The rubber hand illusion in microgravity and water immersion

Area of Science:

• Neuroscience
• Human Physiology
• Gravitational Biology

Background:

• Human physiological systems, including sensory integration, are adapted to Earth's terrestrial gravity.
• Altered gravitational conditions, such as those experienced during spaceflight or parabolic flights, can challenge these adaptations.
• The sense of body ownership (SBO) relies on the integration of visual, proprioceptive, and vestibular information.

Purpose of the Study:

• To investigate how altered gravitational conditions influence the sense of body ownership (SBO).
• To examine the impact of unconventional gravity on susceptibility to the rubber hand illusion (RHI).
• To determine how sensory input weighting (visual, proprioceptive, vestibular) changes under altered gravity.

Main Methods:

• The study employed the rubber hand illusion (RHI) paradigm to assess SBO.
• Experiments were conducted during two conditions of altered gravity: water immersion and parabolic flights.
• Susceptibility to the RHI was measured under these unconventional gravitational conditions.

Main Results:

• Unconventional gravity conditions significantly remodulate the integration of sensory inputs.
• There was a notable shift in the relative weighting of visual, proprioceptive, and vestibular signals.
• Visual input was favored, leading to an increased susceptibility to the rubber hand illusion (RHI).

Conclusions:

• Altered gravity conditions can modulate the sense of body ownership (SBO).
• The brain adapts by re-weighting sensory inputs, prioritizing vision under non-terrestrial gravity.
• This sensory re-weighting increases susceptibility to illusions like the RHI, impacting body perception.