Human oculomotor system accounts for 3-D eye orientation in the visual-motor transformation for saccades.
Human oculomotor system accounts for 3-D eye orientation in the visual-motor transformation for saccades.
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DOI：
10.1152/jn.1998.80.5.2274
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发表时间：
1998-11
影响因子：
2.5
通讯作者：
E. M. Klier;J. Crawford
中科院分区：
文献类型：
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作者：
E. M. Klier;J. Crawford
最近的理论研究已经证明，视网膜刺激的几何形状中的三维（3-D）眼睛位置依赖性必须在神经上被考虑（即，在视觉参考系变换中），如果扫视从所有初始眼睛位置都是准确的并且服从Listing定律。我们的目标是确定人类眼跳生成器是否正确地实现了这种眼睛到头部的参考帧变换（RFT），或者它是否用视觉查找表（LT）来近似此功能。六名头部固定的受试者在完全黑暗中参与了三项实验。我们记录了在五对平行光之间的60度水平扫视，在+/-40度的垂直范围内（实验1），以及从中心目标的30度径向扫视，头部直立或顺时针/逆时针倾斜45度以诱导扭转眼球反滚，在双目和单眼观看条件下（实验2和3）。3-D眼睛取向和眼中心目标方向（即，视网膜误差）由右眼中的搜索线圈信号计算。实验1：如所预测的，视网膜误差是空间中的目标位移和3-D眼睛取向两者的非平凡函数（例如，水平移位的目标可能根据眼睛位置而引起水平或倾斜的视网膜误差）。这些数据被输入到一个3-D visualization LT模型，该模型实现了Listing定律，但预测了最终注视方向上高达19.8度的位置相关误差。实际的扫视服从Listing定律，但没有显示出最终注视方向的预测不准确模式，即，作为预测误差的函数，实际误差的斜率仅为-0. 01 +/- 0.14（与RFT模型的0和LT模型的1.0相比），表明对眼睛位置的近乎完美的补偿。实验2和3：来自初始扭转眼睛位置的实际方向误差仅是LT模型预测的一小部分（例如，例如，在一个实施例中，在双眼观察期间，顺时针方向为32%，逆时针方向为33%）。此外，任何残留的错误，立即减少视觉反馈时，在扫视。因此，除了扭转的零星误校准，扫视是准确的，从所有的3-D眼睛的位置。我们的结论是：1）一个视觉查找表的假设扫视未能考虑，甚至直接向视觉目标的扫视，而是，2）眼视系统考虑到三维眼睛的方向在一个视觉参考框架转换。这种转换可能是在视网膜定位组织的扫视中心（在皮层和上级丘）和脑干爆发发生器之间生理上实现的。
A recent theoretical investigation has demonstrated that three-dimensional (3-D) eye position dependencies in the geometry of retinal stimulation must be accounted for neurally (i.e., in a visuomotor reference frame transformation) if saccades are to be both accurate and obey Listing's law from all initial eye positions. Our goal was to determine whether the human saccade generator correctly implements this eye-to-head reference frame transformation (RFT), or if it approximates this function with a visuomotor look-up table (LT). Six head-fixed subjects participated in three experiments in complete darkness. We recorded 60 degrees horizontal saccades between five parallel pairs of lights, over a vertical range of +/-40 degrees (experiment 1), and 30 degrees radial saccades from a central target, with the head upright or tilted 45 degrees clockwise/counterclockwise to induce torsional ocular counterroll, under both binocular and monocular viewing conditions (experiments 2 and 3). 3-D eye orientation and oculocentric target direction (i.e., retinal error) were computed from search coil signals in the right eye. Experiment 1: as predicted, retinal error was a nontrivial function of both target displacement in space and 3-D eye orientation (e.g., horizontally displaced targets could induce horizontal or oblique retinal errors, depending on eye position). These data were input to a 3-D visuomotor LT model, which implemented Listing's law, but predicted position-dependent errors in final gaze direction of up to 19.8 degrees. Actual saccades obeyed Listing's law but did not show the predicted pattern of inaccuracies in final gaze direction, i.e., the slope of actual error, as a function of predicted error, was only -0. 01 +/- 0.14 (compared with 0 for RFT model and 1.0 for LT model), suggesting near-perfect compensation for eye position. Experiments 2 and 3: actual directional errors from initial torsional eye positions were only a fraction of those predicted by the LT model (e. g., 32% for clockwise and 33% for counterclockwise counterroll during binocular viewing). Furthermore, any residual errors were immediately reduced when visual feedback was provided during saccades. Thus, other than sporadic miscalibrations for torsion, saccades were accurate from all 3-D eye positions. We conclude that 1) the hypothesis of a visuomotor look-up table for saccades fails to account even for saccades made directly toward visual targets, but rather, 2) the oculomotor system takes 3-D eye orientation into account in a visuomotor reference frame transformation. This transformation is probably implemented physiologically between retinotopically organized saccade centers (in cortex and superior colliculus) and the brain stem burst generator.