Research Of Neural Network Of Chinese Character Phonological Processing Based On FMRI

A growing body of neuroimaging studies have shown that the neural systems for Chinese character phonological processing is different from that of alphabetic languages because Chinese and alphabetic writing systems differ in important dimensions.Since most studies on this question recruited a small number of participants and no correction procedures were used in statistical analysis,they might suffer from the false positive rate problem.In this study,we performed two experiments to identify neural activation patterns for Chinese phonological processing: one was a meta-analysis using the activation likelihood estimation(ALE)method to summarize previous findings about phonological processing of Chinese characters and examined the neural activation patterns.In the second experiment,we performed a functional magnetic resonance imaging study,with a large sample size and stringent statistical threshold to see whether or not previous findings can be validated.Homophone judgment task was devised and sixty healthy adults participated in Experiment 2.Common activation patterns in the left middle frontal gyrus,left inferior frontal gyrus,superior frontal gyrus,left precentral gyrus,left insula,bilateral middle-inferior occipital gyrus,left lingual gyrus,left fusiform gyrus were seen for the two experiments.The results are consistent with the findings of previous studies investigating Chinese phonological processing and provide better understanding of the neural networks underlying phonological processing systems.Since so many brain regions are activated in Chinese phonological processing,we then studied the connections between several key brain regions in this task from the perspective of functional integration.The motor cortex is known to be a crucial element among the neural circuits responsible for phonemic processing in speech perception,but its potential contribution to phonological processing in visual word perception is unknown.Internalized phonological activation of printed words is pivotal for building up the connection between visual form and the semantics of lexical items.Since internal phonological representation is based on auditory speech recognition,we hypothesize that the motor cortex may be a crucial component of the distributed brain networks that subserve phonological processing in reading.Using functional MRI,we found that in a task requiring subjects to judge whether two visually unrelated Chinese characters are pronounced alike(visual homophone task),a close link was seen between the left middle frontal cortex for phonological processing in reading and the premotor cortex as well as between the left middle frontal cortex and the supplementary motor area(SMA).Further analysis of Experiment 3(Chinese component search task)revealed that the connections from language regions to the motor circuits were limited to phonological processing and did not apply to the visual form of the characters,indicating that the association of motor regions with visual word recognition is phonologically modulated.Our study has demonstrated that the motor cortex plays an important role in word perception in the visual modality,exclusively via its connections with regions of phonological processing,thus adding an important new dimension to the investigation of the contribution of motor circuits to phonological analysis.