Résumé
To study the visual magnocellular deficit in alphabetic and Chinese developmental dyslex?ia from behavioral,neural mechanism and intervention studies,critical words in Chinese and English (de?velopmental dyslexia and magnocellular pathway or dorsal stream or contrast sensitivity or coherent mo?tion ) were searched in Chinese and English databases(CNKI,PubMed,ScienceDirect,etc.) from Septem?ber to December,2015. Forty?three relevant articles which aimed to investigate the visual magnocellular defi?cit in developmental dyslexia were selected among 75 articles according to the searching result and the objec?tive of the present study. The results showed that alphabetic studies consistently consistently manifested the magnocellular deficit in developmental dyslexia from the aspects of behavioral performance,neural activities and intervention effects. However,whether the deficit was the cause or the consequence of dyslexia remains controversial. In Chinese,most of studies on magnocellular deficit of developmental dyslexia were behavioral. There were few studies from aspects of neural mechanism and intervention. Alphabetic and Chinese studies consistently manifested magnocellular deficit in developmental dyslexia,suggesting the consistency across lan?guages. However,more comprehensive studies are required to further explore the causal relationship between magnocellular deficit and developmental dyslexia.
Résumé
Objective To study on the neural mechanism of deficits in Chinese developmental dyslexia from the aspects of the phonological processing,orthographic skills,visual magnocellular function and cerebellum function.Methods Critical words in Chinese and English (e.g.dyslexia,reading development,Chinese,neural) and formula (e.g.Chinese and (reading development) and (neural or neuroimage or fMRI or ERP or brain area) related with the present topic were searched among the article abstracts in Chinese and foreign databases (e.g.CNKI,Pubmed,Sciencedirect) from July to December,2014.Results Fifty-two relevant articles were gained access to the database.Referring to the present topic,research on the neural mechanism of dyslexia with neuroimaging technique was reserved,while the studies in which the reading impairment of the participants was caused by acquired factors were eliminated.Finally,thirty-three valid articles were retained.Conclusion According to previous studies,although there might be similarities in cognitive deficits of dyslexia between alphabetic languages and Chinese,it was still found that the Chinese children with developmental dyslexia exhibited abnormal neural activities and impaired brain structures in areas associated with Chinese phonology (i.e.left middle frontal gyrus,which was different from the left inferior fiontal gyrus always related with phonological processing in alphabetic languages) and orthographic skills (right occipitotemporal areas which was responsible for the visuospatial processing),revealing language specificity of Chinese to some extent.However,some other studies reported the similarities in neural mechanisms of dyslexia across languages.Therefore,more studies were required to further examine the crosscultural mechanism of the neural activity regarding the developmental dyslexia.Meanwhile,researches on the aspects of general perception showed Chinese dyslexic individuals had deficits in visual magnocellular function,and cerebellum.Future studies were required to explore the relationship between the linguistic and non-linguistic deficits.