The Neural Basis Of Chinese Characters Processing In Developmental Dyslexia

People with developmental dyslexia have normal intelligence and educational backgrounds,but their reading performance are significantly lower than their peers.Studies based on Western alphabetic languages have found that the defect in phonological processing is likely to be the core symptoms of dyslexia,which is related to dysfunction in the occipitaltemporal region,temporal-parietal region and inferior frontal gyrus in the left hemisphere of the brain.Written Chinese belongs to logographic system,which differs from alphabetic system in terms of how the written symbols map onto the sound.Previous studies have also shown that the neural basis for the phonological and orthographical processing during Chinese reading differs from that for alphabetic languages.However,it remains unclear as to the underlying neural mechanism of Chinese dyslexia,especially the neural basis at the brain network level.In this study,we used magnetic resonance imaging(MRI)technique to collect functional and structural data in 42 children(15 dyslexia children and 27 age-matched children).f MRI data were collected when the children were performing Chinese reading tasks(including homophone judgment,character judgment and component combination judgment).We compared neuroimaging data between dyslexic children and normal children from the perspectives of brain functional localization,structural differences and functional complex network.Analysis of complex network was performed based on graph theory.The results showed that there were dysfunctions in the dorsal and ventral pathways of dyslexic children when they performed the homophone judgment task and character judgment task,and in the dorsal pathway when they performed the component combination task,but no significant defects were found in the gray matter volume.Complex network analysis showed that the global properties of brain function network did not differ between dyslexic children and normal children,but there were some regions showing atypical regional properties in the dyslexic children.Dyslexic children have a higher degree of centralization in key brain regions such as the middle frontal gyrus,precuneus,opercular inferior frontal gyrus and superior temporal gyrus in the left hemisphere,possibly because of a compensatory function in these regions.This study provides insights into the neural mechanism of Chinese dyslexia from the perspectives of both functional localization and complex network properties.