Colour, Form, and Motion Lab, School of Psychology, The University of Sydney, Australia; Australian Research Council Centre for Excellence in Vision Science, Australia.
Neuroimage. 2010 Aug 15;52(2):600-5. doi: 10.1016/j.neuroimage.2010.04.248. Epub 2010 Apr 29.
Perception of the spatial structure of the environment results from visual system processes which integrate local information to produce global percepts. Here, we investigated whether particular global spatial arrangements evoke greater responses in the human visual system, and how such anisotropies relate to those evident in the responses to the local elements that comprise the global form. We presented observers with Glass patterns; images composed of randomly positioned dot pairings (dipoles) spatially arranged to produce a percept of translational or polar global form. We used functional magnetic resonance imaging (fMRI) to infer the magnitude of neural activity within early retinotopic regions of visual cortex (V1, V2, V3, V3A/B, and hV4) while the angular arrangement of the dipoles was modulated over time to sample the range of orientations. For both translational and polar Glass patterns, V1 showed an increased response to vertical dipole orientations and all visual areas showed a bias towards dipole orientations that were radial to the point of fixation. However, areas V1, V2, V3, and hV4 also demonstrated a bias, only present for polar Glass patterns, towards dipole orientations that were tangential to the point of fixation. This enhanced response to tangential orientations within polar form indicates sensitivity to curvature or more global form characteristics as early as primary visual cortex.
对环境空间结构的感知源于视觉系统的处理过程,这些过程整合局部信息以产生全局感知。在这里,我们研究了特定的全局空间排列是否会引起人类视觉系统更大的反应,以及这种各向异性与组成全局形状的局部元素的反应中明显的各向异性有何关系。我们向观察者展示了 Glass 图案;这些图像由随机位置的点对(偶极子)组成,空间排列产生平移或极形式的全局感知。我们使用功能磁共振成像 (fMRI) 来推断视觉皮层早期视网膜区域(V1、V2、V3、V3A/B 和 hV4)内神经活动的幅度,同时偶极子的角度排列随时间调制以采样方向范围。对于平移和极形式的 Glass 图案,V1 对垂直偶极子方向的反应增强,所有视觉区域都偏向于与注视点呈放射状的偶极子方向。然而,V1、V2、V3 和 hV4 区域也表现出一种偏向,仅在极形式的 Glass 图案中出现,偏向于与注视点相切的偶极子方向。这种对极形式中切向方向的增强反应表明,早在初级视觉皮层就对曲率或更全局的形状特征具有敏感性。