Dyslexia is a specific learning disability that is neurobiological in origin.It is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities.Teachers may no...Dyslexia is a specific learning disability that is neurobiological in origin.It is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities.Teachers may not be very sure about the definition of dyslexia and generally struggle to tell the difference between dyslexic learners and slow learners.Developing the DyAwI may provide an important psychometric assessment tool in determining the awareness level of the teacher and being able to make this distinction.A descriptive,explorative design was used in this study.The study consisted of two main phases.In the first phase,in order to develop the instrument,a literature review and a pilot study on 20 primary school teachers were carried out,and in line with expert opinions,the content validity index was calculated.In the second stage,exploratory and confirmatory factor analyses were carried out to identify the construct validity and reliability.The study included 182 primary school teachers for the second stage.The KMO and Bartlett test values,which determine the suitability of DyAwI for factor analysis,were found to be 0.77 and 0.000,respectively.The overall Cronbach’s alpha value of DyAwI was 0.75.As a result of the assessment of its construct validity,the scale consisted of 2 factors and 14 items.The findings of the study show that the tool is reliable and sufficient.The instrument is easy to understand,and this tool can determine the dyslexia awareness levels of teachers.DyAwI could promote teachers’awareness of dyslexia and support the early identification of primary school students with dyslexia.It is believed that,thanks to the data obtained from the instrument,teachers will be able to decide on an educational assessment of a student with reading difficulties more quickly.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
Over the last two decades, the hypothesis of a magnocellular deficit in dyslexia has raised considerable interest and controversy. Using an electrophysiological procedure (visual evoked potentials, VEP), we compared m...Over the last two decades, the hypothesis of a magnocellular deficit in dyslexia has raised considerable interest and controversy. Using an electrophysiological procedure (visual evoked potentials, VEP), we compared magnocellular and parvocellular contrast and spatial frequency-response functions between phonological dyslexics (n = 16) and a typical reading group (n = 12) matched for age and socioeconomic background. No significant differences were found between the two groups in the amplitude of the VEP components associated with either magnocellular or parvocellular responses. However, topographic analyses revealed a group difference in the distribution of amplitude in the right frontal and left temporal regions, which appeared to be underactivated in dyslexics. These results suggest a deficit in the higher-level cortical regions involved in phonological and/or linguistic processing, and calls into question the notion of a magnocellular involvement in dyslexia.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
This study investigated the effect of a visual memory training program on Chinese handwriting performance among primary school students with dyslexia in Hong Kong. Eight students of Grade 2 to 3 who were diagnosed wit...This study investigated the effect of a visual memory training program on Chinese handwriting performance among primary school students with dyslexia in Hong Kong. Eight students of Grade 2 to 3 who were diagnosed with dyslexia were recruited. All participants received six sessions of training, which composed of 30-minute computerized game-based visual memory training and 30-minute Chinese character segmentation training. Visual perceptual skills and Chinese handwriting performance were assessed before and after the training, as well as three weeks after training using the Test of Visual Perceptual Skills (3rd edition) (TVPS-3) and the Chinese Handwriting Analysis System (CHAS). In comparing the pre- and post-training results, paired t-tests revealed significant improvements in visual memory skills, as well as handwriting speed, pause time and pen pressure after the training. There was no significant improvement in handwriting accuracy or legibility. The improved visual memory and handwriting performance did not show a significant drop at the follow-up assessments. This study showed promising results on a structured program to improve the Chinese handwriting performance, mainly in speed, of primary school children. The improvements appeared to be well-sustained after the training program. There is a need to further study the long-term effect of the program through a randomized controlled trial study.展开更多
