Identification and characterization of the Visual Character Form Area (VCFA) in Chinese readers and illiterates

Abstract

 

Written language represents a special category of visual information. Literate people have extensive visual experience and expertise with written language, yet reading skills have to be acquired with serious effort over many years. The question of whether there are specialized neural mechanisms and cortical modules for visual word processing is important and remains debated. Three issues were investigated in this study: category selectivity in the mid-fusiform cortex, orthographic sensitivity of the presumed VCFA, and experience-dependency of its development. First, we examined category selectivity for Chinese characters in native Chinese readers as well as native Chinese illiterates and native English readers. A detailed distribution of BOLD signals across the mid-fusiform cortical surface and the spatial pattern of responses to Chinese characters were obtained. Results show that a region with peaked response to Chinese character-like stimuli could be consistently found in the lateral part of the left fusiform gyrus in Chinese readers. Additionally, different levels of orthographic properties (i.e., characters, false-characters consisting of radicals in wrong positions, radicals, and stroke combinations) of an input stimulus were reflected in differential spatial patterns of activation across voxels, with the left lateral mid-fusiform region showing the highest specificity for Chinese characters. Finally, minimal responses to Chinese characters were found in Chinese illiterates and English readers, supporting the idea that functional specialization and response selectivity to written language in the mid-fusiform cortex is experience dependent.