Abstract
Anticipatory smooth pursuit eye movements can be elicited by cues that signal the future direction of target motion (e.g., Santos et. al., 2012). A comparison of the effectiveness of cues, and their sensitivity to temporal parameters such as duration or delay, could shed light on mechanisms responsible for initiating anticipatory pursuit. Subjects pursued a disc that moved (170'/s) inside an inverted Y-shaped tube. The disc could travel down either right or left oblique branch of the tube (p=.5). Three cues were tested: (1) Natural: barrier that blocked the untraveled branch; (2) Arbitrary/local: bar at the top of the tube indicated the branch by being on the same side. (3) Arbitrary/global: color of the tube (red or green) indicated the branch. Cue type affected anticipatory pursuit. Horizontal eye velocity at the time the disc entered the oblique branch was approximately twice as fast for the natural barrier cue than either arbitrary cue. Timing of cue presentation also affected anticipatory pursuit. Delaying the presentation of the cue until the disc approached the choice point had a similar effect on all cues. Anticipatory eye velocities decreased when the cue was available <200ms before it entered the branch. Removing the cues after the onset of target motion (so that only memory of the cue was available) had different effects depending on cue type. While removal of arbitrary cues had no effect, anticipatory pursuit was reduced substantially when the barrier cue was removed >100ms before the disc entered the branch. Anticipatory eye movements were reduced to levels found for the arbitrary cues. These results suggest that there are different mechanisms generating anticipatory smooth eye movements. One mechanism may depend on arbitrary associations that can be learned. Another mechanism evoked by naturalistic cues, such as the barrier, may be responsible for producing higher anticipatory eye velocities.
Meeting abstract presented at VSS 2014