Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Neuroimage. 2010 Apr 1;50(2):383-95. doi: 10.1016/j.neuroimage.2009.12.077. Epub 2009 Dec 28.
Using an fMR-adaptation paradigm for different face morphing levels we have recently demonstrated a narrow neuronal tuning to faces even at the sub-exemplar level which was tightly related to perceptual discrimination (Gilaie-Dotan and Malach, 2007). However, it is unclear whether this relationship is unique to faces or is a general property of object representations including unfamiliar objects, and whether the adaptation tuning is due to physical changes in the stimulus or to changes in perceptual discrimination. Here we compared the same face-morph paradigm for upright and inverted faces, thus modulating familiarity and perceptual discrimination effects while equating all low-level features. We found, as expected, a perceptual "inversion effect", i.e. a significant reduction in inverted face discrimination. Importantly, the fMR-adaptation tuning in the fusiform face area (FFA) changed in accordance with the different perceptual sensitivity both for upright and inverted faces. Additional object selective regions displayed differential tuning widths to the two categories. Our results are compatible with a model by which the ability of human observers to discriminate objects depends on the shape tuning properties of individual neurons.
利用不同面孔变形水平的 fMRI 适应范式，我们最近证明了即使在亚范例水平，神经元对面孔也有狭窄的调谐，这种调谐与知觉辨别紧密相关（Gilaie-Dotan 和 Malach，2007）。然而，目前尚不清楚这种关系是否是面孔所特有的，还是包括不熟悉物体在内的物体表示的一般属性，以及适应调谐是否是由于刺激的物理变化还是由于知觉辨别力的变化所致。在这里，我们比较了相同的面孔变形范式用于直立和倒置的面孔，从而调节熟悉度和知觉辨别效果，同时使所有低水平特征保持一致。正如预期的那样，我们发现了一种知觉的“反转效应”，即倒置面孔的辨别力显著降低。重要的是，梭状回面孔区（FFA）中的 fMRI 适应调谐与直立和倒置面孔的不同知觉敏感性相符。其他的物体选择性区域对两个类别显示出不同的调谐宽度。我们的结果与这样一种模型是一致的，即人类观察者辨别物体的能力取决于单个神经元的形状调谐特性。
