Tian Jun-Ru, Crane Benjamin T, Ishiyama Akira, Demer Joseph L
Department of Ophthalmology, University of California, Los Angeles, CA 90095-7002, USA.
Exp Brain Res. 2007 Sep;182(2):143-55. doi: 10.1007/s00221-007-0977-1. Epub 2007 Jun 5.
Saccades executed with the head stationary have kinematics conforming to Listing's law (LL), confining the ocular rotational axis to Listing's plane (LP). In unilateral vestibular deafferentation (UVD), the vestibulo-ocular reflex (VOR), which does not obey LL, has at high head acceleration a slow phase that has severely reduced velocity during ipsilesional rotation, and mildly reduced velocity during contralesional rotation. Studying four subjects with chronic UVD using 3D magnetic search coils, we investigated kinematics of stereotypic rapid eye movements that supplement the impaired VOR. We defined LP with the head immobile, and expressed eye and head movements as quaternions in LP coordinates. Subjects underwent transient whole body yaw at peak acceleration 2,800 degrees /s(2) while fixating targets centered, or 20 degrees up or down prior to rotation. The VOR shifted ocular torsion out of LP. Vestibular catch-up saccades (VCUS) occurred with mean latency 90 +/- 44 ms (SD) from ipsilesional rotation onset, maintained initial non-LL torsion so that their quaternion trajectories paralleled LP, and had velocity axes changing by half of eye position. During contralesional rotation, rapid eye movements occurred at mean latency 135 +/- 36 ms that were associated with abrupt decelerations (ADs) of the horizontal slow phase correcting 3D deviations in its velocity axis, with quaternion trajectories not paralleling LP. Rapid eye movements compensating for UVD have two distinct kinematics. VCUS have velocity axis dependence on eye position consistent with LL, so are probably programmed in 2D by neural circuits subserving visual saccades. ADs have kinematics that neither conform to LL nor match the VOR axis, but appear instead programmed in 3D to correct VOR axis errors.
头部静止时执行的扫视运动其运动学符合利斯廷定律（LL），将眼旋转轴限制在利斯廷平面（LP）内。在单侧前庭传入神经切断术（UVD）中，不遵循LL的前庭眼反射（VOR）在高头部加速度时，同侧旋转期间慢相速度严重降低，对侧旋转期间速度轻度降低。我们使用3D磁性搜索线圈研究了4名慢性UVD患者，以调查补充受损VOR的刻板快速眼动的运动学。我们在头部静止时定义LP，并在LP坐标中以四元数表示眼和头部运动。受试者在峰值加速度为2800度/s²时进行短暂全身偏航，同时注视中心目标，或在旋转前向上或向下20度的目标。VOR使眼扭转偏离LP。前庭追赶扫视（VCUS）在同侧旋转开始后平均潜伏期90±44毫秒（标准差）出现，保持初始非LL扭转，使其四元数轨迹平行于LP，并且速度轴随眼位置变化一半。在对侧旋转期间，快速眼动在平均潜伏期135±36毫秒时出现，与水平慢相的突然减速（ADs）相关，纠正其速度轴上的3D偏差，四元数轨迹不平行于LP。补偿UVD的快速眼动有两种不同的运动学。VCUS的速度轴对眼位置的依赖性与LL一致，因此可能由服务于视觉扫视的神经回路在二维中编程。ADs的运动学既不符合LL也不匹配VOR轴，而是似乎在三维中编程以纠正VOR轴误差。
