Institute for Psychology, University of Münster, Münster, Germany.
Otto-Creutzfeldt Center for Cognitive and Behavioural Neuroscience, University of Münster, Münster, Germany.
J Neurophysiol. 2023 Nov 1;130(5):1334-1343. doi: 10.1152/jn.00021.2023. Epub 2023 Oct 25.
Vision requires that we rotate our eyes frequently to look at informative structures in the scene. Eye movements are planned by the brain but their execution depends on the mechanical properties of the oculomotor plant, that is, the arrangement of eyeball position, muscle insertions, and pulley locations. Therefore, the biomechanics of rotations is sensitive to eyeball translation because it changes muscle levers. Eyeball translations are little researched as they are difficult to measure with conventional techniques. Here, we investigated the effects of eyeball translation on the coordination of eyeball rotation by high-speed MRI recordings of saccadic eye movements during blinks, which are known to produce strong translations. We found that saccades during blinks massively overshoot their targets and that these overshoots occur in a transient fashion such that the gaze is back on target at the time the blink ends. These dynamic overshoots were tightly coupled to the eyeball translation, both in time and in size. Saccades made without blinks were also accompanied by small amounts of transient eyeball retraction, the size of which scaled with saccade amplitude. These findings demonstrate a complex combination of rotation and translation of the eye. The mechanical consequences of eyeball translation on oculomotor control should be considered along with the neural implementation in the brainstem to understand the generation of eye movements and their disorders. We found that saccades during blinks can massively overshoot their target when the eyeball is retracted. Our data imply that the overshoots are not part of the saccade plan prepared in the brainstem, but instead a consequence of the altered biomechanics resulting from concurrent eyeball translation and rotation. To our best knowledge, this is the first direct observation of dynamic properties of the oculomotor plant altering the execution of rotational eye movements.
视觉要求我们频繁转动眼睛以观察场景中的信息结构。眼球运动由大脑规划，但它们的执行取决于眼动器官的机械特性，即眼球位置、肌肉插入和滑轮位置的排列。因此，眼球旋转的生物力学对眼球平移很敏感，因为它改变了肌肉杠杆。眼球平移研究较少，因为它们很难用常规技术测量。在这里，我们通过高速 MRI 记录眨眼期间的扫视眼动，研究了眼球平移对眼球旋转协调的影响，因为众所周知眨眼会产生强烈的平移。我们发现，眨眼期间的扫视会严重偏离目标，并且这些偏离是瞬态的，即在眨眼结束时，注视会回到目标上。这些动态偏离与眼球平移在时间和大小上都紧密耦合。没有眨眼的扫视也伴随着少量的瞬态眼球回缩，其大小与扫视幅度成正比。这些发现表明眼球的旋转和平移是一种复杂的组合。眼球平移对眼动控制的机械后果应与脑干中的神经实现一起考虑，以了解眼动的产生及其障碍。我们发现，当眼球回缩时，眨眼期间的扫视会严重偏离目标。我们的数据表明，这些偏离不是脑干中准备好的扫视计划的一部分，而是由于眼球平移和旋转同时发生而改变的生物力学的结果。据我们所知，这是第一次直接观察到眼动器官的动态特性改变旋转眼动的执行。
