Rambold Holger, El Baz Ieman, Helmchen Christoph
Department of Neurology, University of Luebeck, Ratzeburger Allee 160, 23538 Luebeck, Germany.
Exp Brain Res. 2005 Feb;161(1):11-26. doi: 10.1007/s00221-004-2040-9. Epub 2004 Oct 9.
Blinks are known to affect eye movements, e.g., saccades, slow and fast vergence, and saccade-vergence interaction, in two ways: by superimposition of blink-associated eye movements and changes of the central premotor activity in the brainstem. The goal of this study was to determine, for the first time, the effects of trigeminal evoked blinks on ongoing smooth pursuit eye movements which could be related to visual sensory or premotor neuronal changes. This was compared to the effect of a target disappearing for 100-300 ms duration during ongoing smooth pursuit (blank paradigm) in order to control for the visual sensory effects of a blink. Eye and blink movements were recorded in eight healthy subjects with the scleral search coil technique. Blink-associated eye movements during the first 50% of the blink duration were non-linearly superimposed on the smooth pursuit eye movements. Immediately after the blink-associated eye movements, the pursuit velocity slowly decreased by an average of 3.2+/-2.1 degrees /s. This decrease was not dependent on the stimulus direction. The pursuit velocity decrease caused by blinks which occluded the pupil more than 50% could be explained mostly by blanking the visual target. However, small blinks that did not occlude the pupil (<10% of lid closure) also decreased smooth pursuit velocity. Thus, this blink effect on pursuit velocity cannot be explained by blink-associated eye movements or by the blink having blanked the visual input. We propose that part of this effect might either be caused by incomplete visual suppression during blinks and/or a change in the activity of omnipause neurons.
众所周知，眨眼会通过两种方式影响眼球运动，例如扫视、慢速和快速集合以及扫视 - 集合相互作用：一是与眨眼相关的眼球运动叠加，二是脑干中中枢运动前活动的变化。本研究的目的是首次确定三叉神经诱发眨眼对正在进行的平稳跟踪眼球运动的影响，这可能与视觉感觉或运动前神经元变化有关。将其与在平稳跟踪过程中目标消失100 - 300毫秒（空白范式）的效果进行比较，以控制眨眼的视觉感觉影响。使用巩膜搜索线圈技术记录了8名健康受试者的眼球和眨眼运动。在眨眼持续时间的前50%内，与眨眼相关的眼球运动以非线性方式叠加在平稳跟踪眼球运动上。在与眨眼相关的眼球运动之后，跟踪速度立即缓慢下降，平均下降3.2±2.1度/秒。这种下降不依赖于刺激方向。瞳孔遮挡超过50%的眨眼所导致的跟踪速度下降，主要可以通过视觉目标消失来解释。然而，未遮挡瞳孔的小眨眼（眼睑闭合小于10%）也会降低平稳跟踪速度。因此，这种对跟踪速度的眨眼效应不能用与眨眼相关的眼球运动或眨眼使视觉输入消失来解释。我们提出，这种效应的一部分可能是由眨眼期间不完全的视觉抑制和/或全暂停神经元活动的变化引起的。
