Geometric relations of eye position and velocity vectors during saccades.
Measurements of angular position and velocity vectors of the eye in three human and three monkey subjects showed that: (1) position vectors lie roughly in a single plane, in accordance with Listing's law, between and during saccades; (2) primary position of the eye is often far from the centre of the oculomotor range. (3) saccades have nearly-fixed rotation axes, which tilt out of Listing's plane in a systematic way depending on current eye position. Findings 1 and 3 show that saccadic control signals accurately reflect the properties of three-dimensional rotations, as predicted by a new quaternion model of the saccadic system; models that approximate rotational kinematics using vectorial addition and integration do not predict these findings.
Tweed
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Department of Physiology, University of Western Ontario, London, Canada.
Vilis
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D000328:Adult; D000818:Animals; D001696:Biomechanical Phenomena; D004864:Equipment and Supplies; D005123:Eye / Q000033:anatomy & histology; D005133:Eye Movements / Q000502:physiology*; D005403:Fixation, Ocular; D006801:Humans; D008252:Macaca fascicularis; D008297:Male; D008954:Models, Biological; D012438:Saccades / Q000502:physiology*; D012590:Sclera; D014785:Vision, Ocular / Q000502:physiology