Laboratory of Experimental Psychology, University of Leuven (K.U.Leuven), Tiensestraat 102, 3000 Leuven, Belgium.
Neuroimage. 2010 Feb 15;49(4):3248-56. doi: 10.1016/j.neuroimage.2009.11.036. Epub 2009 Dec 4.
Research into the organization of high-level visual cortex has mainly used discrete object classes (e.g. faces and buildings). In contrast, the lower levels of the visual cortex have mainly been studied using phase-encoding techniques with gradually changing rotating wedges and expanding/contracting rings. The gradual stimulus changes cause traveling waves on the cortical surface and time delays of each cortical location are related to stimulus preference. We propose to extend this method to study higher-order properties of visual objects. We created gradual morphing sequences from a face into a building and vice versa. The activation in traditional face- and house-selective regions corresponding to fusiform face area (FFA) and parahippocampal place area (PPA) was time-locked to presentation of respectively face(-like) and building(-like) stimuli in the morphing sequences. We also included contracting/expanding rings containing images of parts of natural scenes. Confirming existing literature with discrete object classes, activity in FFA and PPA was time-locked to the presentation of foveal and eccentric rings, respectively. The results however contradict large-scale continuous maps across the ventral visual stream, as the cortical area between FFA and PPA was not modulated by the position in the morphing sequences, or by the retinotopic position of the rings. We conclude that phase-encoding techniques can help in revealing the organization of high-level visual regions for complex object properties.
针对高级视皮层组织的研究主要使用离散的物体类别（如人脸和建筑物）。相比之下，视皮层的较低层次主要使用相位编码技术进行研究，该技术使用逐渐变化的旋转楔形和扩张/收缩环。逐渐变化的刺激会在皮质表面上产生行波，并且每个皮质位置的时间延迟与刺激偏好相关。我们建议将该方法扩展到研究视觉对象的更高阶属性。我们从人脸逐渐变形为建筑物，反之亦然，创建了逐渐变形的序列。在传统的面选择性和房子选择性区域（分别对应梭状回面部区域（FFA）和海马旁回位置区域（PPA））中的激活与逐渐变形序列中呈现的分别类似人脸和类似建筑物的刺激同步。我们还包括包含自然场景部分图像的收缩/扩张环。与离散物体类别确认现有文献一致，FFA 和 PPA 的活动与中央凹和偏心环的呈现同步。然而，结果与腹侧视觉流中的大规模连续图谱相矛盾，因为 FFA 和 PPA 之间的皮质区域不受变形序列中位置或环的视网膜位置的调制。我们得出结论，相位编码技术有助于揭示复杂物体属性的高级视觉区域的组织。
