Relatively little is known about visual processing during free-viewing visual search in realistic dynamic environments. Free-viewing is characterized by frequent saccades. During saccades, visual processing is thought to be suppressed, yet we know that the presaccadic visual content can modulate postsaccadic processing. To better understand these processes in a realistic setting, we study here saccades and neural responses elicited by the appearance of visual targets in a realistic virtual environment. While subjects were being driven through a 3D virtual town, they were asked to discriminate between targets that appear on the road. Using a system identification approach, we separated overlapping and correlated activity evoked by visual targets, saccades, and button presses. We found that the presence of a target enhances early occipital as well as late frontocentral saccade-related responses. The earlier potential, shortly after 125 ms post-saccade onset, was enhanced for targets that appeared in the peripheral vision as compared to the central vision, suggesting that fast peripheral processing initiated before saccade onset. The later potential, at 195 ms post-saccade onset, was strongly modulated by the visibility of the target. Together these results suggest that, during natural viewing, neural processing of the presaccadic visual stimulus continues throughout the saccade, apparently unencumbered by saccadic suppression.

中文翻译：

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在自然观察期间，视觉目标的神经处理在整个扫视过程中持续进行。

在现实动态环境中的自由查看视觉搜索过程中，对视觉处理知之甚少。自由观看的特点是频繁的扫视。在扫视期间，视觉处理被认为受到抑制，但我们知道扫视前的视觉内容可以调节扫视后的处理。为了在现实环境中更好地理解这些过程，我们在这里研究了由现实虚拟环境中视觉目标的出现引起的眼跳和神经反应。当受试者被驱动通过一个 3D 虚拟城镇时，他们被要求区分道路上出现的目标。使用系统识别方法，我们将视觉目标、扫视和按钮按下引起的重叠和相关活动分开。我们发现目标的存在增强了早期枕叶以及晚期额中央扫视相关的反应。较早的电位，即在跳视后 125 毫秒后不久，与中央视觉相比，出现在周边视觉中的目标增强了，这表明在跳视开始之前启动了快速的周边处理。后来的电位，在 195 ms 后跳视开始时，受到目标可见性的强烈调节。这些结果一起表明，在自然观看期间，对扫视前视觉刺激的神经处理在整个扫视过程中持续进行，显然不受扫视抑制的阻碍。与中央视觉相比，周边视觉中出现的目标增强了，这表明快速周边处理在跳视开始之前启动。后来的电位，在 195 ms 后跳视开始时，受到目标可见性的强烈调节。这些结果一起表明，在自然观看期间，对扫视前视觉刺激的神经处理在整个扫视过程中持续进行，显然不受扫视抑制的阻碍。与中央视觉相比，周边视觉中出现的目标增强了，这表明快速周边处理在跳视开始之前启动。后来的电位，在 195 ms 后跳视开始时，受到目标可见性的强烈调节。这些结果一起表明，在自然观看期间，对扫视前视觉刺激的神经处理在整个扫视过程中持续进行，显然不受扫视抑制的阻碍。