Working-memory training improves developmental dyslexia in Chinese children

Although plasticity in the neural system underlies working memory, and working memory can be improved by training, there is thus far no evidence that children with developmental dyslexia can benefit from working-memory training. In the present study, thirty dyslexic children aged 8-11 years were recruited from an elementary school in Wuhan, China. They received working-memory training including training in visuospatial memory, verbal memory, and central executive tasks. The difficulty of the tasks was adjusted based on the performance of each subject, and the training sessions lasted 40 minutes per day, for 5 weeks. The results showed that working-memory training significantly enhanced performance on the nontrained working memory tasks such as the visuospatial, the verbal domains, and central executive tasks in children with developmental dyslexia. More importantly, the visual rhyming task and reading fluency task were also significantly improved by training. Progress on working memory measures was related to changes in reading skills. These experimental findings indicate that working memory is a pivotal factor in reading development among children with developmental dyslexia, and interventions to improve working memory may help dyslexic children to become more proficient in reading.

Eye-movement Patterns of Chinese Children with Developmental Dyslexia during the Stroop Test

Objective To compare the eye-movement patterns of Chinese children with developmental dyslexia（DD children） with those of non-dyslexic children as they perform the Stroop Color and Word Test（SCWT）, and to explore the relationship between their eye-movement patterns and interference effect. Methods An EyeLink II was used to record the eye-movement parameters of 32 DD children and 37 non-dyslexic children as they performed the SCWT. The independent samples t-test and repeated measures were used to analyze behavioral and eye-movement parameters. Results Compared to the control group, Chinese DD children presented lower accuracy（F = 8.488）, slower response time（F = 25.306）, and larger interference effect（t = 2.29）; Chinese DD children also exhibited lower frequency of fixations（F = 6.069）, greater numbers of saccades（F = 7.914） and fixations（F = 5.272）, and shorter mean saccade distance（F = 4.03）. All behavioral and eye-movement parameters differed significantly among the three tasks in the SCWT. There was significant interaction between groups and tasks in accuracy（F = 5.844）, and marginally significant interaction in response time（F = 3.040）. Chinese DD children tended to have lower accuracy and longer response time than the control group in the ＇color-word naming＇ task. Conclusion Compared to non-dyslexic children, Chinese DD children are subject to a stronger interference effect. When performing the SCWT, Chinese DD children exhibit abnormal eye-movement patterns, namely shorter mean saccade distance, lower frequency of fixations, and more fixations and saccades. These abnormal eye movements may be relatively stable oculomotor patterns of DD children performing visual processing, and not influenced by impaired interference effect.

Altered electroencephalographic networks in developmental dyslexia after remedial training:a prospective case-control study

Electroencephalographic studies using graph theoretic analysis have found aberrations in functional connectivity in children with developmental dyslexia.However,how the training with visual tasks can change the functional connectivity of the semantic network in developmental dyslexia is still unclear.We looked for differences in local and global topological properties of functional networks between 21 healthy controls and 22 dyslexic children(8–9 years old)before and after training with visual tasks in this prospective case-control study.The minimum spanning tree method was used to construct the subjects’brain networks in multiple electroencephalographic frequency ranges during a visual word/pseudoword discrimination task.We found group differences in the theta,alpha,beta and gamma bands for four graph measures suggesting a more integrated network topology in dyslexics before the training compared to controls.After training,the network topology of dyslexic children had become more segregated and similar to that of the controls.In theθ,αandβ1-frequency bands,compared to the controls,the pre-training dyslexics exhibited a reduced degree and betweenness centrality of the left anterior temporal and parietal regions.The simultaneous appearance in the left hemisphere of hubs in temporal and parietal(α,β1),temporal and superior frontal cortex(θ,α),parietal and occipitotemporal cortices(β1),identified in the networks of normally developing children was not present in the brain networks of dyslexics.After training,the hub distribution for dyslexics in the theta and beta1 bands had become similar to that of the controls.In summary,our findings point to a less efficient network configuration in dyslexics compared to a more optimal global organization in the controls.This is the first study to investigate the topological organization of functional brain networks of Bulgarian dyslexic children.Approval for the study was obtained from the Ethics Committee of the Institute of Neurobiology and the Institute for Population and Human Studies,Bulgarian Academy of Sciences(approval No.02-41/12.07.2019)on March 28,2017,and the State Logopedic Center and the Ministry of Education and Science(approval No.09-69/14.03.2017)on July 12,2019.

DCDC2 gene polymorphisms are associated with developmental dyslexia in Chinese Uyghur children

