Abstract
Expectation of target motion is known to result in anticipatory smooth pursuit. Studies investigating prediction for smooth pursuit have often used simple stimuli like a translating dot. A recent study showed that anticipatory smooth pursuit can be triggered by global motion, using random dot kinematograms (RDK). Hence anticipatory pursuit does not require position information about an object moving across space (Santos et al 2012). However, this raises the question if this holds for prediction in general and if position information can improve predictive behavior (Heinen et al 2011,SfN). To investigate this, we used a single dot or a RDK stimulus as a pursuit target moving at 12[sup]o[/sup]/s in a blanking paradigm (Orban de Xivry et al 2006). On target reappearance after the blank, target velocity could be 12[sup]o[/sup]/s or 8[sup]o[/sup]/s or 16[sup]o[/sup]/s. Speed and target conditions were blocked to facilitate prediction on target reappearance. The results showed that the average anticipatory eye velocity at target initiation was 106% higher in blocks with dot stimulus (4.52±0.23[sup]o[/sup]/s) compared to blocks with RDK stimulus (2.19±0.11[sup]o[/sup]/s). Average anticipatory eye velocity at target reappearance after blank was 37% higher for dot stimulus (4.08±0.21[sup]o[/sup]/s) compared to RDK (2.98±0.15[sup]o[/sup]/s). Also, this anticipatory pursuit on target reappearance was scaled to target velocity after blank for the dot, but not for the RDK stimulus. Pursuit and saccadic displacements during blank were negatively correlated for both dot and RDK, with 29% higher saccadic displacement for dot compared to RDK and with similar pursuit displacements for both dot and RDK. These results suggest that position information from an object moving across space is not necessary, but dramatically improves the prediction for pursuit. This improvement is difficult to explain in the framework of gain modulation of eye velocity memory employed in the current models.
Meeting abstract presented at VSS 2013