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-memor...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.展开更多
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 ...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.展开更多
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 functi...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.展开更多
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...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.展开更多
Background: Magnocellular deficit theory is among the different hypotheses that have been proposed to explain the pathophysiology of developmental dyslexia (DD). Dysfunction of the magnocellular system in DD has been ...Background: Magnocellular deficit theory is among the different hypotheses that have been proposed to explain the pathophysiology of developmental dyslexia (DD). Dysfunction of the magnocellular system in DD has been investigated using mainly visual evoked potentials (VEPs), particularly transient VEPs, although recently abnormal steady-state VEPs have also been reported. The brain regions responsible for the abnormal VEPs in DD have yet to be elucidated, however. In this study, we performed functional magnetic resonance imaging and electroencephalography (fMRI-EEG) simultaneously to elucidate the brain areas that were found in a previous study to be activated through stimulation of the magnocellular system, and then investigated the mechanism involved in the dysfunction seen in DD.Methods: Subjects were 20 healthy individuals (TYP group;13 men, 7 women;mean ± standard deviation age, 26.3 ± 5.53 years) and 2 men with DD (aged 42 and 30 years). Images of brain activity were acquired with 3-Tesla MRI while the viewing the reversal of low-spatial frequency and low-contrast black-and-white sinusoidal gratings. EEG was recorded concurrently to obtain steady-state VEPs.Results: Stimulus frequency-dependent VEPs were observed in the posterior region of the brain in the TYP group;however, VEP amplitudes in both DD patients were clearly smaller than those in TYP. fMRI images revealed that both the primary and secondary visual cortices were activated by black-and- white sinusoidal gratings in the TYP group, whereas activity in the visual cortex overall was reduced in both DD patients.Conclusions: Present low spatial and high reversal frequency visual stimuli activated the primary visual cortex presumably through predominant activation of the magnocellular pathway. This finding indicates that some cases of adult patients of DD involve impairment of the visual magnocellular system.展开更多
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 strategi...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.展开更多
基金supported by grants from the National Natural Science Foundation of China, No. 30872132
文摘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.
基金funded by the National Natural Science Foundation of China under grant number 81302437 and title ‘A study on brain mechanisms of abnormal voluntary control of saccades in Chinese children with reading disability’the National Natural Science Foundation of China under grant number 81673197 and title ‘Brain mechanisms of Cantonese-Mandarin-English phonological processing deficits in Cantonese children with developmental dyslexia’the young teacher training program of Sun Yat-sen University(Medicine)under grant number 13ykpy11 and title ‘A comparison study on brain mechanisms of phonological processing between Cantonese-speaking children and Mandarin-speaking children with developmental dyslexia’
文摘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.
基金The study was supported by the National Science Fund of the Ministry of Education and Science(project DN05/14-2016,to JAD).
文摘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.
基金funded by the National Natural Science Foundation of China,No.81360434
文摘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.
文摘Background: Magnocellular deficit theory is among the different hypotheses that have been proposed to explain the pathophysiology of developmental dyslexia (DD). Dysfunction of the magnocellular system in DD has been investigated using mainly visual evoked potentials (VEPs), particularly transient VEPs, although recently abnormal steady-state VEPs have also been reported. The brain regions responsible for the abnormal VEPs in DD have yet to be elucidated, however. In this study, we performed functional magnetic resonance imaging and electroencephalography (fMRI-EEG) simultaneously to elucidate the brain areas that were found in a previous study to be activated through stimulation of the magnocellular system, and then investigated the mechanism involved in the dysfunction seen in DD.Methods: Subjects were 20 healthy individuals (TYP group;13 men, 7 women;mean ± standard deviation age, 26.3 ± 5.53 years) and 2 men with DD (aged 42 and 30 years). Images of brain activity were acquired with 3-Tesla MRI while the viewing the reversal of low-spatial frequency and low-contrast black-and-white sinusoidal gratings. EEG was recorded concurrently to obtain steady-state VEPs.Results: Stimulus frequency-dependent VEPs were observed in the posterior region of the brain in the TYP group;however, VEP amplitudes in both DD patients were clearly smaller than those in TYP. fMRI images revealed that both the primary and secondary visual cortices were activated by black-and- white sinusoidal gratings in the TYP group, whereas activity in the visual cortex overall was reduced in both DD patients.Conclusions: Present low spatial and high reversal frequency visual stimuli activated the primary visual cortex presumably through predominant activation of the magnocellular pathway. This finding indicates that some cases of adult patients of DD involve impairment of the visual magnocellular system.
基金supported in part by National Natural Science Foundation of China(No.81760597).
文摘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.
