An FMRI Study On Chinese Characters Recognition For Skilled And Less Skilled Deaf Readers

Deaf people usually don't have access to phonetic forms of some language that is encoded by print,when the process of learning to read is altered by deafness rather by a specific reading disability.Although reading outcomes are generally poor for deaf people,some deaf individuals do,nonetheless,achieve high levels of reading proficiency.Very little is known about the difference of neural underpinnings between skilled and less skilled deaf readers when reading Chinese.The only one research in deaf people reading Chinese characters simply compare groups of deaf and hearing readers without regard to the variability of reading skill or language background within the deaf group(Li et al.,2014).Here we take advantage of specific properties of the Chinese writing system to test how differential availability of sublexical information about sound and meaning,as well as the orthographic structure of characters,pseudo-characters and “artificial” control stimuli influence brain activation in the context of the lexical decision task.The goal of the present study is to identify possible neural signatures that differentiate between skilled and less skilled reading in deaf adults,and to compare skilled deaf readers and hearing control group in the process of Chinese characters recognition.There is a certain commonality in neural mechanism between skilled deaf readers and hearing control group in the processing of Chinese character recognition,which indicates that the partial reading network of human brain has not been changed by hearing impairment.There is no significant difference between the two groups in the visual word form area,suggesting that early auditory input is not necessary for the development of the visual word form area in the deaf.However,comparing with the hearing control group,the right anterior cingulum in skilled deaf readers was significantly activated in the semantic processing,indicating that there was a certain difference in the allocation of cognitive resources between skilled deaf readers and hearing people.Therefore this study considers that skilled deaf readers and hearing people did not show significant difference in the brain activation when processing orthographical and phonological information,two kinds of sublexical information,while hearing status may only affects the processing of semantical information.There was also no significant difference between skilled deaf readers and less skilled deaf readers in the orthographical and phonological processing.In the semantical processing,the left middle frontal gyrus and the ventral part of the inferior frontal gyrus was more activated in skilled deaf readers than in the less skilled deaf readers.Therefore,this study suggests that the difference of reading proficiency in deaf people is more related to the efficiency of semantical processing in Chinese character recognition.Correlation analysis further found that reading proficiency was significantly correlated with the brain activation in orthographical and semantical processing.Specifically,the higher the reading proficiency of the deaf is,the stronger the activation of the bilateral middle fusiform gyrus,the left frontal gyrus in the orthographical processing and the middle temporal gyrus and angular gyrus in the semantic processing are.The brain activation of phonological processing showed no significant correlation with reading proficiency.Given the middle fusiform gyrus and the middle temporal gyrus lies in the ventral reading network,and play an important role in the orthographysemantic mapping pathway,this study suggests the deaf readers may be more inclined to use the ventral orthography-semantic direct pathway in lexical access.We also found that the activation of the left superior temporal gyrus of the deaf in orthographical processing,partly explained auditory cortex re-organization after deafness.This study compares the neural network of Chinese character recognition between skilled and less skilled deaf readers,so that we can directly identify how reading profiency affects the function of reading network in deaf adults,ruling out the influence of other variables on cerebral cortex.Moreover,the invisible experimental paradigm adopted in this research draws more attention to automatical activation of phonetic and semantic information in word recognition,providing a new perspective for us to understand the neural basis of deaf people in reading.