Section on Learning and Plasticity, Laboratory of Brain and Cognition, National Institute of Mental Health/National Institutes of Health , Bethesda, Maryland 20892.
Department of Psychology, The George Washington University , Washington, DC 20052.
eNeuro. 2016 Sep 27;3(5). doi: 10.1523/ENEURO.0139-16.2016. eCollection 2016 Sep-Oct.
Our remarkable ability to process complex visual scenes is supported by a network of scene-selective cortical regions. Despite growing knowledge about the scene representation in these regions, much less is known about the temporal dynamics with which these representations emerge. We conducted two experiments aimed at identifying and characterizing the earliest markers of scene-specific processing. In the first experiment, human participants viewed images of scenes, faces, and everyday objects while event-related potentials (ERPs) were recorded. We found that the first ERP component to evince a significantly stronger response to scenes than the other categories was the P2, peaking ∼220 ms after stimulus onset. To establish that the P2 component reflects scene-specific processing, in the second experiment, we recorded ERPs while the participants viewed diverse real-world scenes spanning the following three global scene properties: spatial expanse (open/closed), relative distance (near/far), and naturalness (man-made/natural). We found that P2 amplitude was sensitive to these scene properties at both the categorical level, distinguishing between open and closed natural scenes, as well as at the single-image level, reflecting both computationally derived scene statistics and behavioral ratings of naturalness and spatial expanse. Together, these results establish the P2 as an ERP marker for scene processing, and demonstrate that scene-specific global information is available in the neural response as early as 220 ms.
我们处理复杂视觉场景的非凡能力是由一组场景选择的皮质区域网络支持的。尽管关于这些区域的场景表示的知识不断增加，但对于这些表示是如何出现的时间动态却知之甚少。我们进行了两项实验，旨在确定和描述场景特定处理的最早标记。在第一项实验中，人类参与者观看了场景、面孔和日常物体的图像，同时记录了事件相关电位（ERP）。我们发现，第一个表现出比其他类别对场景更强反应的 ERP 成分是 P2，在刺激出现后约 220 毫秒达到峰值。为了确定 P2 成分反映了场景特定的处理，在第二项实验中，当参与者观看跨越以下三个全局场景属性的各种真实场景时，我们记录了 ERPs：空间范围（开/关）、相对距离（近/远）和自然性（人造/自然）。我们发现，P2 幅度在类别水平上对这些场景属性敏感，区分开/关自然场景，以及在单个图像水平上敏感，反映了计算得出的场景统计数据和自然性和空间范围的行为评分。总之，这些结果确立了 P2 作为场景处理的 ERP 标记，并表明场景特定的全局信息早在 220 毫秒就可在神经反应中获得。
