Object, face and body representations in the human brain

这项研究的目的是了解我们如何看到我们所看到的：大脑如何分析落在眼睛视网膜上的光线，以编码一个充满物体，人和事物的世界？ 在过去的一年里，我们完成了两个项目调查i）视觉心理意象，和ii）场景感知。 i）视觉心理意象。我们的视觉感知是自下而上的感官信息和自上而下的信号之间相互作用的产物，这些信号引导对输入的解释并反映先验知识和意图。在没有感觉输入的情况下，心理意象完全依赖于这种自上而下的信号，并提供了一个研究其对感觉皮层区域影响的机会。使用功能磁共振成像，我们进行了详细的比较视觉图像和知觉的个别复杂的对象。我们发现，（1）我们可以解码参与者在多个大脑区域看到或想象的特定对象的身份，（2）图像和感知信息在整个视觉处理流中的分布不同。这些发现表明，虽然意象和感知涉及相同的大脑区域，但在意象和感知下运行的神经动力学是不同的。 ii）场景感知。现实世界的场景是非常复杂和异构的，但我们能够毫不费力地识别和分类它们。虽然先前的研究已经确定了一个似乎专门用于场景处理的大脑区域，但仍然不清楚这个区域的确切作用是什么。我们向参与者展示了大量复杂的现实世界场景，并使用数据驱动的fMRI方法来识别该区域的表征性质。我们发现，在这个区域中的场景表示主要反映场景的空间属性（例如，无论它们是开放的还是封闭的），而不是语义属性（即场景类别）。 此外，我们已经开始研究复杂视觉场景的不同元素是如何在观看场景时参与的不同大脑区域中表现出来的。具体来说，我们已经创建了由空间背景上的单个对象组成的人工视觉场景，使我们能够将不同大脑区域中表示的空间和对象信息分开。特别是，我们正试图将区域内包含的表示与其解剖连接性联系起来。 阐明大脑如何使我们能够识别物体，场景，面孔和身体，为我们对周围世界的内部表征的本质提供了重要的见解。理解这些表征对于试图确定许多精神健康和神经系统疾病的潜在缺陷至关重要。

The goal of this research is to understand how we see what we see: how does the brain analyze the light falling on the retina of the eye to encode a world full of objects, people and things? During the past year we have completed two projects investigating i) visual mental imagery, and ii) scene perception. i) Visual Mental Imagery. Our visual perception is the product of an interaction between bottom-up sensory information and top-down signals guiding interpretation of the input and reflecting prior knowledge and intent. Mental imagery, in the absence of sensory input, relies entirely on this top-down signal, and provides an opportunity to investigate its impact on sensory cortical areas. Using fMRI we conducted a detailed comparison of visual imagery and perception for individual complex objects. We find that (1) we can decode the identity of the specific object participants view or imagine in multiple brain regions, and (2) imagery and perceptual information are distributed differently throughout the visual processing stream. These findings suggest that while imagery and perception engage the same brain regions, the neural dynamics operating under imagery and perception are different. ii) Scene Perception. Real-world scenes are incredibly complex and heterogeneous, yet we are able to identify and categorize them effortlessly. While prior studies have identified a brain region that appears specialized for scene processing, it remains unclear exactly what the precise role of this region is. We presented participants with large numbers of complex real-world scenes and used a data-driven fMRI approach to identify the nature of representations in this region. We found that scene representations in this region primarily reflect the spatial properties of scenes (e.g. whether they are open or closed) and not the semantic properties (i.e. scene category). Further, we have started to examine how different elements of complex visual scenes are represented across the different brain regions engaged during scene viewing. Specifically, we have created artificial visual scenes comprising a single object on a spatial background, enabling us to tease apart the spatial and object information represented in different brain regions. In particular we are trying to relate the representations contained within regions with their anatomical connectivity. Elucidating how the brain enables us to recognize objects, scenes, faces and bodies provides important insights into the nature of our internal representations of the world around us. Understanding these representations is vital in trying to determine the underlying deficits in many mental health and neurological disorders.