Migliaccio Americo A, Cremer Phillip D, Aw Swee T, Halmagyi G Michael, Curthoys Ian S, Minor Lloyd B, Todd Michael J
Eye and Ear Research Unit, Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney, Australia.
Exp Brain Res. 2003 Jul;151(2):238-48. doi: 10.1007/s00221-003-1447-z. Epub 2003 May 29.
The aim of this study was to determine whether vergence-mediated changes in the axis of eye rotation in the human vestibulo-ocular reflex (VOR) would obey Listing's Law (normally associated with saccadic eye movements) independent of the initial eye position. We devised a paradigm for disassociating the saccadic velocity axis from eye position by presenting near and far targets that were centered with respect to one eye. We measured binocular 3-dimensional eye movements using search coils in ten normal subjects and 3-dimensional linear head acceleration using Optotrak in seven normal subjects. The stimuli consisted of passive, unpredictable, pitch head rotations with peak acceleration of approximately 2000 degrees /s(2 )and amplitude of approximately 20 degrees. During the pitch head rotation, each subject fixated straight ahead with one eye, whereas the other eye was adducted 4 degrees during far viewing (94 cm) and 25 degrees during near viewing (15 cm). Our data showed expected compensatory pitch rotations in both eyes, and a vergence-mediated horizontal rotation only in the adducting eye. In addition, during near viewing we observed torsional eye rotations not only in the adducting eye but also in the eye looking straight ahead. In the straight-ahead eye, the change in torsional eye velocity between near and far viewing, which began approximately 40 ms after the start of head rotation, was 10+/-6 degrees /s (mean +/- SD). This change in torsional eye velocity resulted in a 2.4+/-1.5 degrees axis tilt toward Listing's plane in that eye. In the adducting eye, the change in torsional eye velocity between near and far viewing was 16+/-6 degrees /s (mean +/- SD) and resulted in a 4.1+/-1.4 degrees axis tilt. The torsional eye velocities were conjugate and both eyes partially obeyed Listing's Law. The axis of eye rotation tilted in the direction of the line of sight by approximately one-third of the angle between the line of sight and a line orthogonal to Listing's plane. This tilt was higher than predicted by the one-quarter rule. The translational acceleration component of the pitch head rotation measured 0.5 g and may have contributed to the increased torsional component observed during near viewing. Our data show that vergence-mediated eye movements obey a VOR/Listing's Law compromise strategy independent of the initial eye position.
本研究的目的是确定在人类前庭眼反射（VOR）中，由辐辏介导的眼球旋转轴变化是否会独立于初始眼位而遵循利斯廷定律（通常与眼球扫视运动相关）。我们设计了一种范式，通过呈现相对于一只眼睛居中的近和远目标，将扫视速度轴与眼位分离。我们使用搜索线圈测量了10名正常受试者的双眼三维眼球运动，并使用Optotrak测量了7名正常受试者的三维线性头部加速度。刺激包括被动、不可预测的俯仰头部旋转，峰值加速度约为2000度/s²，幅度约为20度。在俯仰头部旋转期间，每个受试者用一只眼睛直视前方，而另一只眼睛在远视力（94厘米）时内收4度，在近视力（15厘米）时内收25度。我们的数据显示，两只眼睛都有预期的补偿性俯仰旋转，并且只有内收眼有辐辏介导的水平旋转。此外，在近视力时，我们不仅在内收眼中观察到了眼球扭转旋转，在直视前方的眼睛中也观察到了。在直视前方的眼睛中，近视力和远视力之间眼球扭转速度的变化在头部旋转开始后约40毫秒开始，为10±6度/s（平均值±标准差）。这种眼球扭转速度的变化导致该眼的轴朝利斯廷平面倾斜2.4±1.5度。在内收眼中，近视力和远视力之间眼球扭转速度的变化为16±6度/s（平均值±标准差），导致轴倾斜4.1±1.4度。眼球扭转速度是共轭的，两只眼睛都部分遵循利斯廷定律。眼球旋转轴朝着视线方向倾斜，倾斜角度约为视线与垂直于利斯廷平面的线之间角度的三分之一。这种倾斜高于四分之一规则的预测值。俯仰头部旋转的平移加速度分量测量为0.5g，可能导致了在近视力时观察到的扭转分量增加。我们的数据表明，辐辏介导的眼球运动遵循一种独立于初始眼位的VOR/利斯廷定律折衷策略。
