Center for Magnetic Resonance Research, University of Minnesota 2021 6th St SE, Minneapolis, MN 55455, United States; Department of Neuroscience, University of Minnesota, 321 Church St SE, Minneapolis, MN 55455.
Center for Magnetic Resonance Research, University of Minnesota 2021 6th St SE, Minneapolis, MN 55455, United States; Department of Neuroscience, University of Minnesota, 321 Church St SE, Minneapolis, MN 55455.
Neuroimage. 2021 Feb 15;227:117654. doi: 10.1016/j.neuroimage.2020.117654. Epub 2020 Dec 15.
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.
大脑组织为独特、灵活的网络。在这些网络中，认知变量（如注意力）可以根据即时的行为需求来调节感官表现。这些调节可以通过改变任务需求来研究；然而，所采用的任务往往与感官系统的假定功能不一致，限制了系统与自然行为的关系的特征描述。在这里，我们结合特定领域的任务操作和超高场 fMRI 来研究自上而下的调节的本质。我们利用了面孔，这是一种由复杂的皮质网络支撑的视觉类别，并在扫描仪中指示参与者执行与刺激相关/特定领域或与刺激无关的任务。我们发现：1. 自上而下的调节中编码了知觉模糊性（即难以形成稳定的感知）；2. 右颞下回在具有挑战性的条件下活跃，并独特地编码了面孔感知的逐次变化。
