Mazard Angelique, Schiltz Christine, Rossion Bruno
Department of Cognitive Development and Laboratory of Neurophysiology, University of Louvain, Belgium.
Neuropsychologia. 2006;44(6):912-22. doi: 10.1016/j.neuropsychologia.2005.08.015. Epub 2005 Oct 17.
Human faces look more similar to each other when they are presented upside-down, leading to an increase of error rates and response times during individual face discrimination tasks. Here we used functional magnetic resonance imaging (fMRI) to test the hypothesis that this perceived similarity leads to a lower recovery from identity adaptation for inverted faces than for upright faces in face-sensitive areas of the occipito-temporal cortex. Ten subjects were presented with blocks of upright and inverted faces, with the same face identity repeated consecutively in half of the blocks, and different facial identities repeated in the other blocks. When face stimuli were presented upright, the percent signal change in the bilateral middle fusiform gyrus (MFG) was larger for different faces as compared to same faces, replicating previous observations of a recovery from facial identity adaptation in this region. However, there was no significant recovery from adaptation when different inverted faces were presented. Most interestingly, the difference in activation between upright and inverted faces increased progressively during a block when different facial identities were presented. A similar pattern of activation was found in the left middle fusiform gyrus, but was less clear-cut in bilateral face-sensitive areas of the inferior occipital cortex. These findings show that the differential level of activation to upright and inverted faces in the fusiform gyrus is mainly due to a difference in recovery from adaptation, and they explain the discrepancies in the results reported in previous fMRI studies which compared the processing of upright and inverted faces. The lack of recovery from adaptation for inverted faces in the fusiform gyrus may underlie the face inversion effect (FIE), which takes place during perceptual encoding of individual face representations.
当人脸倒置呈现时，它们看起来彼此更相似，这导致在个体面部识别任务中错误率和反应时间增加。在这里，我们使用功能磁共振成像（fMRI）来检验以下假设：在枕颞叶皮质的面部敏感区域，这种感知到的相似性导致倒置面孔的身份适应性恢复低于正立面孔。向10名受试者呈现正立和倒置面孔的组块，在一半的组块中连续重复相同的面部身份，在另一半组块中重复不同的面部身份。当呈现正立面孔刺激时，与相同面孔相比，双侧梭状回中部（MFG）中不同面孔的信号变化百分比更大，这重复了先前在该区域从面部身份适应性恢复的观察结果。然而，当呈现不同的倒置面孔时，没有明显的适应性恢复。最有趣的是，当呈现不同的面部身份时，在一个组块中，正立和倒置面孔之间的激活差异逐渐增加。在左侧梭状回中部发现了类似的激活模式，但在枕叶下部皮质的双侧面部敏感区域不太明显。这些发现表明，梭状回中对正立和倒置面孔的激活差异水平主要是由于适应性恢复的差异，它们解释了先前比较正立和倒置面孔处理的fMRI研究中报告结果的差异。梭状回中倒置面孔缺乏适应性恢复可能是面部倒置效应（FIE）的基础，该效应发生在个体面部表征的感知编码过程中。
