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Mineo Takagi, Hiroshi Oyamada, Haruki Abe, David S. Zee, Hiruma Hasebe, Atsushi Miki, Tomoaki Usui, Shigeru Hasegawa, Takehiko Bando; Adaptive Changes in Dynamic Properties of Human Disparity-Induced Vergence. Invest. Ophthalmol. Vis. Sci. 2001;42(7):1479-1486.
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purpose. Vergence eye movements undergo adaptive recalibration in response to a
training stimulus in which the initial disparity is changed just after
vergence begins (the double-step paradigm). In the present study the
changes in the dynamic properties of convergence, speed and
acceleration, were examined by using this double-step paradigm, before
and after adaptation.
methods. Four normal subjects participated. Three-dimensional visual stimuli
were provided by a head-mounted display with two liquid crystal diode
(LCD) panels. To induce adaptation, a double step of disparity was
used: an initial step from distances of 2 to 1 m was followed by a
second step to distances of 0.7 m (“increasing paradigm”) or
1.4 m (“decreasing paradigm”) after a constant period of 0.2
seconds. The dynamic properties of vergence were compared before and
after 30 minutes of training with these paradigms.
results. Peak velocity of convergence became significantly greater (increasing
paradigm) or smaller (decreasing paradigm) after 30 minutes’ training.
Changes in the dynamic properties of convergence were also obvious in
phase–plane (velocity versus position) and main sequence (peak
velocity versus amplitude) plots. Further analysis revealed that
adaptive increases in vergence velocity were accomplished by an
increase in the duration of the acceleration period, whereas adaptive
decreases were induced by a decrease in the maximum value of
conclusions. The pattern of change in the dynamic characteristics of vergence after
adaptation was similar to that of saccades and the initiation of
pursuit eye movements, suggesting common neural mechanisms for adaptive
changes in the open-loop control of eye
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