Decreased otolith-mediated vestibular response in 25 astronauts induced by long-duration spaceflight

Emma Hallgren, Ludmila Kornilova, Erik Fransen, Dmitrii Glukhikh, Steven T. Moore, Gilles Clément, Angelique Van Ombergen, Hamish MacDougall, Ivan Naumov, Floris L. Wuyts

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58 Scopus citations


The information coming from the vestibular otolith organs is important for the brain when reflexively making appropriate visual and spinal corrections to maintain balance. Symptoms related to failed balance control and navigation are commonly observed in astronauts returning from space. To investigate the effect of microgravity exposure on the otoliths, we studied the otolith-mediated responses elicited by centrifugation in a group of 25 astronauts before and after 6 mo of spaceflight. Ocular counterrolling (OCR) is an otolith-driven reflex that is sensitive to head tilt with regard to gravity and tilts of the gravito-inertial acceleration vector during centrifugation. When comparing pre- and postflight OCR, we found a statistically significant decrease of the OCR response upon return. Nine days after return, the OCR was back at preflight level, indicating a full recovery. Our large study sample allows for more general physiological conclusions about the effect of prolonged microgravity on the otolith system. A deconditioned otolith system is thought to be the cause of several of the negative effects seen in returning astronauts, such as spatial disorientation and orthostatic intolerance. This knowledge should be taken into account for future long-term space missions.

Original languageEnglish
Pages (from-to)3045-3051
Number of pages7
JournalJournal of Neurophysiology
Issue number6
StatePublished - 1 Jun 2016


  • Artificial gravity
  • Centrifugation
  • Ocular counterrolling
  • Otolith function
  • Spaceflight


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