Center for Studies of Psychological Application and School of Psychology, South China Normal University, Guangzhou, 510631, China.
Center for Psychology and Brain Science and Department of Psychology, Guangzhou University, Guangzhou, 510006, China.
Sci Rep. 2017 Jun 12;7(1):3279. doi: 10.1038/s41598-017-03652-6.
The perceived size of an object remains relatively constant although its retinal size keeps decreasing as the object moves away along the depth dimension of the 3D space, i.e. size constancy. Neural mechanisms generating size constancy in virtual 3D space, however, remain poorly understood. By constructing a virtual 3D world in the MR scanner, we positioned the same 3D objects either near or far from the observers so that the near and far objects were perceived as having the same physical size despite their differences in retinal size. To control for the effect of differential retinal size, an additional 2D condition was introduced: a large and a small object, with matched retinal images as the near and far objects in the 3D condition, respectively, were presented on a 2D screen. Differences in retinal size activated overlapped areas in bilateral inferior occipital gyrus (IOG) in both experiments. The overlapped areas in IOG, however, showed different patterns of functional connectivity with different neural networks, depending on the perceived size of objects. In particular, IOG showed enhanced connectivity with bilateral superior parietal cortex in the 2D condition, but with inferior temporal and prefrontal cortex in the virtual 3D condition, i.e., size constancy.
尽管物体在沿着三维空间的深度维度移动时，其视网膜大小不断减小，但人们对物体大小的感知却相对保持不变，即大小恒常性。然而，产生虚拟三维空间中大小恒常性的神经机制仍知之甚少。通过在磁共振扫描仪中构建一个虚拟的 3D 世界，我们将相同的 3D 物体置于观察者附近或远处，使得近物和远物尽管视网膜大小不同，但被感知为具有相同的物理大小。为了控制视网膜大小差异的影响，引入了一个额外的 2D 条件：一个大物体和一个小物体，它们的视网膜图像分别与 3D 条件中的近物和远物匹配，在 2D 屏幕上呈现。在两个实验中，视网膜大小的差异激活了双侧下枕叶回（IOG）的重叠区域。然而，IOG 的重叠区域与不同的神经网络显示出不同的功能连接模式，这取决于物体的感知大小。特别是，IOG 在 2D 条件下与双侧顶叶上回显示出增强的连通性，但在虚拟 3D 条件下与下颞叶和前额叶皮层显示出增强的连通性，即大小恒常性。
