Dowiasch Stefan, Blanke Marius, Knöll Jonas, Bremmer Frank
Department Neurophysics, Philipps-Universität Marburg, Marburg, Germany.
Center for Mind, Brain and Behavior (CMBB), Philipps-Universität Marburg and Justus-Liebig-Universität Gießen, Gießen, Germany.
Front Neurosci. 2023 Feb 2;17:1058340. doi: 10.3389/fnins.2023.1058340. eCollection 2023.
Numerous previous studies have shown that eye movements induce errors in the localization of briefly flashed stimuli. Remarkably, the error pattern is indicative of the underlying eye movement and the exact experimental condition. For smooth pursuit eye movements (SPEM) and the slow phase of the optokinetic nystagmus (OKN), perceived stimulus locations are shifted in the direction of the ongoing eye movement, with a hemifield asymmetry observed only during SPEM. During the slow phases of the optokinetic afternystagmus (OKAN), however, the error pattern can be described as a perceptual expansion of space. Different from SPEM and OKN, the OKAN is an open-loop eye movement.
Visually guided smooth pursuit can be transformed into an open-loop eye movement by briefly blanking the pursuit target (gap). Here, we examined flash localization during open-loop pursuit and asked, whether localization is also prone to errors and whether these are similar to those found during SPEM or during OKAN. Human subjects tracked a pursuit target. In half of the trials, the target was extinguished for 300 ms (gap) during the steady-state, inducing open-loop pursuit. Flashes were presented during this gap or during steady-state (closed-loop) pursuit.
In both conditions, perceived flash locations were shifted in the direction of the eye movement. The overall error pattern was very similar with error size being slightly smaller in the gap condition. The differences between errors in the open- and closed-loop conditions were largest in the central visual field and smallest in the periphery.
We discuss the findings in light of the neural substrates driving the different forms of eye movements.
此前众多研究表明，眼球运动会在短暂闪现刺激的定位中引发误差。值得注意的是，误差模式能反映潜在的眼球运动及确切的实验条件。对于平稳跟踪眼球运动（SPEM）和视动性眼震（OKN）的慢相，所感知到的刺激位置会沿正在进行的眼球运动方向发生偏移，仅在SPEM期间观察到半视野不对称。然而，在视动性后眼震（OKAN）的慢相期间，误差模式可被描述为空间的感知扩展。与SPEM和OKN不同，OKAN是一种开环眼球运动。
通过短暂遮挡跟踪目标（间隙），视觉引导的平稳跟踪可转变为开环眼球运动。在此，我们研究了开环跟踪期间的闪光定位，并询问定位是否也容易出错，以及这些错误是否与SPEM或OKAN期间发现的错误相似。人类受试者跟踪一个跟踪目标。在一半的试验中，目标在稳态期间熄灭300毫秒（间隙），从而引发开环跟踪。在这个间隙期间或稳态（闭环）跟踪期间呈现闪光。
在两种情况下，所感知到的闪光位置都沿眼球运动方向发生了偏移。总体误差模式非常相似，间隙条件下的误差大小略小。开环和闭环条件下的误差差异在中央视野最大，在周边最小。
我们根据驱动不同形式眼球运动的神经基质来讨论这些发现。
