Ouerfelli-Ethier Julie, Salemme Romeo, Fournet Romain, Urquizar Christian, Pisella Laure, Khan Aarlenne Z
School of Optometry, University of Montreal, Montreal H3T 1P1, Canada.
Lyon Neuroscience Research Center, Trajectoires Team, INSERM 1028, CNRS UMR 5292, University of Lyon I Claude-Bernard, Lyon 69500, France.
Cereb Cortex Commun. 2021 Sep 13;2(3):tgab054. doi: 10.1093/texcom/tgab054. eCollection 2021.
Anti-saccades are eye movements that require inhibition to stop the automatic saccade to the visual target and to perform instead a saccade in the opposite direction. The inhibitory processes underlying anti-saccades have been primarily associated with frontal cortex areas for their role in executive control. Impaired performance in anti-saccades has also been associated with the parietal cortex, but its role in inhibitory processes remains unclear. Here, we tested the assumption that the dorsal parietal cortex contributes to spatial inhibition processes of contralateral visual target. We measured anti-saccade performance in 2 unilateral optic ataxia patients and 15 age-matched controls. Participants performed 90 degree (across and within visual fields) and 180 degree inversion anti-saccades, as well as pro-saccades. The main result was that our patients took longer to inhibit visually guided saccades when the visual target was presented in the ataxic hemifield and the task required a saccade across hemifields. This was observed through anti-saccades latencies and error rates. These deficits show the crucial role of the dorsal posterior parietal cortex in spatial inhibition of contralateral visual target representations to plan an accurate anti-saccade toward the ipsilesional side.
反扫视是一种眼球运动，需要抑制才能阻止自动向视觉目标的扫视，并改为向相反方向进行扫视。反扫视背后的抑制过程主要与额叶皮质区域有关，因为它们在执行控制中发挥作用。反扫视表现受损也与顶叶皮质有关，但其在抑制过程中的作用仍不清楚。在这里，我们测试了背侧顶叶皮质有助于对侧视觉目标的空间抑制过程这一假设。我们测量了2名单侧视觉性共济失调患者和15名年龄匹配的对照组的反扫视表现。参与者进行了90度（跨视野和在视野内）和180度反转的反扫视以及顺向扫视。主要结果是，当视觉目标出现在共济失调半视野且任务需要跨半视野扫视时，我们的患者抑制视觉引导扫视的时间更长。这通过反扫视潜伏期和错误率得以观察到。这些缺陷表明背侧后顶叶皮质在对侧视觉目标表征的空间抑制中起着关键作用，以便向同侧计划准确的反扫视。