Aim:to analyze the significance of RTI Tier 2 metaphonological and alphabetic principle program for Brazilian schoolchildren at risk for dyslexia.Methods:a bibliographic review was carried out in the Scielo and Pubmed...Aim:to analyze the significance of RTI Tier 2 metaphonological and alphabetic principle program for Brazilian schoolchildren at risk for dyslexia.Methods:a bibliographic review was carried out in the Scielo and Pubmed databases using the descriptors“intervention studies”,“reading”,“dyslexia”,and“learning”in Portuguese and English for the elaboration of RTI Tier 2 metaphonological and alphabetic principle program for schoolchildren at risk for dyslexia.The program was designed based on the selection of strategies for metaphonological skills,knowledge of the alphabet,and grapheme-phoneme correspondence described in national and international literature.Linguistic stimuli(real words)and visual stimuli(pictures)were selected to be used in the intervention program tasks.These stimuli were selected from a word bank according to length,regularity,and frequency.The intervention program designed was composed of the following skills:letter-sound knowledge,syllable knowledge,syllabic segmentation,phonemic segmentation,syllabic addition,phonemic addition,syllabic subtraction,phonemic subtraction,syllabic substitution,phonemic substitution,syllabic combination,and phonemic combination.The program was structured with collective strategies and was applied in small groups of four to five schoolchildren aged six years and 11 months to seven years and 11 months in 50-minute sessions.Results:The results revealed that there was a change in the response pattern,showing better performance in the skills of the Early Identification of Reading Problems Protocol,demonstrating significance and positive change in post-testing situations when compared to pre-testing.Conclusion:the program developed in this study proved to be effective and,in this way,it can be used as an intervention instrument based on scientific evidence that helps in the acquisition of skills necessary for the development of reading.展开更多
Background:Proficient literacy skills and reading comprehension are crucial skills for participation and success in everyday life.One group that regularly falls short in demonstrating good reading skills are people wi...Background:Proficient literacy skills and reading comprehension are crucial skills for participation and success in everyday life.One group that regularly falls short in demonstrating good reading skills are people with dyslexia.This group suffers from a range of visual deficits including the pattern of ocular movements,and distorted,blurred and reversed(or mirrored)vision of letters during reading.However,only recently designers started to develop affordable and easily implementable remedies that are supposed to reduce the visual symptoms of dyslexia such as specific dyslexia fonts.These fonts incorporate properties aimed at improving the visual and behavioural reading performance of people with dyslexia by using larger intra-and inter-word whitespace,unique letter shapes and no serifs.To date,empirical evidence about the efficacy of these fonts is contradictory,and their effects on adult dyslexics’eye movements and cognitive processing during longer reading tasks remains elusive.Methods:To bridge this gap,we measured the eye movements of adults with and without dyslexia during the reading of a set of standardised texts from the international reading speed texts(IReST;Trauzettel-Klosinski&Dietz,2012)reading battery coupled with validated comprehension questions.These texts and questions were presented either in the traditional font Times New Roman or the specific dyslexia font OpenDyslexic.Results:Here,we found that OpenDyslexic led to improvements in reading comprehension in dyslexics and non-dyslexics.These improvements were larger for dyslexics.Contrarily,participants’reading speed was unaffected by OpenDyslexic.Our eye-tracking data showed that OpenDyslexic resulted in a higher number of eye movements,reduced visual search intensity,and longer median fixation duration across participants.Particularly,median fixation duration,as a measure of cognitive load,was predictive of reading comprehension across groups.Among dyslexics,OpenDyslexic yielded increases in visual search intensity and visual ease in the form of decreases in median fixation duration and fixation to saccade ratio as well as a smaller number of falsely programmed forward saccades.Conclusions:Our findings illustrate that OpenDyslexic results in a different visual reading strategy.These findings provide empirical evidence for the efficacy of OpenDyslexic in longer standardised texts and suggest its use in everyday documents,education materials,and online sources.展开更多
