An Optical Imaging Study Of Left Middle Frontal Gyrus In Chinese Reading

Language,as an important and unique cognitive ability in humans,has been studied extensively in previous studies,by examining brain activity provoked by language cognitive tasks.The neural mechanisms for the processing of English(the most widely used language)and Chinese(most population used language)have been a hot topic of study in cognitive neuroscience.Previous studies have shown that there exist different brain areas for processing the two language,especially the left middle frontal gyrus,which plays a crucial role in Chines reading,whereas it play a much less important role in English reading.Previous studies have used functional magnetic resonance imaging(fMRI),electroencephalogram and event-related potential(EEG/ERP),functional near-infrared spectroscopy(fNIRS),magneto encephalography(MEG)and other imaging techniques to locate the brain areas for processing the orthographic,phonological and semantic information of Chinese characters,and to explore the time course of different components in Chinese reading.However,there is no consensus as to the time order of orthographic,phonological,semantic processing.Main theories include the direct access model and the phonological mediation model.fNIRS has some advantages over other imaging techniques.For example,compared to fMRI,it has low requirements but higher temporal resolution;compared to EEG and MEG,it has better practicability.In the study,fNIRS was used to study the time courses of neural activation in different subregions of the left middle frontal gyrus when the subjects performed orthographic,phonological and semantic tasks.Nineteen Chinese students,whose mother tongue is Chinese,performed tasks including font size judgment of Chinese characters,homophone judgment,and synonyms judgment.Results showed that: 1.Compared the left posterior part of the left middle frontal gyrus,the left anterior part of the left middle frontal gyrus has lower neural activated,earlier in the activation time.2.In the left anterior part of the left middle frontal gyrus,there were no differences between orthography、phonology and semantics activation time sequences,Phonological information was processed earlier than semantic information in the time course in the left posterior part of the left middle frontal gyrus,and orthography information was processed earlier than phonological information.Results thus support previous findings using fMRI and ERP.In conclusion,we used optical imaging method to study the process of Chinese reading and provided evidence for time courses of the neural activation during orthography,phonology and semantics.