Abstract
Introduction: Saccade adaptation can be contextual: maintaining two different gain (saccade/target amplitude) parameters for the same vector. For example, different orbital positions can serve as contexts for separate gain states. We have previously shown that even visual properties of the target can also be used as a context, implying a general form of associative learning. We hypothesize that a more specific natural use of contextual saccade adaptation might be in adapting saccades to moving targets. In this study, we explore using different direction of movement as a context for saccade adaptation for the first time. Methods: While maintaining central fixation, 10 subjects viewed a circularly moving target (1/16 Hz, clockwise or counterclockwise) at 8-10 degrees eccentricity in the upper right quadrant. When the target was in a sector between 15 and 75 degrees, the fixation point disappeared and subjects initiated a saccade to the moving target, which remained visible for 400ms post-saccade. After a baseline phase, clockwise targets were stepped outward by 2 degrees upon saccades, and counterclockwise targets stepped inward by 2 degrees. Results: During the baseline phase, we found no gain differences in saccades to the oppositely moving targets. In 9/10 subjects, the adaptation phase induced gradual and significant contextual adaptation of saccades: same vector saccades either increased or decreased their gains to clockwise or counterclockwise targets, respectively. These differences persisted in a post-adaptation phase. Conclusion: We conclude that motion direction can act as a strong contextual cue for saccade adaptation. This contextual adaptation can assist in extrapolating visual motion information in coordinating saccadic and smooth eye movements.
Meeting abstract presented at VSS 2013