Rossion Bruno, Joyce Carrie A, Cottrell Garrison W, Tarr Michael J
Cognitive Neuroscience Unit, University of Louvain, Belgium.
Neuroimage. 2003 Nov;20(3):1609-24. doi: 10.1016/j.neuroimage.2003.07.010.
Event-related potential (ERP) studies of the human brain have shown that object categories can be reliably distinguished as early as 130-170 ms on the surface of occipito-temporal cortex, peaking at the level of the N170 component. Consistent with this finding, neuropsychological and neuroimaging studies suggest major functional distinctions within the human object recognition system, particularly in hemispheric advantage, between the processing of words (left), faces (right), and objects (bilateral). Given these observations, our aim was to (1) characterize the differential response properties of the N170 to pictures of faces, objects, and words across hemispheres; and (2) test whether an effect of inversion for highly familiar and monooriented nonface stimuli such as printed words can be observed at the level of the N170. Scalp EEG (53 channels) was recorded in 15 subjects performing an orientation decision task with pictures of faces, words, and cars presented upright or inverted. All three categories elicited at the same latency a robust N170 component associated with a positive counterpart at centro-frontal sites (vertex-positive potential, VPP). While there were minor amplitude differences at the level of the occipital medial P1 between linguistic and nonlinguistic categories, scalp topographies and source analyses indicated strong hemispheric and orientation effects starting at the level of the N170, which was right lateralized for faces, smaller and bilateral for cars, and as large for printed words in the left hemisphere as for faces. The entire N170/VPP complex was accounted for by two dipolar sources located in the lateral inferior occipital cortex/posterior fusiform gyrus. These two locations were roughly equivalent across conditions but differed in strength and lateralization. Inversion delayed the N170 (and VPP) response for all categories, with an increasing delay for cars, words, and faces, respectively, as suggested by source modeling analysis. Such results show that early processes in object recognition respond to category-specific visual information, and are associated with strong lateralization and orientation bias.
对人类大脑的事件相关电位（ERP）研究表明，早在枕颞叶皮质表面130 - 170毫秒时就能可靠地区分物体类别，在N170成分水平达到峰值。与这一发现一致的是，神经心理学和神经影像学研究表明，人类物体识别系统内存在主要的功能差异，特别是在半球优势方面，在单词（左半球）、面孔（右半球）和物体（双侧）的处理之间。基于这些观察结果，我们的目标是：（1）描述N170对跨半球的面孔、物体和单词图片的差异反应特性；（2）测试对于高度熟悉且单方向的非面孔刺激（如印刷单词），是否能在N170水平观察到倒置效应。对15名受试者进行头皮脑电图（53个通道）记录，他们执行一项方向判断任务，任务中呈现正立或倒置的面孔、单词和汽车图片。所有这三类刺激在相同潜伏期都引发了一个强大的N170成分，同时在中央额叶部位伴有一个正性对应成分（顶点正电位，VPP）。虽然在枕叶内侧P1水平，语言和非语言类别之间存在微小的幅度差异，但头皮地形图和源分析表明，从N170水平开始就存在强烈的半球和方向效应，面孔的N170在右侧半球更明显，汽车的N170较小且双侧分布，印刷单词在左半球的N170与面孔的一样大。整个N170/VPP复合体由位于枕叶下外侧皮质/梭状回后部的两个偶极源解释。这两个位置在不同条件下大致相当，但在强度和定位上有所不同。源模型分析表明，倒置会延迟所有类别的N170（和VPP）反应，汽车、单词和面孔的延迟分别增加。这些结果表明，物体识别的早期过程对特定类别的视觉信息有反应，并与强烈的定位和方向偏差相关。
