Cyclovergence evoked by up-down acceleration along longitudinal axis in humans.
We present results of a study of torsional eye movements evoked by earth-vertical accelerations along the subject's longitudinal axis. The earth-vertical stimulus leads to a gravito-inertial acceleration vector that changes magnitude but not direction. It can therefore be viewed as a dynamic change of the gravity level. Up-down oscillations induced relatively symmetric cyclovergence (0.6-2.2 degrees peak-to-peak). Eyes intorted/extorted for higher/lower effective gravity. The phase of this modulation was small relative to chair acceleration. We contrast this behaviour to the dynamics of cycloversion in response to interaural acceleration, which shows a considerably larger phase lag. This strikingly different dynamics suggest a different processing of otolith signals during interaural and longitudinal stimulation.
Olasagasti
I
I
Department of Neurology, Zurich University Hospital, Zurich, Switzerland. miren.olasagasti@usz.ch
Bockisch
C J
CJ
Zee
D S
DS
Straumann
D
D
D000054:Acceleration; D003290:Convergence, Ocular / Q000502:physiology*; D005133:Eye Movements / Q000502:physiology*; D006112:Gravitation; D019416:Head Movements / Q000502:physiology; D006801:Humans; D009039:Motion Perception / Q000502:physiology