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) 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 Kumar, A. N. Articles by Leigh, R. J. Search for Related Content PubMed PubMed Citation Articles by Kumar, A. N. Articles by Leigh, R. J.

Properties of Anticipatory Vergence Responses

¹ From the Departments of Biomedical Engineering and ⁴ Neurology, Veterans Affairs Medical Center and University Hospitals, Case Western Reserve University, Cleveland, Ohio; the ² Department of Ophthalmology, Great Ormond Street Hospital for Children National Health Service Trust, and the ³ Department of Visual Science, Institute of Child Health, London, United Kingdom.

PURPOSE. To characterize the dynamic properties of vergence eye movements made between near and far targets that were alternately illuminated with predictable timing.

METHODS. Using the magnetic search coil technique, eye movements were measured in 10 normal subjects as they shifted their point of fixation between a near green LED and a distant red laser spot, both aligned on subjects’ midlines. Targets were alternately illuminated every 1.25 sec.

RESULTS. All subjects showed some anticipatory responses, consisting of vergence movements that preceded target jumps, accompanied by a small saccade. Group median anticipatory interval was 191 msec. Responses preceded target motion in 83% of divergence trials, and 70% of convergence trials. The velocities of both pre- and persaccadic components of anticipatory vergence responses were greater when the near target was positioned at 20-cm compared with at 36 cm. In control experiments, in which target presentation was unpredictable, vergence movements preceded stimuli in only approximately 2% of trials; for the group, vergence responses followed target presentation after a median interval of 183 msec. To determine whether anticipatory vergence movements depended on a memory of prior stimuli, trials were run in four subjects in which oddball stimuli required a different-sized vergence movement. Most responses to oddball stimuli were not significantly different from responses to the preceding stimuli.

CONCLUSIONS. Anticipatory vergence movements occur commonly in response to predictable stimulus movements in depth, but uncommonly when the timing of stimulus presentation is not predictable. The speed of anticipatory vergence movements is affected by stimulus amplitude. Properties of these movements are influenced by prior vergence responses, indicating that they depend on working memory.

This article has been cited by other articles:

				A. N. Kumar, Y. Han, L. F. Dell'osso, D. M. Durand, and R. J. Leigh Directional Asymmetry During Combined Saccade-Vergence Movements J Neurophysiol, May 1, 2005; 93(5): 2797 - 2808. [Abstract] [Full Text] [PDF]

				A. N. KUMAR, Y. H. HAN, K. LIAO, and R J. LEIGH Tests of Hering- and Helmholtz-Type Models for Saccade-Vergence Interactions by Comparing Visually Guided and Memory-Guided Movements Ann. N.Y. Acad. Sci., April 1, 2005; 1039(1): 466 - 469. [Abstract] [Full Text] [PDF]

				A. N. KUMAR, Y. H. HAN, and R. J. LEIGH Characteristics of a Range Effect for Vergence Movements Ann. N.Y. Acad. Sci., October 1, 2003; 1004(1): 394 - 398. [Full Text] [PDF]