Department of Biomedical Engineering, Technion-Israel Institute of Technology Haifa, Israel.
J Vis. 2024 Oct 3;24(11):11. doi: 10.1167/jov.24.11.11.
When we view the world, our eyes saccade quickly between points of interest. Even when fixating a target our eyes are not completely at rest but execute small fixational eye movements (FEMs). That vision is not blurred despite this ever-present jitter has seemingly motivated an increasingly popular theory denying the reliance of the visual system on pure spatial processing in favor of a space-to-time mechanism generated by the eye drifting across the image. Accordingly, FEMs are not detrimental but rather essential to good visibility. However, the space-to-time theory is incompatible with physiological data showing that all information is conveyed by the short neural volleys generated when the eyes land on a target, and with our faithful perception of briefly displayed objects, during which time FEMs have no effect. Another difficulty in rejecting the idea of image representation by the locations and nature of responding cells in favor of a timecode, is that somewhere, somehow, this code must be decoded into a parallel spatial one when reaching perception. Thus, in addition to the implausibility of generating meaningful responses during retinal drift, the space-to-time hypothesis calls for replacing efficient point-to-point parallel transmission with a cumbersome, delayed, space-to-time-to-space process. A novel physiological framework is presented here wherein the ability of the visual system to quickly process information is mediated by the short, powerful neural volleys generated by the landing saccades. These volleys are necessary and sufficient for normal perception without FEMs contribution. This mechanism enables our excellent perception of brief stimuli and explains that visibility is not blurred by FEMs because they do not generate useful information.
当我们观察世界时，眼睛会快速扫视感兴趣的点。即使在注视目标时，眼睛也不完全静止，而是会执行微小的眼跳（fixational eye movements，FEMs）。尽管存在这种持续的抖动，但视觉并没有变得模糊，这似乎激发了一种越来越流行的理论，该理论否认视觉系统依赖于纯粹的空间处理，而赞成由眼睛在图像上漂移产生的空间到时间的机制。因此，FEMs 不仅不是有害的，而且对于良好的能见度是必不可少的。然而，空间到时间的理论与生理数据不兼容，这些数据表明，所有信息都是由眼睛落在目标上时产生的短暂神经冲动传递的，并且我们可以忠实地感知短暂显示的物体，在此期间 FEMs 没有影响。另一个困难是，拒绝以响应细胞的位置和性质来表示图像的想法，转而支持时间码，因为在某个地方，以某种方式，当到达感知时，这个代码必须被解码成一个并行的空间码。因此，除了在视网膜漂移期间产生有意义的反应的不可能性之外，空间到时间的假设还要求用一种繁琐、延迟的空间到时间到空间的过程来取代高效的点对点并行传输。本文提出了一种新的生理框架，其中视觉系统快速处理信息的能力是由着陆扫视产生的短暂而强大的神经冲动介导的。这些冲动对于正常感知是必要且充分的，而不需要 FEMs 的贡献。这种机制使我们能够很好地感知短暂的刺激，并解释了 FEMs 不会使视觉变得模糊，因为它们不会产生有用的信息。
