The Functional Electrical Neuroimaging Laboratory, Neuropsychology and Neurorehabilitation Service, Department of Clinical Neurosciences, Vaudois University Hospital Center and University of Lausanne, 1011 Lausanne, Switzerland.
Neuroimage. 2012 Feb 1;59(3):2808-17. doi: 10.1016/j.neuroimage.2011.09.031. Epub 2011 Sep 22.
Despite myriad studies, neurophysiologic mechanisms mediating illusory contour (IC) sensitivity remain controversial. Among the competing models one favors feed-forward effects within lower-tier cortices (V1/V2). Another situates IC sensitivity first within higher-tier cortices, principally lateral-occipital cortices (LOC), with later feedback effects in V1/V2. Still others postulate that LOC are sensitive to salient regions demarcated by the inducing stimuli, whereas V1/V2 effects specifically support IC sensitivity. We resolved these discordances by using misaligned line gratings, oriented either horizontally or vertically, to induce ICs. Line orientation provides an established assay of V1/V2 modulations independently of IC presence, and gratings lack salient regions. Electrical neuroimaging analyses of visual evoked potentials (VEPs) disambiguated the relative timing and localization of IC sensitivity with respect to that for grating orientation. Millisecond-by-millisecond analyses of VEPs and distributed source estimations revealed a main effect of grating orientation beginning at 65 ms post-stimulus onset within the calcarine sulcus that was followed by a main effect of IC presence beginning at 85 ms post-stimulus onset within the LOC. There was no evidence for differential processing of ICs as a function of the orientation of the grating. These results support models wherein IC sensitivity occurs first within the LOC.
尽管有无数的研究，但介导错觉轮廓（IC）敏感性的神经生理机制仍然存在争议。在竞争模型中，有一种模型支持较低层次皮质（V1/V2）中的前馈效应。另一种模型则将 IC 敏感性首先定位于较高层次的皮质，主要是外侧枕叶皮质（LOC），然后在 V1/V2 中产生反馈效应。还有一些模型假设 LOC 对由诱导刺激划定的显著区域敏感，而 V1/V2 效应则专门支持 IC 敏感性。我们通过使用定向为水平或垂直的未对齐线光栅来诱导 IC，解决了这些分歧。线方向提供了一种已建立的 V1/V2 调制测定方法，与 IC 的存在无关，并且光栅没有显著区域。视觉诱发电位（VEPs）的电神经影像学分析阐明了 IC 敏感性相对于光栅方向的相对时间和定位。对 VEPs 和分布式源估计的毫秒级分析显示，在刺激后 65 毫秒内，在距状裂内出现了光栅方向的主要效应，随后在刺激后 85 毫秒内，在 LOC 内出现了 IC 存在的主要效应。没有证据表明 IC 作为光栅方向的函数进行了不同的处理。这些结果支持了这样的模型，即在 LOC 内首先出现 IC 敏感性。
