THE RELATIONSHIP OF ANTICIPATORY SMOOTH EYE-MOVEMENT TO SMOOTH-PURSUIT INITIATION

We measured anticipatory smooth eye movements and smooth pursuit initi ation with predictable and unpredictable step-ramp stimuli in normal s ubjects. Subjects generated anticipatory eye motion before targets mov ed and during intervals when targets suddenly disappeared. Expectation s of target trajectory modified pursuit acceleration and latency, demo nstrating that pursuit initiation is not governed by visual inputs alo ne. Anticipatory smooth eye movements and predictive contributions to smooth pursuit had similar accelerations and velocities. Anticipation and pursuit initiation varied in parallel between subjects; anticipati on was stronger in subjects who generated faster smooth pursuit. These findings imply that anticipatory and smooth pursuit eye movements are governed by a common mechanism.