Department of Psychology, Stony Brook University, Stony Brook, NY 11794-2500, USA.
J Neurophysiol. 2013 Feb;109(3):734-41. doi: 10.1152/jn.00746.2012. Epub 2012 Nov 14.
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.
记忆引导的眼跳比视觉引导的眼跳慢。对于这种减速的常见解释是，没有视觉驱动会减少上丘神经元的放电。我们测试了一个相关的假设：即记忆引导的眼跳减速也归因于与视觉引导的眼跳相比，记忆引导的眼跳中更频繁地出现注视诱发的眨眼。当猴子执行视觉引导和记忆引导的眼跳时，我们记录了注视诱发的眨眼，并比较了有眨眼和无眨眼的不同眼跳类型的运动学。与视觉引导的眼跳相比，记忆引导的眼跳中注视诱发的眨眼更为常见，并且眨眼会破坏眼跳的峰值和平均速度之间的既定关系。注视诱发的眨眼的发生与记忆引导的眼跳相比，与视觉引导的眼跳相比，记忆引导的眼跳减速更大。同样，当没有眨眼时，视觉引导的眼跳的峰值速度仅略高于记忆引导的眼跳的峰值速度。我们的结果揭示了产生眼跳和眨眼诱发的眼球运动的回路之间的相互作用。这种相互作用导致眼跳轨迹的曲率增加，相应地导致眼跳速度降低。与这种解释一致，眼跳曲率和减速的量随着注视诱发的眨眼幅度增加而增加。因此，尽管视觉缺失会使记忆引导的眼跳速度相对于视觉引导的眼跳速度略有降低，但注视诱发的眨眼的共同发生导致了记忆引导的眼跳的大部分减速。
