The brain is organized into distinct, flexible networks. Within these networks, cognitive variables such as attention can modulate sensory representations in accordance with moment-to-moment behavioral requirements. These modulations can be studied by varying task demands; however, the tasks employed are often incongruent with the postulated functions of a sensory system, limiting the characterization of the system in relation to natural behaviors. Here we combine domain-specific task manipulations and ultra-high field fMRI to study the nature of top-down modulations. We exploited faces, a visual category underpinned by a complex cortical network, and instructed participants to perform either a stimulus-relevant/domain-specific or a stimulus-irrelevant task in the scanner. We found that 1. perceptual ambiguity (i.e. difficulty of achieving a stable percept) is encoded in top-down modulations from higher-level cortices; 2. the right inferior-temporal lobe is active under challenging conditions and uniquely encodes trial-by-trial variability in face perception.

中文翻译：

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使用超高场fMRI阐明高级皮质在解决知觉歧义中的作用

大脑组织成不同的，灵活的网络。在这些网络中，诸如注意力之类的认知变量可以根据时刻对行为的要求来调节感觉表现。可以通过改变任务需求来研究这些调制。然而，所采用的任务通常与感觉系统的假定功能不一致，从而限制了系统与自然行为有关的特征。在这里，我们结合特定领域的任务操纵和超高场功能磁共振成像来研究自顶向下调制的性质。我们利用人脸这一复杂的皮质网络所支撑的视觉类别，并指示参与者在扫描仪中执行与刺激有关/特定领域或与刺激无关的任务。我们发现1.感知歧义（即 难以实现稳定的感知）是由高层皮质以自顶向下的方式编码的；2.右下颞叶在挑战性条件下活跃，并且独特地编码了面部感知的逐次试验变异性。