Neural and Behavioral Analyses of the Representation of Shape

在几分之一秒的时间内，人类观察者可以很容易地理解以前从未遇到过的物体或场景的图像。对这种非凡能力的神经基础的了解，是通过发现一个皮质区域，该区域是由完整物体的形状激活的，而不是由这些相同图像的混乱版本激活的。这一大脑区域被称为枕侧复合体(LOC)，在功能磁共振成像(FMRI)研究中被熟悉和陌生的物体激活。LOC也被同一对象的照片和线条图激活，表明表面质量在其他地方表现出来。而且，双侧病变到LOC已被证明导致完全不能根据物体的形状识别物体。因此，LoC表示物理形状，推测包括名称在内的语义信息可以关联到该物理形状。在国家科学基金会的支持下，南加州大学的欧文·比德曼博士和他的同事们将进行一系列实验，旨在更好地确定形状在LOC中的表现方式。其中一个项目将测试部件和关系是否有可区分的神经轨迹。其他项目将评估LOC中的形状编码是否根据局部图像特征、部分、全局形状或概念来完成，以及形状的不变编码在LOC中的表现位置和程度--即使在视野中的不同位置、不同大小、不同方向或从不同方向照明时，也可以识别为不变的对象。这项研究将填补人类在物体识别方面的心理物理学研究和在非人类灵长类动物中进行的反应形状变化的单神经元记录工作之间的一个关键空白。虽然人类和非人灵长类动物初级感觉和运动皮质之间的同源已经被很好地建立起来，但关于后来的知觉关联区的同源仍然存在重大问题。也许这项拟议的研究最重要的潜在影响是，它可以让我们理解神经表征，这些表征不仅有助于物体识别，而且有助于更广泛的认知。

In a fraction of a second a human observer can easily comprehend an image of an object or scene that has never been encountered before. Knowledge of the neural basis of this remarkable ability has been advanced by the discovery of a cortical area that is activated by the shape of intact objects but not by scrambled versions of these same images. This brain region, termed the lateral occipital complex (LOC), is activated in functional magnetic resonance imaging (fMRI) studies by both familiar and unfamiliar objects. The LOC is also activated by both photographs and line drawings of the same object, indicating that the surface qualities are represented elsewhere. And, bilateral lesions to LOC have been shown to produce a complete inability to recognize objects on the basis of their shape. LOC thus represents physical shape to which, presumably, semantic information, including a name, can be associated. With support from the National Science Foundation, Dr. Irving Biederman and colleagues at the University of Southern California will conduct a series of experiments that aim to better determine how shape is represented in the LOC. One project will test whether parts and relations have distinguishable neural loci. Other projects will assess whether the coding of shape in the LOC is accomplished in terms of local image features, parts, global shape or concepts, and the locus and extent to which invariant coding of shape - which allows an object to be recognized as unchanged even when it is viewed at a different position in the visual field, at a different size, at a different orientation, or lit from a different direction - is manifested in LOC. This research will fill a critical gap between human psychophysical research on object recognition and work on single-neuron recordings in response shape variations that have been performed in non-human primates. Although the homologues between human and non-human primate primary sensory and motor cortices are well established there are significant questions concerning the homologues of later, perceptual association areas. Perhaps the most important potential impact of the proposed research is that it could allow us to understand the neural representations that subserve not only object recognition but cognition more generally.