Developmental dyslexia is a complex reading and writing disorder with strong genetic components. In previous genetic studies about dyslexia, a number of candidate genes have been identified. These include DCDC2, which has repeatedly been associated with developmental dyslexia in various European and American populations. However, data regarding this relationship are varied according to population. The Uyghur people of China represent a Eurasian population with an interesting genetic profile. Thus, this group may provide useful information about the association between DCDC2 gene polymorphisms and dyslexia. In the current study, we examined genetic data from 392 Uyghur children aged 8–12 years old from the Xinjiang Uyghur Autonomous Region of China. Participants included 196 children with dyslexia and 196 grade-, age-, and gender-matched controls. DNA was isolated from oral mucosal cell samples and fourteen single nucleotide polymorphisms（rs6456593, rs1419228, rs34647318, rs9467075, rs793862, rs9295619, rs807701, rs807724, rs2274305, rs7765678, rs4599626, rs6922023, rs3765502, and rs1087266） in DCDC2 were screened via the SNPscan method. We compared SNP frequencies in five models（Codominant, Dominant, Recessive, Heterozygote advantage, and Allele） between the two groups by means of the chi-squared test. A single-locus analysis indicated that, with regard to the allele frequency of these polymorphisms, three SNPs（rs807724, rs2274305, and rs4599626） were associated with dyslexia. rs9467075 and rs2274305 displayed significant associations with developmental dyslexia under the dominant model. rs6456593 and rs6922023 were significantly associated with developmental dyslexia under the dominant model and in the heterozygous genotype. Additionally, we discovered that the T-G-C-T of the four-marker haplotype（rs9295619-rs807701-rs807724-rs2274305） and the T-A of the two-marker haplotype（rs3765502-1087266） were significantly different between cases and controls. Thus, we conclude that DCDC2 gene polymorphisms are associated with developmental dyslexia in Chinese Uyghur children.

Prevalence of developmental dyslexia in primary school children:a protocol for systematic review and meta-analysis

Background Developmental dyslexia(DD)is a specific impairment during the acquisition of reading skills and may have a lifelong negative impact on individuals.Reliable estimates of the prevalence of DD serve as the basis for evidence-based health resource allocation and policy making.However,the prevalence of DD in primary school children varies largely across studies.Moreover,it is unclear whether there are differences in prevalence in different genders and writing systems.Hence,the present study aims to conduct a systematic review and meta-analysis to assess the global prevalence of DD and to explore related factors.Methods We will undertake a comprehensive literature search in 14 databases,including EMBASE,PubMed,Web of Science,China National Knowledge Infrastructure and Cochrane,from their inception to June 2021.Cross-sectional and longitudinal studies that describe the prevalence of DD will be eligible.The quality of the included observational studies will be assessed using the Strengthening the Reporting of Observational Studies in Epidemiology statement.The risk of bias will be determined by sensitivity analysis to identify publication bias.Results One meta-analysis will be conducted to estimate the prevalence of DD in primary school children.Heterogeneity will be assessed in terms of the properties of subjects(e.g.,gender,grade and writing system)and method of diagnosis in the included primary studies.Subgroup analyses will also be performed for population and secondary outcomes.Conclusion The results will synthesize the prevalence of DD and provide information for policy-makers and public health specialists.

Orthographic Processing of Developmental Dyslexic Children in China: Evidence from an Event-Related Potential Study

Objective:This study aimed to explore the orthographic processing of simplified Chinese characters in developmental dyslexic children in Kashgar,Xinjiang,China,and provide a theoretical basis for intervention strategies for developmental dyslexia in Chinese.Methods:Using event-related potential(ERP)measures,18 developmental dyslexic children and 23 typically developing children performed a character decision task with three types of stimuli:real characters(RCs),pseudocharacters(PCs),and noncharacters(NCs).Results:Behavioral results showed that the control children displayed a faster and higher accurate performance than the dyslexic children across PCs and NCs.ERP data revealed that the RCs and PCs elicited a stronger P200 than the NCs.Compared with the RCs and NCs,children in the control group showed more N400 negatives for PCs.It is worth mentioning that dyslexic children did not show any difference on N400,which reflected the insufficient orthographic processing of dyslexic children in China.Conclusion:These results show that Chinese dyslexic children had orthographic processing defects.

Eye movements characteristics of Chinese dyslexic children in picture searching

Background Reading Chinese, a kind of ideogram, relies more on visual cognition. The visuospatial cognitive deficit of Chinese dyslexia is an interesting topic that has received much attention. The purpose of current research was to explore the visuopatial cognitive characteristics of Chinese dyslexic children by studying their eye movements via a picture searching test. Methods According to the diagnostic criteria defined by ICD-10, twenty-eight dyslexic children （mean age （10.12±1.42） years） were enrolled from the Clinic of Children Behavioral Disorder in the third affiliated hospital of Sun Yat-sen University. And 28 normally reading children （mean age （10.06±1.29） years）, 1：1 matched by age, sex, grade and family condition were chosen from an elementary school in Guangzhou as a control group. Four groups of pictures （cock, accident, canyon, meditate） from Picture Vocabulary Test were chosen as eye movement experiment targets. All the subjects carried out the picture searching task and their eye movement data were recorded by an Eyelink II High-Speed Eye Tracker. The duration time, average fixation duration, average saccade amplitude, fixation counts and saccade counts were compared between the two groups of children. Results The dyslexic children had longer total fixation duration and average fixation duration （F=-7.711, P 〈0.01; F=-4.520, P 〈0.05）, more fixation counts and saccade counts （F=-7.498, P 〈0.01; F=-11.040, P 〈0.01）, and a smaller average saccade amplitude （F=-29.743, P 〈0.01） compared with controls. But their performance in the picture vocabulary test was the same as those of the control group. The eye movement indexes were affected by the difficulty of the pictures and words, all eye movement indexes, except saccade amplitude, had a significant difference within groups （P 〈0.05）. Conclusions Chinese dyslexic children have abnormal eye movements in picture searching, applying slow fixations, more fixations and small and frequent saccades. Their abnormal eye movement mode reflects the poor ability and strategy of visual information processing.