title: Blinks slow memory-guided saccades.
abstract: Memory-guided saccades are slower than visually guided saccades. The usual explanation for this slowing is that the absence of a visual drive reduces the discharge of neurons in the superior colliculus. We tested a related hypothesis: that the slowing of memory-guided saccades was due also to the more frequent occurrence of gaze-evoked blinks with memory-guided saccades compared with visually guided saccades. We recorded gaze-evoked blinks in three monkeys while they performed visually guided and memory-guided saccades and compared the kinematics of the different saccade types with and without blinks. Gaze-evoked blinks were more common during memory-guided saccades than during visually guided saccades, and the well-established relationship between peak and average velocity for saccades was disrupted by blinking. The occurrence of gaze-evoked blinks was associated with a greater slowing of memory-guided saccades compared with visually guided saccades. Likewise, when blinks were absent, the peak velocity of visually guided saccades was only slightly higher than that of memory-guided saccades. Our results reveal interactions between circuits generating saccades and blink-evoked eye movements. The interaction leads to increased curvature of saccade trajectories and a corresponding decrease in saccade velocity. Consistent with this interpretation, the amount of saccade curvature and slowing increased with gaze-evoked blink amplitude. Thus, although the absence of vision decreases the velocity of memory-guided saccades relative to visually guided saccades somewhat, the cooccurrence of gaze-evoked blinks produces the majority of slowing for memory-guided saccades.
authors.affiliation: Department of Psychology, Stony Brook University, Stony Brook, NY 11794-2500, USA. alice.powers@stonybrook.edu
authors.forename: Alice S
authors.initials: AS
authors.lastname: Powers
authors.forename: Michele A
authors.initials: MA
authors.lastname: Basso
authors.forename: Craig
authors.initials: C
authors.lastname: Evinger
mesh_terms: D000200:Action Potentials; D000818:Animals; D001696:Biomechanical Phenomena; D001767:Blinking / Q000502:physiology*; D008253:Macaca mulatta; D008568:Memory / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology; D009474:Neurons / Q000502:physiology; D010775:Photic Stimulation; D012438:Saccades / Q000502:physiology*; D013477:Superior Colliculi / Q000166:cytology / Q000502:physiology