Op de Beeck Hans P, Torfs Katrien, Wagemans Johan
Laboratory of Experimental Psychology, Katholieke Universiteit Leuven, 3000 Leuven, Belgium.
J Neurosci. 2008 Oct 1;28(40):10111-23. doi: 10.1523/JNEUROSCI.2511-08.2008.
Humans rely heavily on shape similarity among objects for object categorization and identification. Studies using functional magnetic resonance imaging (fMRI) have shown that a large region in human occipitotemporal cortex processes the shape of meaningful as well as unfamiliar objects. Here, we investigate whether the functional organization of this region as measured with fMRI is related to perceived shape similarity. We found that unfamiliar object classes that are rated as having a similar shape were associated with a very similar response pattern distributed across object-selective cortex, whereas object classes that were rated as being very different in shape were associated with a more different response pattern. Human observers, as well as object-selective cortex, were very sensitive to differences in shape features of the objects such as straight versus curved versus "spiky" edges, more so than to differences in overall shape envelope. Response patterns in retinotopic areas V1, V2, and V4 were not found to be related to perceived shape. The functional organization in area V3 was partially related to perceived shape but without a stronger sensitivity for shape features relative to overall shape envelope. Thus, for unfamiliar objects, the organization of human object-selective cortex is strongly related to perceived shape, and this shape-based organization emerges gradually throughout the object vision pathway.
人类在对物体进行分类和识别时，严重依赖物体之间的形状相似性。使用功能磁共振成像（fMRI）的研究表明，人类枕颞叶皮层的一个大区域会处理有意义物体以及不熟悉物体的形状。在此，我们研究通过fMRI测量的该区域的功能组织是否与感知到的形状相似性相关。我们发现，被评定为具有相似形状的不熟悉物体类别，与分布在物体选择性皮层上的非常相似的反应模式相关联，而被评定为形状差异很大的物体类别，则与更不同的反应模式相关联。人类观察者以及物体选择性皮层，对物体形状特征的差异（如直边与曲边与“尖刺”边）非常敏感，比对整体形状轮廓的差异更敏感。在视网膜拓扑区域V1、V2和V4中的反应模式未被发现与感知到的形状相关。V3区域的功能组织部分与感知到的形状相关，但相对于整体形状轮廓，对形状特征没有更强的敏感性。因此，对于不熟悉的物体，人类物体选择性皮层的组织与感知到的形状密切相关，并且这种基于形状的组织在整个物体视觉通路中逐渐形成。
