Meta-analysis Of Chinese Reading Neural Mechanisms

Previous neuroimaging studies have shown that,Chinese reading has unique neural mechanisms compared to those in the alphabetic languages such as English.It has been consistently found that the middle frontal gyrus,the inferior and superior parietal lobule and the ventral occipitotemporal cortices are involved in Chinese reading processing,whereas these neural systems are not greatly involved in alphabetic reading.However,how the neural systems for Chinese processing are affected by age and language tasks has not been studied systematically.The areas of activation for reading processing are different in different studies,which may be due to the influence of the experimental paradigms,task design and the characteristics of the subject.The activation likelihood estimation(ALE)method can minimize the effects of the task design and the subject within group.Hence,by synthesizing the fMRI data from a large number of studies,we performed two ALE meta-analysis experiments to examine how the mechanisms of Chinese reading processing are influenced by age and experimental tasks,and discuss the differences of Chinese and alphabetic reading.First,we studied the effect of age on the neural mechanism of Chinese reading.We pooled thirty-four studies on meta-analysis,including twenty-five studies using adults as subjects and nine using children as subjects.In the light of comparative analysis,we found the two groups showed convergent activation areas,including the left inferior frontal gyrus,the left middle frontal gyrus,the bilateral fusiform gyrus,and the left middle occipital gyrus.As age increases,the activation was found increased in several right brain areas,such as the right middle frontal gyrus,the right precuneus,and the right middle occipital gyrus.The activation of these regions was enhanced,which may be more dependent on orthography processing.In the contrary,the left inferior frontal gyrus showed decreased activity during development.It may be that people could more easily select relevant semantic knowledge with the improvement of reading ability.Second,we studied the effect of tasks on the neural mechanism of Chinese reading.We synthesized data from forty-six studies,including seventeen studies with orthographical tasks,fourteen with phonological tasks,and fifteen with semantic tasks.According to ALE analysis,we found a common brain network,including the bilateral middle frontal gyrus,the left inferior frontal gyrus,the left fusiform gyrus,the right middle occipital gyrus,and the bilateral superior parietal lobule.This network was the basis of Chinese reading processing.Moreover,we compared phonological and semantic tasks with orthographical,and found a brain area of functional dissociation,namely,the left inferior frontal gyrus.Its posterior portion was more involved in phonological processing,and the anterior portion was more involved in semantic processing.Although it was the left middle frontal gyrus that played a very important role in Chinese reading processing,its function was a long-debated issue nowadays.We found,the left middle frontal gyrus is activated with different tasks and there was no functional dissociation in the contrastive analysis.Therefore,this region may be involved in the integration of orthographical,phonological,and semantic information.Finally,we studied the effect of age on the neural mechanism of Alphabetic reading.We pooled forty-two studies on meta-analysis,including twenty-three studies using adults as subjects and twenty-one using children as subjects.According to ALE analysis,we found a common brain network,including the left inferior frontal gyrus,the left fusiform gyrus,the left angular gyrus and the left superior frontal gyrus.This network was the basic brain network for alphabetic reading.Furthermore,we found the right cerebellum was activated stronger in adult,suggesting this area may be more closely projected to the prefrontal cortex.In short,by comparing the differences of brain function at different age groups and different tasks,we found that(1)the left middle frontal gyrus was not affected by the factors of age and task.It may play a very important role in the integration of orthographical,phonological,and semantic information and it may come to play the crucial role at the early stage of learning to read.(2)the right middle frontal gyrus,the bilateral superior parietal lobule and the right ventral occipitotemporal area were affected by age factors,suggesting that people may be more dependent on orthographical processing as age increases.(3)the left inferior frontal gyrus was affected by both age and language task and it showed a functional dissociation during reading.(4)compared with Alphabetic,Chinese has more activation in the right brain areas,indicating that Chinese reading needs more visual-spatial processing.