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，我们继续关注位置变化对视觉物体识别的影响。人们通常认为，视觉物体识别与视野中的位置无关，我们识别物体的能力不受该物体位置变化的影响。事实上，一些物体识别的模型提出，大脑产生一个抽象的视觉表示的对象，这是独立于其特定的位置或大小，例如，然后可用于与语义或概念知识进行交互。在一系列的行为实验中，我们已经证明，位置上的微小变化确实对物体识别有很大的影响。这些结果表明，视觉系统不包含完全抽象的表征对象。然而，为了证实这些发现，我们现在已经完成了一项功能性磁共振成像（fMRI）研究，以确定位置变化对大脑区域活动的影响，这些区域被认为对物体识别至关重要。与行为结果一致，我们发现，由观看物体引起的活动模式是特定于这些物体呈现的位置的。这些发现为大脑中的物体识别提供了重要的见解，并表明目前的皮质视觉处理模型不能准确反映潜在的机制。 我们还完成了一项研究，调查我们如何识别不同的身体部位（我们自己和他人）。先前的功能性磁共振成像研究已经确定了大脑的一个区域，当人们看到身体部位（例如腿，手臂，脚）时，比看到物体（例如椅子，汽车，锤子）时反应更大。虽然有人认为这个大脑区域可能对我们识别身体的能力很重要，但没有研究表明这个区域包含关于不同身体部位的信息。在一个功能磁共振成像实验中，我们正在研究这个大脑区域的大脑活动，而参与者在视野中的不同位置观看不同身体部位的图像，这些图像来自与他们自己身体或他人身体相对应的视角。我们发现，大脑的这个身体选择区域包含了关于个体身体部位（例如手、手臂）的信息，包括该身体部位在空间中的位置，以及来自身体的哪一侧。这些结果表明，视觉皮层的身体选择区域包含非常具体的身体表征。 阐明大脑如何使我们能够识别物体，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障碍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 continued to focus on the effect of position changes on visual object recognition. It is typically assumed that visual object recognition is independent of position in the visual field, that our ability to recognize an object is unaffected by changes in the position of that object. Indeed, some models of object recognition propose that the brain produces an abstract visual representation of an object that is independent of its specific position or size, for example, which is then available to interact with semantic or conceptual knowledge. In a series of behavioral experiments we have now shown that small changes in position do in fact have a large impact on object recognition. These results suggest that the visual system does not contain completely abstract representations of objects. However, to confirm these findings we have now completed a functional magnetic resonance imaging (fMRI) study to determine the effect of position changes on the activity elicited in regions of the brain thought critical for object recognition. In agreement with the behavioral results, we found that the patterns of activity elicited by viewing objects were specific to the position in which those objects were presented. These findings provide important insights into object recognition in the brain and suggest that current models of cortical visual processing do not accurately reflect the underlying mechanisms. We are also completing a study investigating how we recognize different body parts (our own and others). Previous fMRI studies have identified a region of the brain that responds more when people view body parts (e.g. legs, arms, feet) than when they view objects (e.g. chair, car, hammer). Although it has been suggested that this brain region may be important for our ability to recognize bodies, no study has shown that this region contains information about different body parts. In an fMRI experiment, we are investigating brain activity in this brain region while participants view images of different body parts in different positions in the visual field, taken from perspectives corresponding either to a view of their own body or to a view of someone elses body. We find that this body-selective region of the brain contains information about individual body parts (e.g. hand, arm) including where that body part is in space, and from which side of the body. These results suggest that the body-selective region of the visual cortex contains very specific representations of the body. Elucidating how the brain enables us to recognize objects, 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 disorders.