Adaptive changes in dynamic properties of human disparity-induced vergence.

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 acceleration. 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 movements.

[1]  G K Hung,et al.  Quantitative assessment of disparity vergence components. , 1986, Investigative ophthalmology & visual science.

[2]  D S Zee,et al.  Effects of lesions of the oculomotor cerebellar vermis on eye movements in primate: smooth pursuit. , 2000, Journal of neurophysiology.

[3]  L. Dell’Osso,et al.  Saccadic system plasticity in humans , 1978, Annals of neurology.

[4]  L. Optican,et al.  Adaptive response to ocular muscle weakness in human pursuit and saccadic eye movements. , 1985, Journal of neurophysiology.

[5]  L. Optican,et al.  Cerebellar-dependent adaptive control of primate saccadic system. , 1980, Journal of neurophysiology.

[6]  J. Semmlow,et al.  Short term modification of disparity vergence eye movements , 1999, Vision Research.

[7]  D. Zee,et al.  Adaptive control of pursuit, vergence and eye torsion in humans: basic and clinical implications , 2001, Vision Research.

[8]  John L. Semmlow,et al.  ADAPTIVE RESPONSE DYNAMICS IN DISPARITY VERGENCE. , 1984 .

[9]  K Ukai,et al.  Changes in oculomotor functions before and after loading of a 3-D visually-guided task by using a head-mounted display. , 1996, Ergonomics.

[10]  T Anstis,et al.  Saccadic plasticity: parametric adaptive control by retinal feedback. , 1981, Journal of experimental psychology. Human perception and performance.

[11]  R Jones,et al.  Fusional vergence: sustained and transient components. , 1980, American journal of optometry and physiological optics.

[12]  Paul D. Gamlin,et al.  The role of cerebro-ponto-cerebellar pathways in the control of vergence eye movements , 1996, Eye.

[13]  G. Westheimer,et al.  Disjunctive eye movements , 1961, The Journal of physiology.

[14]  George K. Hung,et al.  Disparity vergence eye movements exhibit preprogrammed motor control , 1994, Vision Research.

[15]  D. Zee,et al.  Effects of lesions of the oculomotor vermis on eye movements in primate: saccades. , 1998, Journal of neurophysiology.

[16]  J. Semmlow,et al.  The influence of repetitive eye movements on vergence performance , 2000, Vision Research.

[17]  L. Stark,et al.  The main sequence, a tool for studying human eye movements , 1975 .