Kriegeskorte Nikolaus, Sorger Bettina, Naumer Marcus, Schwarzbach Jens, van den Boogert Erik, Hussy Walter, Goebel Rainer
Department of Cognitive Neuroscience, Faculty of Psychology, Universiteit Maastricht, 6229 ER Maastricht, The Netherlands.
J Neurosci. 2003 Feb 15;23(4):1451-63. doi: 10.1523/JNEUROSCI.23-04-01451.2003.
Moving dots can evoke a percept of the spatial structure of a three-dimensional object in the absence of other visual cues. This phenomenon, called structure from motion (SFM), suggests that the motion flowfield represented in the dorsal stream can form the basis of object recognition performed in the ventral stream. SFM processing is likely to contribute to object perception whenever there is relative motion between the observer and the object viewed. Here we investigate the motion flowfield component of object recognition with functional magnetic resonance imaging. Our SFM stimuli encoded face surfaces and random three-dimensional control shapes with matched curvature properties. We used two different types of an SFM stimulus with the dots either fixed to the surface of the object or moving on it. Despite the radically different encoding of surface structure in the two types of SFM, both elicited strong surface percepts and involved the same network of cortical regions. From early visual areas, this network extends dorsally into the human motion complex and parietal regions and ventrally into object-related cortex. The SFM stimuli elicited a face-selective response in the fusiform face area. The human motion complex appears to have a central role in SFM object recognition, not merely representing the motion flowfield but also the surface structure of the motion-defined object. The motion complex and a region in the intraparietal sulcus reflected the motion state of the SFM-implicit object, responding more strongly when the implicit object was in motion than when it was stationary.
在没有其他视觉线索的情况下，移动的点可以唤起对三维物体空间结构的感知。这种现象被称为运动视差结构（SFM），表明背侧流中所代表的运动流场可以构成腹侧流中物体识别的基础。只要观察者与所观察物体之间存在相对运动，SFM处理就可能有助于物体感知。在这里，我们使用功能磁共振成像来研究物体识别中的运动流场成分。我们的SFM刺激编码了面部表面和具有匹配曲率特性的随机三维控制形状。我们使用了两种不同类型的SFM刺激，其中点要么固定在物体表面，要么在物体表面上移动。尽管两种类型的SFM在表面结构编码上有根本差异，但两者都引发了强烈的表面感知，并且涉及相同的皮质区域网络。从早期视觉区域开始，这个网络背侧延伸到人类运动复合体和顶叶区域，腹侧延伸到与物体相关的皮质。SFM刺激在梭状面孔区引发了面孔选择性反应。人类运动复合体似乎在SFM物体识别中起核心作用，不仅代表运动流场，还代表运动定义物体的表面结构。运动复合体和顶内沟中的一个区域反映了SFM隐含物体的运动状态，当隐含物体运动时比静止时反应更强烈。
