Malach R, Reppas J B, Benson R R, Kwong K K, Jiang H, Kennedy W A, Ledden P J, Brady T J, Rosen B R, Tootell R B
Massachusetts General Hospital-Nuclear Magnetic Resonance Center, Department of Radiology, Boston 02114, USA.
Proc Natl Acad Sci U S A. 1995 Aug 29;92(18):8135-9. doi: 10.1073/pnas.92.18.8135.
The stages of integration leading from local feature analysis to object recognition were explored in human visual cortex by using the technique of functional magnetic resonance imaging. Here we report evidence for object-related activation. Such activation was located at the lateral-posterior aspect of the occipital lobe, just abutting the posterior aspect of the motion-sensitive area MT/V5, in a region termed the lateral occipital complex (LO). LO showed preferential activation to images of objects, compared to a wide range of texture patterns. This activation was not caused by a global difference in the Fourier spatial frequency content of objects versus texture images, since object images produced enhanced LO activation compared to textures matched in power spectra but randomized in phase. The preferential activation to objects also could not be explained by different patterns of eye movements: similar levels of activation were observed when subjects fixated on the objects and when they scanned the objects with their eyes. Additional manipulations such as spatial frequency filtering and a 4-fold change in visual size did not affect LO activation. These results suggest that the enhanced responses to objects were not a manifestation of low-level visual processing. A striking demonstration that activity in LO is uniquely correlated to object detectability was produced by the "Lincoln" illusion, in which blurring of objects digitized into large blocks paradoxically increases their recognizability. Such blurring led to significant enhancement of LO activation. Despite the preferential activation to objects, LO did not seem to be involved in the final, "semantic," stages of the recognition process. Thus, objects varying widely in their recognizability (e.g., famous faces, common objects, and unfamiliar three-dimensional abstract sculptures) activated it to a similar degree. These results are thus evidence for an intermediate link in the chain of processing stages leading to object recognition in human visual cortex.
通过功能磁共振成像技术，在人类视觉皮层中探索了从局部特征分析到物体识别的整合阶段。在此我们报告与物体相关的激活证据。这种激活位于枕叶的外侧后部，紧邻运动敏感区域MT/V5的后部，在一个称为外侧枕叶复合体（LO）的区域。与广泛的纹理图案相比，LO对物体图像表现出优先激活。这种激活不是由物体与纹理图像在傅里叶空间频率含量上的全局差异引起的，因为与功率谱匹配但相位随机化的纹理相比，物体图像产生了增强的LO激活。对物体的优先激活也不能用不同的眼动模式来解释：当受试者注视物体和用眼睛扫描物体时，观察到相似程度的激活。诸如空间频率滤波和视觉大小四倍变化等额外操作不会影响LO激活。这些结果表明，对物体增强的反应不是低水平视觉处理的表现。“林肯”错觉产生了一个引人注目的证明，即LO中的活动与物体可检测性独特相关，在这种错觉中，数字化为大块的物体模糊反而增加了它们的可识别性。这种模糊导致LO激活显著增强。尽管对物体有优先激活，但LO似乎并未参与识别过程的最终“语义”阶段。因此，在可识别性上有很大差异的物体（例如著名面孔、常见物体和不熟悉的三维抽象雕塑）对其激活程度相似。因此，这些结果证明了在人类视觉皮层中导致物体识别的处理阶段链中的一个中间环节。
