthy subjects underwent 21 days of 6° head-down bed rest.
• 8 subjects received daily 1-hour Gz centrifugation (2.5 g at feet, 1.0 g at heart).
• 7 subjects served as controls; ocular counter-rolling and subjective visual vertical were measured during 90° whole body roll tilt.

Main Results:

• Ocular counter-rolling remained unaffected by bed rest or artificial gravity treatment.
• Subjective visual vertical performance was unchanged in controls.
• The artificial gravity group showed significantly increased subjective visual vertical errors for 48 hours post-bed rest.

Conclusions:

• Artificial gravity via Gz centrifugation did not affect ocular counter-rolling.
• Intermittent linear acceleration may alter spatial orientation perception, biasing the subjective visual vertical.
• Artificial gravity may increase the weighting of the idiotropic vector, impacting spatial awareness during roll tilt.