Donders Inst. for Brain, Cognition and Behaviour, Dept. of Biophysics, Radboud Univ. Nijmegen Medical Ctr., G. Grooteplein 21, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
J Neurophysiol. 2010 Mar;103(3):1685-95. doi: 10.1152/jn.00788.2009. Epub 2010 Feb 3.
Studies in both humans and monkeys have indicated that blinks affect the central programming of saccades. In this study, we compared the influence of two types of reflex blinks on the trajectories and kinematics of memory-guided saccades in human subjects. We found that electrical stimulation of the supraorbital nerve shortly before or during a saccade briefly halts or decelerates the eye in midflight. After this short interruption, the eye always resumed its course and reached the target location in the absence of visual feedback. Air puff stimuli produced significant decreases in mean eye velocity too, but in addition to these changes in saccade kinematics, they produced much larger and more variable perturbations of the two-dimensional saccade trajectories. Even so, the endpoints of blink-perturbed saccades obtained under both test conditions remained as accurate and as precise as those observed in the control condition. We hypothesize that the reduction in mean eye velocity is not caused by a trigeminal reactivation of brain stem omnipause neurons but could instead arise from a trigeminal transient inhibition of saccade-related activity in the midbrain superior colliculus (SC). These findings support the theory that blink-perturbed saccades are programmed as slow, but straight, saccades onto which blink-related eye movements are superimposed. This linear superposition occurs downstream from the SC.
在人类和猴子中的研究表明眨眼会影响扫视的中枢编程。在这项研究中，我们比较了两种类型的反射性眨眼对人类被试者记忆引导性扫视轨迹和运动学的影响。我们发现，在扫视前或扫视期间对眶上神经进行电刺激会使眼球在中途短暂停止或减速。短暂中断后，眼球总是会恢复到原来的路径并到达没有视觉反馈的目标位置。气吹刺激也会显著降低平均眼动速度，但除了扫视运动学的这些变化外，它们还会对二维扫视轨迹产生更大且更可变的干扰。即便如此，在两种测试条件下获得的眨眼干扰扫视的终点与在对照条件下观察到的一样准确和精确。我们假设平均眼动速度的降低不是由于脑干 omnipause 神经元的三叉神经再激活引起的，而是三叉神经对中脑上丘与扫视相关的活动的短暂抑制所致。这些发现支持了这样一种理论，即眨眼干扰的扫视被编程为缓慢但直接的扫视，其上叠加了与眨眼相关的眼球运动。这种线性叠加发生在上丘的下游。
