Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen 6500 HB, The Netherlands, University of Birmingham, School of Psychology, Birmingham B15 2TT, West Midlands, United Kingdom, and Departments of Physiology and Pharmacology, Psychology, and Robarts Research Institute, Western University, London, Ontario N6A 5B7, Canada.
J Neurosci. 2014 Apr 16;34(16):5497-504. doi: 10.1523/JNEUROSCI.4773-13.2014.
Every saccadic eye movement that we make changes the image of the world on our retina. Yet, despite these retinal shifts, we still perceive our visual world to be stable. Efference copy from the oculomotor system to the visual system has been suggested to contribute to this stable percept, enabling the brain to anticipate the retinal image shifts by remapping the neural image. A psychophysical phenomenon that has been linked to this predictive remapping is the mislocalization of a stimulus flashed around the time of a saccade. If this mislocalization is initiated by saccade preparation, one should also observe localization errors when a saccade is planned, but abruptly aborted just before its execution. We tested this hypothesis in human subjects using a novel paradigm that combines a flash localization task with a countermanding component that occasionally requires saccade cancellation. Surprisingly, we found no trace of mislocalization, even for saccades cancelled close to the point of no return. This strongly suggests that the actual execution of the saccade is a prerequisite for the typical localization errors, which rejects various models and constrains neural substrates. We conclude that perisaccadic mislocalization is not a direct consequence of saccade preparation, but arises after saccade execution when the flash location is constructed from memory.
我们每进行一次扫视眼动，都会使视网膜上的世界图像发生变化。然而，尽管这些视网膜位移，我们仍然能感觉到我们的视觉世界是稳定的。来自眼球运动系统到视觉系统的传出副本被认为有助于这种稳定的感知，使大脑能够通过重新映射神经图像来预测视网膜图像的位移。与这种预测性重映射相关的一种心理物理学现象是刺激在扫视时周围闪烁时的误定位。如果这种误定位是由扫视准备引发的，那么在计划扫视但在其执行之前突然中止时，也应该观察到定位错误。我们在人类受试者中使用一种新的范式来测试这个假设，该范式结合了闪光定位任务和一个反抑制成分，该成分偶尔需要扫视取消。令人惊讶的是，即使是在接近不可挽回点时取消的扫视，我们也没有发现任何误定位的痕迹。这强烈表明，扫视的实际执行是典型定位错误的前提，这拒绝了各种模型并限制了神经基质。我们得出结论，扫视周围的误定位不是扫视准备的直接结果，而是在扫视执行后，当从记忆中构建闪光位置时出现的。
