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1 CESAME, Universite catholique de Louvain, Louvain-la-Neuve, Belgium; Laboratory of Neurophysiology, Universite catholique de Louvain, Brussels, Belgium
2 Laboratory of Neurophysiology, Universite catholique de Louvain, Brussels, Belgium
* To whom correspondence should be addressed. E-mail: lefevre{at}csam.ucl.ac.be.
A saccade triggered during sustained smooth pursuit is programmed using retinal information about the relative position and velocity of the target with respect to the eye (de Brouwer, et al. 2002). Thus, the smooth pursuit and saccadic systems are coordinated by using common retinal inputs. Yet, in the absence of retinal information about the relative motion of the eye with respect to the target, the question arises whether the smooth and saccadic systems are still able to be coordinated possibly by using extraretinal information to account for the saccadic and smooth eye movements. To address this question, we flashed a target during smooth anticipatory eye movements in darkness and the subjects were asked to orient their visual axis to the remembered location of the flash. We observed multiple orientation saccades (typically 2-3) towards the memorized location of the flash. The first orienting saccade was programmed using only the position error at the moment of the flash and the smooth eye movement was ignored. However, subsequent saccades executed in darkness compensated gradually for the smooth eye displacement (mean compensation 
70%). This behavior revealed a 400ms delay in the time course of orientation for the compensation of the ongoing smooth eye displacement. We conclude that extraretinal information about the smooth motor command is available to the saccadic system in the absence of visual input. There is a 400ms delay for smooth movement integration, saccade programming and execution.
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