HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) An erratum has been published Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Takagi, M. Articles by Bando, T. Search for Related Content PubMed PubMed Citation Articles by Takagi, M. Articles by Bando, T.

Adaptive Changes in Dynamic Properties of Human Disparity-Induced Vergence

From the ¹ Department of Ophthalmology and ³ Physiology, Niigata University School of Medicine, Japan; ² Core Research for Evolutional Science and Technology, Japan Science and Technology, Saitama, Japan; and the ⁴ Department of Neurology, The Johns Hopkins Hospital, Baltimore, Maryland.

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.

This article has been cited by other articles:

				K. Arnoldi and J. D. Reynolds A Review of Convergence Insufficiency: What Are We Really Accomplishing with Exercises? Amer. Orthoptic Jrnl., January 1, 2007; 57(1): 123 - 130. [Abstract] [PDF]

				J. L. Semmlow and W. Yuan Adaptive Modification of Disparity Vergence Components: An Independent Component Analysis Study Invest. Ophthalmol. Vis. Sci., July 1, 2002; 43(7): 2189 - 2195. [Abstract] [Full Text] [PDF]