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: 91/2/890    most recent 00818.2003v1 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 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 Web of Science (17) Citing Articles via Google Scholar Google Scholar Articles by Arai, K. Articles by Keller, E. L. Search for Related Content PubMed PubMed Citation Articles by Arai, K. Articles by Keller, E. L.

Properties of Saccadic Responses in Monkey When Multiple Competing Visual Stimuli Are Present

The Smith-Kettlewell Eye Research Institute, San Francisco, California 94115

Submitted 20 August 2003; accepted in final form 10 October 2003

Important insights into the neural organization of the saccadic system have been gained when the usually stereotyped movement trajectories of saccades have been altered by experimental manipulation. In the present study we produced trajectory variability in monkeys by using a visual search task in which both the location and color of an odd-colored target were changed randomly trial by trial, and the number of distractors was varied on each trial. We wished to determine whether increasing the number of distractors also increased the movement trajectory variation, i.e., the amount of initial directional deviation, endpoint deviation (averaging), and curvature of saccades. Overall, saccade latencies and the proportion of saccades directed to distractors decreased as the number of homogenous distractors increased. We also found that saccades have much more dispersion in their initial direction when distractors are present in comparison to the case when only a single target without distractors appears. However, initial dispersion decreases systematically as the number of distractors increases. The percentage of averaging saccades produced in the search task was not consistently dependent on the number of distractors. A significant fraction of averaging saccades still occurred for much wider spatial separations of stimuli than in previous studies using two visual stimuli with no specified target. The curvature of saccade trajectories increased dramatically when distractors were present, but the amount of curvature was not systematically affected by the number of distractors. Errors present in saccade trajectory in the search task were only poorly compensated. We conclude that these variable saccade trajectories result from incomplete or inaccurate specification of the target when competing stimuli are present and that a smaller number of more widely spread distractors facilitate saccade variability, perhaps due to the greater difficulty of target selection.

This article has been cited by other articles:

				J.-H. Song and R. M. McPeek Eye-Hand Coordination During Target Selection in a Pop-Out Visual Search J Neurophysiol, November 1, 2009; 102(5): 2681 - 2692. [Abstract] [Full Text] [PDF]

				R. M. McPeek Reversal of a Distractor Effect on Saccade Target Selection After Superior Colliculus Inactivation J Neurophysiol, May 1, 2008; 99(5): 2694 - 2702. [Abstract] [Full Text] [PDF]

				J.-H. Song, N. Takahashi, and R. M. McPeek Target Selection for Visually Guided Reaching in Macaque J Neurophysiol, January 1, 2008; 99(1): 14 - 24. [Abstract] [Full Text] [PDF]

				R. M. McPeek Incomplete Suppression of Distractor-Related Activity in the Frontal Eye Field Results in Curved Saccades J Neurophysiol, November 1, 2006; 96(5): 2699 - 2711. [Abstract] [Full Text] [PDF]

				M. Watanabe, Y. Kobayashi, Y. Inoue, and T. Isa Effects of Local Nicotinic Activation of the Superior Colliculus on Saccades in Monkeys J Neurophysiol, January 1, 2005; 93(1): 519 - 534. [Abstract] [Full Text] [PDF]