Kwon Sunwoo, Rolfs Martin, Mitchell Jude F
Brain and Cognitive Sciences, University of Rochester, Rochester, NY, USA.
Center for Visual Science, University of Rochester, Rochester, NY, USA.
J Vis. 2019 Sep 3;19(11):12. doi: 10.1167/19.11.12.
Saccadic eye movements sample the visual world and ensure high acuity across the visual field. To compensate for delays in processing, saccades to moving targets require predictions: The eyes must intercept the target's future position to then pursue its direction of motion. Although prediction is crucial to voluntary pursuit, it is unclear whether it is an obligatory feature of saccade planning. Saccade planning involves an involuntary enhanced processing of the target, called presaccadic attention. Does this presaccadic attention recruit smooth eye movements automatically? To test this, we had human participants perform a saccade to one of four apertures, which were static, but each contained a random dot field with motion tangential to the required saccade. In this task, saccades were deviated along the direction of target motion, and the eyes exhibited a following response upon saccade landing. This postsaccadic following response (PFR) increased with spatial uncertainty of the target position and persisted even when we removed the motion stimulus in midflight of the saccade, confirming that it relied on presaccadic information. Motion from 50-100 ms prior to the saccade had the strongest influence on PFR, consistent with the time course of perceptual enhancements reported in presaccadic attention. Finally, the PFR magnitude related linearly to the logarithm of stimulus velocity and generally had low gain, similar to involuntary ocular following movements commonly observed after sudden motion onsets. These results suggest that presaccadic attention selects motion features of targets predictively, presumably to ensure successful immediate tracking of saccade targets in motion.
扫视眼动对视觉世界进行采样，并确保整个视野的高敏锐度。为了补偿处理延迟，对移动目标的扫视需要预测：眼睛必须拦截目标的未来位置，然后追踪其运动方向。尽管预测对于自主追踪至关重要，但尚不清楚它是否是扫视计划的一个必然特征。扫视计划涉及对目标的一种非自愿的增强处理，称为扫视前注意。这种扫视前注意是否会自动引发平稳眼动？为了测试这一点，我们让人类参与者向四个光圈之一进行扫视，这些光圈是静止的，但每个光圈都包含一个随机点场，其运动方向与所需扫视方向相切。在这个任务中，扫视沿着目标运动方向发生偏差，并且眼睛在扫视着陆时表现出跟随反应。这种扫视后跟随反应（PFR）随着目标位置的空间不确定性增加而增强，并且即使在扫视中途移除运动刺激时仍然持续，这证实了它依赖于扫视前信息。扫视前50 - 100毫秒的运动对PFR的影响最强，这与扫视前注意中报告的感知增强的时间进程一致。最后，PFR的大小与刺激速度的对数呈线性关系，并且通常增益较低，类似于在突然运动开始后常见的非自愿眼球跟随运动。这些结果表明，扫视前注意会预测性地选择目标的运动特征，大概是为了确保成功即时追踪运动中的扫视目标。
