Department of Clinical Neuroscience, Division of Eye and Vision, Marianne Bernadotte Centre, Karolinska Institutet, Stockholm, Sweden.
St Erik Eye Hospital, Stockholm, Sweden.
Exp Brain Res. 2024 Jun;242(6):1469-1479. doi: 10.1007/s00221-024-06842-7. Epub 2024 May 2.
Ocular torsion and vertical divergence reflect the brain's sensorimotor integration of motion through the vestibulo-ocular reflex (VOR) and the optokinetic reflex (OKR) to roll rotations. Torsion and vergence however express different response patterns depending on several motion variables, but research on their temporal dynamics remains limited. This study investigated the onset times of ocular torsion (OT) and vertical vergence (VV) during visual, vestibular, and visuovestibular motion, as well as their relative decay rates following prolonged optokinetic stimulations. Temporal characteristics were retrieved from three separate investigations where the level of visual clutter and acceleration were controlled. Video eye-tracking was used to retrieve the eye-movement parameters from a total of 41 healthy participants across all trials. Ocular torsion consistently initiated earlier than vertical vergence, particularly evident under intensified visual information density, and higher clutter levels were associated with more balanced decay rates. Additionally, stimulation modality and accelerations affected the onsets of both eye movements, with visuovestibular motion triggering earlier responses compared to vestibular motion, and increased accelerations leading to earlier onsets for both movements. The present study showed that joint visuovestibular responses produced more rapid onsets, indicating a synergetic sensorimotor process. It also showed that visual content acted as a fusional force during the decay period, and imposed greater influence over the torsional onset compared to vergence. Acceleration, by contrast, did not affect the temporal relationship between the two eye movements. Altogether, these findings provide insights into the sensorimotor integration of the vestibulo-ocular and optokinetic reflex arcs.
眼扭转和垂直聚散反映了大脑通过前庭眼反射（VOR）和视动反射（OKR）对滚动旋转进行运动感觉综合的能力。然而，扭转和聚散根据几个运动变量表现出不同的反应模式，但对其时间动力学的研究仍然有限。本研究调查了在视觉、前庭和视动运动期间眼扭转（OT）和垂直聚散（VV）的起始时间，以及在长时间视动刺激后它们的相对衰减率。通过三个单独的研究检索了时间特征，这些研究控制了视觉杂乱程度和加速度的水平。视频眼跟踪用于从总共 41 名健康参与者的所有试验中检索眼动参数。眼扭转始终比垂直聚散更早开始，在视觉信息密度增强和杂乱水平较高的情况下尤其明显。此外，刺激方式和加速度会影响两种眼动的起始，视动刺激比前庭刺激更早触发反应，加速度增加会使两种运动的起始更早。本研究表明，联合视动反应产生更快的起始，表明存在协同的感觉运动过程。它还表明，在衰减期间，视觉内容充当融合力，对扭转起始的影响比对聚散的影响更大。相比之下，加速度不会影响两个眼动之间的时间关系。总之，这些发现为前庭眼反射和视动反射弧的感觉运动综合提供了深入了解。
