gravitational input, supposedly related to a re-weighting of the internal model of gravity, or lack
thereof, as an adaptation to microgravity.
These results suggest a separation between otolith-driven eye movement and orientation
perception during passive vestibular stimulation by inertial motion after spaceflight, and
support the conclusion that otolith-driven compensatory eye movement and orientation
perception are controlled by different neural mechanisms. OCR is primarily a direct response of
otolith activation by low-frequency linear acceleration along the axis between the ears,
whereas perception of tilt is primarily governed by the integration of otolith inputs, as well as
bodily sensations such as position of limbs and pressure on the skin and internal organs.
Apparently, the peripheral vestibular organ showed little or no changes after 10-13 days
spaceflight, thus otolith-driven eye movements appear relatively unaffected by short-term
exposure to microgravity. However, the central processing of orientation relative to gravity is
likely to be affected and suggests why perceptual and oculomotor responses dependent on
central vestibular processing can be greatly disrupted (Clement 2007, 2012).
PUBLICATION(S)
Clement G, Wood SJ. Eye movements and motion perception during off-vertical axis rotation
after spaceflight. Journal of Vestibular Research. January 1, 2013;23(1):13-22. doi: 10.3233/VES-
130471.
Clement G, Denise P, Reschke MF, Wood SJ. Human ocular counter-rolling and roll tilt
perception during off-vertical axis rotation after spaceflight. Journal of Vestibular Research.
2007;17(5-6):209-215.
This investigation is complete and all results are published.