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) All Versions of this Article: 94/1/712    most recent 00093.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science 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 ISI Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Blohm, G. Articles by Lefèvre, P. Search for Related Content PubMed PubMed Citation Articles by Blohm, G. Articles by Lefèvre, P.

Direct Evidence for a Position Input to the Smooth Pursuit System

¹Centre for Systems Engineering and Applied Mechanics and ²Laboratory of Neurophysiology, Université catholique de Louvain, Brussels, Belgium; ³Centre for Vision Research, York University, Toronto, Ontario, Canada; and ⁴National Eye Institute, National Institutes of Health, Bethesda, Maryland

Submitted 25 January 2005; accepted in final form 17 February 2005

When objects move in our environment, the orientation of the visual axis in space requires the coordination of two types of eye movements: saccades and smooth pursuit. The principal input to the saccadic system is position error, whereas it is velocity error for the smooth pursuit system. Recently, it has been shown that catch-up saccades to moving targets are triggered and programmed by using velocity error in addition to position error. Here, we show that, when a visual target is flashed during ongoing smooth pursuit, it evokes a smooth eye movement toward the flash. The velocity of this evoked smooth movement is proportional to the position error of the flash; it is neither influenced by the velocity of the ongoing smooth pursuit eye movement nor by the occurrence of a saccade, but the effect is absent if the flash is ignored by the subject. Furthermore, the response started around 85 ms after the flash presentation and decayed with an average time constant of 276 ms. Thus this is the first direct evidence of a position input to the smooth pursuit system. This study shows further evidence for a coupling between saccadic and smooth pursuit systems. It also suggests that there is an interaction between position and velocity error signals in the control of more complex movements.

This article has been cited by other articles:

				J.-J. Orban de Xivry and P. Lefevre Saccades and pursuit: two outcomes of a single sensorimotor process J. Physiol., October 1, 2007; 584(1): 11 - 23. [Abstract] [Full Text] [PDF]

				A. A. Tarnutzer, S. Ramat, D. Straumann, and D. S. Zee Pursuit Responses to Target Steps During Ongoing Tracking J Neurophysiol, February 1, 2007; 97(2): 1266 - 1279. [Abstract] [Full Text] [PDF]