Plastic Modification of Anti-Saccades: Adaptation of Saccadic Eye Movements Aimed at a Virtual Target

Abstract

Saccades allow us to visually explore our environment. Like other goal-directed movements, their accuracy is permanently controlled by adaptation mechanisms that, in the laboratory, can be induced by systematic displacement of the "real" visual target during the saccade. However, in an anti-saccade (AS) task, the target is "virtual" because gaze has to be shifted away from the "real" visual target toward its mentally defined mirror position. Here, we investigated whether the brain can adapt movements aimed at a virtual target by trying, for the first time, to adapt AS. Healthy human volunteers produced leftward AS during three different exposure phases in which a visual target provided feedback after the AS. In the adaptation condition, the feedback target appeared after completion of the AS response at a location shifted outward from final eye position (immediate non-veridical feedback). In the two control conditions, adaptation was prevented by delaying (800 ms) the shifted feedback target (delayed-shift) or by providing an immediate but veridical feedback at the mirror position of the visual target (no-shift). Results revealed a significant increase of AS gain only in the adaptation condition. Moreover, testing pro-saccades (PS) before and after exposure revealed a significant increase of leftward PS gain in the adaptation condition. This transfer of adaptation supports the hypotheses of a motor level of AS adaptation and of a visual level of AS vector inversion. Together with data from the literature, these results also provide new insights into adaptation and planning mechanisms for AS and for other subtypes of voluntary saccades.

New is always better: Novelty modulates oculomotor learning

“…These results lend further support to the recent discussion that saccadic adaptation involves more than a simple, automatic, error-based, low-level motor learning process (Collins & Wallman, 2012;Herman, Blangero, Madelain, Khan, & Harwood, 2013; LevyBencheton, Pisella, Salemme, Tilikete, & Pelisson, 2013;Madelain, Paeye, & Wallman, 2011;Meermeier et al, 2016;Panouilleres et al, 2014;Schütz & Souto, 2015;Zimmermann & Lappe, 2016). The top-down modulation on adaptation of scanning saccades observed in the present study may originate from frontal cortical areas or from the basal ganglia.…”

Spatial and temporal dynamics of presaccadic attentional facilitation before pro- and antisaccades

“…Journal of Vision, 18(11):2, 1-16, https://doi.org/10.1167/18.11.2. mme, Tilikete, & Pélisson, 2013;Munoz & Everling, 2004).…”

“…Separating the visual target location from the saccade goal of the motor plan is much more straightforward using saccadic adaptation protocols because adaptation results in a clear dissociation between the visual target location and the saccade goal motor plan. However, studies on saccadic adaptation have provided contradictory results (Collins & Doré-Mazars, 2006;Ditterich, Eggert, & Straube, 2000;Doré-Mazars & Collins, 2005;Khan, Heinen, & McPeek, 2010;Lévy-Bencheton et al, 2013;McFadden et al, 2002), which may be due to factors related to multiple possible levels of saccade adaptation (Pélisson, Alahyane, Panouillères, & Tilikete, 2010) rather than attentional-saccade linkage mechanisms. The dissociation between the target location and the saccade goal motor plan and the predictions of the two theories of attention are less straightforward for antisaccades because it is now acknowledged that during antisaccades tasks, there are in fact two motor plans in competition between each other-one is the motor plan to the target location (prosaccade) and the other is the plan to the location opposite to the target location (Massen, 2004;McPeek, Skavenski, & Nakayama, 2000).…”

The Effects of Short-Lasting Anti-Saccade Training in Homonymous Hemianopia with and without Saccadic Adaptation

“…However, since in HVFD patients the target cannot be presented in the blind hemifield, we choose to apply the above procedure to an anti-saccade (AS) task in which subjects have to perform a saccade toward the direction opposite (blind hemifield) to the hemifield where the visual target is presented (healthy hemifield), but with the same amplitude (Hallett, 1978 ). We recently described in normal subjects that a version of this task with an outward target shift (more eccentrically) occurring at the completion of the AS is capable of adaptively increasing the amplitude of anti-saccades (Lévy-Bencheton et al, 2013 ).…”