Neural representation of scene context during visual search

描述（由申请人提供）：预测目标位置的合成线索（例如，箭头和框）加快了搜索时间，并提高了决策准确性。同样，当观察者在自然场景中搜索时，一个高度可见的物体（如房屋）经常与寻找的目标（如烟囱）同时出现在自然环境中，当目标出现在物体附近时，它会影响眼球运动，并促进搜索。虽然在过去的几十年里，单细胞神经生理学、人体电生理学和神经成像在理解注意力和合成线索对神经活动的影响方面取得了巨大进展，但人们对真实场景中视觉搜索过程中介导情境效应的潜在神经机制知之甚少。在此，我们建议使用功能磁共振成像（fMRI）单独测量观察者在真实场景中搜索目标时的神经活动，并使用神经解码方法（多变量模式分析）和一种新的群体感受野方法：1)确定代表场景上下文空间位置的大脑区域（fMRI），从而可能介导真实场景中搜索的指导；2)评估场景上下文编码是自动的还是由自上而下的视觉注意调制的。本文提出的工作将提高我们对场景上下文的神经机制的理解，这可以说是观察者在自然环境中优化视觉搜索的最重要策略之一。我们的研究结果也将促进我们对与注意力、物体/场景和视觉搜索的上下文关联相关的大脑区域的功能和作用的理解。这些进展可能有助于识别低视力和注意力缺陷患者在现实场景中的视觉搜索等重要生态任务中不良行为表现的神经关联。

DESCRIPTION (provided by applicant): Synthetic cues (e.g., arrows and boxes) predictive of a target location speed up search times and result in increased decision accuracy. Similarly, when observers search in natural scenes, a highly visible object (e.g., house) that often co-occurs in natural environments with a sought target (e.g., chimney) will influence eye movements and facilitate search when the target appears close to the object. While the last few decades have seen single cell neurophysiology, human electrophysiology and neuroimaging lead to great advances in the understanding of the effects of attention and synthetic cues on neural activity, little is known about the underlying neural mechanisms mediating context effects during visual search in real scenes. Here, we propose to separately measure neural activity using functional magnetic resonance imaging (fMRI) while observers search for targets in real scenes and use neural decoding methods (multivariate pattern analysis) and a novel variation of population receptive field methods to: 1) Determine the brain areas (fMRI) that represent the spatial location of scene context and thus might mediate guidance of search in real scenes; 2) To evaluate whether the coding of scene context is automatic or whether it is modulated by top-down visual attention. The proposed work will improve our understanding of the neural mechanisms of scene context which arguably is one of the most important strategies used by observers to optimize visual search in natural environments. Our results will also advance our understanding of the function and role of brain regions related to attention, objects/scenes, and contextual associations for visual search. These advances might potentially help in identifying neural correlates of poor behavioral performance for patients with low-vision and attentional deficits in an ecologically important task such as visual search in real scenes.