Visual perception is introspectively stable and continuous across eye movements. It has been hypothesized that displacements in retinal input caused by eye movements can be dissociated from displacements in the external world using extra-retinal information, such as a corollary discharge from the oculomotor system. The extra-retinal information can inform the visual system about an upcoming eye movement and accompanying displacements in retinal input. The parietal cortex has been hypothesized to be critically involved in integrating retinal and extra-retinal information. Two tasks have been widely used to assess the quality of this integration: double-step saccades and intra-saccadic displacements. Double-step saccades performed by patients with parietal cortex lesions seemed to show hypometric second saccades. However, recently idea has been refuted by demonstrating that patients with very similar lesions were able to perform the double step saccades, albeit taking multiple saccades to reach the saccade target. So, it seems that extra-retinal information is still available for saccade execution after a lesion to the parietal lobe. Here, we investigated whether extra-retinal signals are also available for perceptual judgements in nine patients with strokes affecting the posterior parietal cortex. We assessed perceptual continuity with the intra-saccadic displacement task. We exploited the increased sensitivity when a small temporal blank is introduced after saccade offset (blank effect). The blank effect is thought to reflect the availability of extra-retinal signals for perceptual judgements. Although patients exhibited a relative difference to control subjects, they still demonstrated the blank effect. The data suggest that a lesion to the posterior parietal cortex (PPC) alters the processing of extra-retinal signals but does not abolish their influence altogether.

中文翻译：

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病灶对顶叶后皮质的囊内位移敏感性。

视觉感知自发地稳定且在整个眼球运动中连续不断。假设使用眼外运动信息，例如动眼系统的必然放电，可以将由眼球运动引起的视网膜输入位移与外部世界的位移分离开。视网膜外信息可以通知视觉系统即将发生的眼球运动以及随之而来的视网膜输入位移。假设顶叶皮层参与整合视网膜和视网膜外信息至关重要。两项任务已被广泛用于评估这种整合的质量：双步扫视和眼内位移。顶叶皮层病变患者进行的双步扫视似乎显示了低估的第二扫视。然而，最近的观点通过证明具有非常相似的病变的患者能够执行双步扫视（尽管采取了多个扫视以达到扫视目标）而被驳斥。因此，似乎在损伤顶叶后仍可以进行眼底扫视的视网膜外信息。在这里，我们调查了9名中风影响后顶叶皮层的患者是否还可以通过视网膜外信号进行知觉判断。我们评估了声调内置换任务的知觉连续性。当扫视偏移（空白效应）后引入一个小的时间空白时，我们利用了增加的灵敏度。空白效应被认为反映了视网膜外信号在知觉判断中的可用性。尽管患者与对照组相比有相对差异，他们仍然表现出了空白效果。数据表明，顶叶后皮质（PPC）的病变改变了视网膜外信号的处理，但并未完全消除其影响。