School of Psychology, University of Sydney, Sydney, NSW 2006, Australia.
Cereb Cortex. 2010 Aug;20(8):1946-54. doi: 10.1093/cercor/bhp265. Epub 2009 Dec 17.
The processing of color and form is largely segregated within the visual brain. But there is also evidence to suggest that these features are coded in combination early in visual processing. Here, we combined high-resolution functional magnetic resonance imaging (fMRI) together with multivariate pattern classification to examine where in the visual cortex specific color form "conjunctions" are represented. Human subjects viewed visual displays containing colored spiral patterns. The spiral patterns could be red or green, and oriented either clockwise or counterclockwise, leading to 4 possible stimulus configurations. Two additional displays combined 2 of the above single color-form pairings, leading to double conjunctions. We applied linear classifiers to voxel activation patterns obtained while subjects viewed such displays. Our findings not only show that color and form information is coded across retinotopically defined visual areas, but also that the 2 double-conjunction stimuli can be distinguished. The voxels most informative about conjunctions were distinct from those most informative about color or form alone. Our results indicate that conjunctions of form and color may be coded by separate functional units as early as primary visual cortex. The results of this study have implications for theories concerning the segregation and binding of color and form information.
颜色和形状的处理在很大程度上是在视觉大脑中分离的。但也有证据表明，这些特征在视觉处理的早期就以组合的形式进行编码。在这里，我们结合高分辨率功能磁共振成像（fMRI）和多元模式分类，研究了特定颜色形状“组合”在视觉皮层中的何处被表示。人类受试者观看包含彩色螺旋图案的视觉显示器。螺旋图案可以是红色或绿色，并且可以顺时针或逆时针方向定向，导致 4 种可能的刺激配置。另外两个显示组合了上述两种单一颜色-形状配对，导致双重组合。当受试者观看此类显示时，我们应用线性分类器对体素激活模式进行分类。我们的发现不仅表明颜色和形状信息在视网膜定义的视觉区域中进行编码，而且还表明可以区分这两个双重组合刺激。关于组合的体素与关于颜色或形状的体素不同，是最具信息量的。我们的结果表明，形式和颜色的组合可能早在初级视觉皮层就由单独的功能单元编码。这项研究的结果对关于颜色和形状信息的分离和结合的理论具有影响。
