Direction-dependent distortions of retinocentric space in the visuomotor transformation for pointing
Direction-dependent distortions of retinocentric space in the visuomotor transformation for pointing
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DOI：
10.1007/s002210000340
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发表时间：
2000-05-01
影响因子：
2
通讯作者：
Crawford, JD
中科院分区：
文献类型：
--
作者：
Henriques, DYP;Crawford, JD
这项研究的目的是：(1)量化开环指向空间中心(但视网膜周围)视觉目标的误差，并在不同偏心的水平、垂直和倾斜方向上保持凝视；以及(2)确定这些误差的计算来源。通过使用搜索线圈测量眼睛和手臂的方向，而六名头部固定的受试者在完全黑暗的情况下看着并指向记忆中的目标。平均而言，受试者在视网膜移位的垂直和水平部分(相对于当前的凝视有超过目标的倾向)都有轻微的夸大，但个别受试者在这种模式上表现出相当大的差异。此外，斜视视网膜靶点的指向误差只能从基本方向的误差中部分预测，这表明大多数误差不是在独立的垂直和水平坐标通道内产生的，其余的方差与读出视网膜移位的大小和方向时的非均匀、方向相关的失真有关。最大和最一致的不均匀性发生在跨越视网膜空间垂直经线的相邻点之间的不连续，可能与左右两列空间表示之间的断裂有关。这些发现与这样的假设相一致，即这些视觉运动扭曲中至少有一些是由于准独立的视觉运动读出机制对视网膜原位空间的“斑块”的错误校准，在某些解剖和/或生理边界的斑块之间存在严重的不连续。
The aim of this study was to: (1) quantify errors in open-loop pointing toward a spatially central (but retinally peripheral) visual target with gaze maintained in various eccentric horizontal, vertical, and oblique directions; and (2) determine the computational source of these errors. Eye and arm orientations were measured with the use of search coils while six head-fixed subjects looked and pointed toward remembered targets in complete darkness. On average, subjects made small exaggerations in both the vertical and horizontal components of retinal displacement (tending to overshoot the target relative to current gaze), but individual subjects showed considerable variations in this pattern. Moreover, pointing errors for oblique retinal targets were only partially predictable from errors for the cardinal directions, suggesting that most of these errors did not arise within independent vertical and horizontal coordinate channels The remaining variance was related to nonhomogeneous, direction-dependent distortions in reading out the magnitudes and directions of retinal displacement. The largest and most consistent nonhomogeneities occurred as discontinuities between adjacent points across the vertical meridian of retinotopic space, perhaps related to the break between the representations of space in the left and right col tices. These findings are consistent with the hypothesis that at least some of these visuomotor distortions are due to miscalibrations in quasi-independent visuomotor readout mechanisms for "patches" of retinotopic space, with major discontinuities existing between patches at certain anatomic and/or physiological borders.