Neural Correlates of the Cognitive Processes in Chinese Word Recognition
|Keywords||Lexical decision Inferior frontal gyrus Pseudo words Chinese fMRI|
Objective We use functional magnetic resonance imaging (fMRI) to identify the cortical areas engaged during Chinese word processing, and to contrast the cortical areas involved in Chinese and other alphabetical languages. And we emphasize on the difference between the neural substrates of lexical processing of Chinese real words and pseudo words, trying supplying a new proof for the neural substrates of orthography to phonology transformation.Materials and Methods Fourteen right-handed, native Chinese university students participated this study. They were instructed to perform a visual lexical decision task while being scanned with a 1.5T MRI scanner with a list of randomly intermixed real and pseudo Chinese two-character (or two-syllable) words tasks. Event-related designing was performed during this experiment, fMRI data were collected, data analysis was carried out using spm2 software, a cross correlation analysis were used to statistically generate the activation map.Results The behavioral performance showed that pseudo words were significantly slower than real words while there were no difference in their accuracy. And we found that the processing of real words and pseudo words activated a highly comparable neural network, including bilateral inferior frontal gyrus (IFG), middle temporal gyrus, fusiform gyrus, lingual gyms, supramarginal gyrus and thalamus. However, left inferior frontal gyrus (BA 44/45) was significantly more activated in pseudo word processing than in real word processing. And the activation in left supramarginal gyrus was of a much larger volume for real words than for pseudo words,Conclusions 1. The processing of real words and pseudo words activated a highly comparable neural network showed that these cortical areas were involved with word processing which were referred in previous studies. 2. Comparing with the cortical areas of alphabetical language, we found some special areas for Chinese, suggesting the areas related with visual-spatial analysis for Chinese are larger than for other alphabetical language. 3. Mirroring a behavioral lexical effect, left inferior frontal gyrus (IFG) was significantly more activated for pseudo words than for real words. This result does not support the view that left IFG plays a role in grapheme-to-phoneme conversion. Rather, increased activity in this area for pseudo words is attributed to the phonological information storage, or differences in general decision making processes, specifically in making positive versus negative responses. 4.Finally, activation in left supramarginal gyrus was of a much larger volume for real words than for pseudo words, suggesting a role of this region in the representation of phonological and/or semantic information of two-character Chinese words at the lexical level.