Ocular counter-roll is less affected in experienced versus novice space crew after long-duration spaceflight

Abstract

Otoliths are the primary gravity sensors of the vestibular system and are responsible for the ocular counter-roll (OCR). This compensatory eye torsion ensures gaze stabilization and is sensitive to a head roll with respect to gravity and the Gravito-Inertial Acceleration vector during, e.g., centrifugation. To measure the effect of prolonged spaceflight on the otoliths, we quantified the OCR induced by off-axis centrifugation in a group of 27 cosmonauts in an upright position before and after their 6-month space mission to the International Space Station. We observed a significant decrease in OCR early postflight, larger for first-time compared to experienced flyers. We also found a significantly larger torsion for the inner eye, the eye closest to the rotation axis. Our results suggest that experienced cosmonauts have acquired the ability to adapt faster after G-transitions. These data provide a scientific basis for sending experienced cosmonauts on challenging missions that include multiple g-level transitions.

Cognitive and balance functions of astronauts after spaceflight are comparable to those of individuals with bilateral vestibulopathy

“…Another limitation is that the BVP subjects did not experience nausea, but the astronauts showed motion sickness symptoms, especially on R + 0 ( 27 ). However, previous studies have shown that the vertical and roll VOR gain during head oscillations ( 28 ) and the ocular counter-rolling during head tilt ( 29 ) or centrifugation ( 5 , 30 ) were decreased in astronauts immediately after landing. Although there is no report of VEMP after spaceflight in astronauts, cVEMP amplitude was found to be greater in microgravity during parabolic flight than in normal gravity ( 31 ).…”

Back to the future—revisiting Skylab data on ocular counter-rolling and motion sickness

“…Evidence indicates that OCR during static body tilt or lateral centrifugation decreases after spaceflight, particularly after longduration space missions (Hallgren et al, 2016;Reschke et al, 2018;Schoenmaeker et al, 2022). Six of the Skylab astronauts' preflight OCR amplitudes were lower than of the normal population.…”

Neuroplasticity in F16 fighter jet pilots

“…The brain will then adapt to the intersensory conflicts by altering the processing of sensory input ( Kornilova and Kozlovskaia, 2003 ). Yet, these phenomena appear to decrease throughout time with training, after several days in microgravity, and by repeated exposure to microgravity, providing evidence for vestibular adaptations ( Reschke et al, 1998 ; Schoenmaekers et al, 2022 ). Several hypotheses have been put forward to explain the origin of space motion sickness.…”