Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, 3010 Victoria, Australia
J Neurosci. 2020 Jul 22;40(30):5698-5705. doi: 10.1523/JNEUROSCI.0275-20.2020.
Because of the delays inherent in neural transmission, the brain needs time to process incoming visual information. If these delays were not somehow compensated, we would consistently mislocalize moving objects behind their physical positions. Twenty-five years ago, Nijhawan used a perceptual illusion he called the flash-lag effect (FLE) to argue that the brain's visual system solves this computational challenge by extrapolating the position of moving objects (Nijhawan, 1994). Although motion extrapolation had been proposed a decade earlier (e.g., Finke et al., 1986), the proposal that it caused the FLE and functioned to compensate for computational delays was hotly debated in the years that followed, with several alternative interpretations put forth to explain the effect. Here, I argue, 25 years later, that evidence from behavioral, computational, and particularly recent functional neuroimaging studies converges to support the existence of motion extrapolation mechanisms in the visual system, as well as their causal involvement in the FLE. First, findings that were initially argued to challenge the motion extrapolation model of the FLE have since been explained, and those explanations have been tested and corroborated by more recent findings. Second, motion extrapolation explains the spatial shifts observed in several FLE conditions that cannot be explained by alternative (temporal) models of the FLE. Finally, neural mechanisms that actually perform motion extrapolation have been identified at multiple levels of the visual system, in multiple species, and with multiple different methods. I outline key questions that remain, and discuss possible directions for future research.
由于神经传递的延迟，大脑需要时间来处理输入的视觉信息。如果这些延迟没有得到某种补偿，我们将始终错误地将移动的物体定位在其实际位置的后面。二十五年前，Nijhawan 使用了一种他称之为闪光滞后效应（FLE）的感知错觉，来论证大脑的视觉系统通过外推移动物体的位置来解决这个计算挑战（Nijhawan，1994）。尽管运动外推早在十年前就已经提出（例如，Finke 等人，1986），但随后的几年里，关于运动外推导致 FLE 并起到补偿计算延迟作用的提议引起了激烈的争论，提出了几种替代解释来解释这种效应。在这里，我认为，25 年后，来自行为、计算，特别是最近的功能神经影像学研究的证据汇聚在一起，支持视觉系统中存在运动外推机制，以及它们在 FLE 中的因果关系。首先，最初被认为挑战 FLE 运动外推模型的发现，此后得到了解释，这些解释已经通过最近的发现得到了测试和证实。其次，运动外推解释了在几种 FLE 条件下观察到的空间移位，而这些移位无法用 FLE 的替代（时间）模型来解释。最后，在多个物种中，通过多种不同的方法，在视觉系统的多个层次上已经确定了实际执行运动外推的神经机制。我概述了仍然存在的关键问题，并讨论了未来研究的可能方向。