Background:Aim of the study is to provide an operational definition of“visual dyslexia”referred to a particular subgroup of dyslexics characterized by x,y anisotropic perception of the visual space,or unstable ocula...Background:Aim of the study is to provide an operational definition of“visual dyslexia”referred to a particular subgroup of dyslexics characterized by x,y anisotropic perception of the visual space,or unstable ocular dominance,or abnormal binocular interaction,and who benefit from increased interletter spacing.The working hypothesis of this investigation is that in dyslexic children who show the abovementioned alterations the correlation between reading rate and interletter spacing is a marker of visual involvement,and supports a causal role of these visual-perceptive alterations in their reading problems.Methods:Based on the results obtained by three psychophysical tests devised on purpose,a group of 193 school-age disabled readers with normal visual acuity and no significant co-morbidities has been classified into four different classes:non-visual-perceptive sample,anisotropic sample(AS),abnormal binocular interaction sample and unstable dominance sample(UDS).To test for the working hypothesis,the absence of the visual marker has been verified in the non-visual-perceptive sample,and its presence has then been investigated in the remaining classes.Results:The non-visual-perceptive class was negative to the visual marker.In the other classes the average reading rate of words and non-words improved as a function of the distance between characters(AS:R2:0.51 and 0.43,P=0.01 and 0.02 respectively;abnormal binocular interaction sample:R2:0.47 and R2:0.57,P=0.02 and 0.007 respectively;unstable dominance:R2:0.43,P=0.02 at non-words).Yet,individual analysis revealed that the marker was present in no more than 23%of subjects with increased anisotropy,in 50%of unstable dominants,and in only 12%of patients with abnormal interocular inhibition.Conclusions:Even if on a population scale this line of investigation seems able to provide an operational definition of“visual dyslexia”,the individual detection of the“visual dyslexics”requires methodological improvement.展开更多
Background:Individuals with dyslexia present with a variety of reading related deficits including text comprehension,reading speed and word encoding.While previous literature addresses individual components of group d...Background:Individuals with dyslexia present with a variety of reading related deficits including text comprehension,reading speed and word encoding.While previous literature addresses individual components of group differences,the present study compares individuals with dyslexia and normal readers on a variety of eye tracking components,as well as behavioural reading measures.The applied nature of this research allows for a comprehensive understanding of how individuals with dyslexia perceptually encode and process written texts.Using type font(i.e.,Times New Roman vs.OpenDyslexic;a font created to elevate visually specific characteristics of dyslexia)as a mediator,we investigated the group differences in eye movement patterns,text comprehension and reading speed between normal readers and individuals with dyslexia when reading standardized and validated texts designed for a grade six reading comprehension level.Methods:Our 73 participants included 38 normal reading controls and 35 individuals with dyslexia.Participants were administered the symbol search and coding subtests of The Wechsler Adult Scale of Intelligence.Participants then read ten texts from the International Reading Speed Texts:five texts in Times New Roman and five in OpenDyslexic,while binocular eye movements were recorded using a SR Research Eyelink 1000.Results:We found that irrespective of font type,when compared to controls,individuals with dyslexia demonstrated increased re-reading of texts[i.e.,regressions:CI(−0.99,−0.66),Hedges’s gs=−0.83]and number of saccades per trial[CI(−1.42,−1.08),gs=−1.25]as well as increased median fixation duration[CI(−1.15,−0.82),gs=−0.98].The control group had increased reading speed[words per minute:CI(1.48,1.84),gs=1.65],visited less interest areas[CI(−1.48,−1.13),gs=−1.31],and had fewer directional deviations from the horizontal-axis[CI(−0.49,−0.18),gs=−0.33].We found an interaction between text comprehension and font type,with both groups having improved performance with OpenDyslexic.However,results did not show a main effect of group with respect to text comprehension.Conclusions:The lack of group differences in text comprehension illustrates that high-functioning individuals with dyslexia are able to comprehend these elementary level texts,irrespective of font type.However,the erratic nature of their eye movements combined with a slow reading speed suggest that individuals with dyslexia read texts in a different manner;achieving the same understanding as normal readers.Our results suggest that reading speed differences act as compensatory methods in our sample of individuals with dyslexia.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 the ...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
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
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 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 bas...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.展开更多
Nowadays,several noninvasive neuroimaging techniques,including transcranial magnetic stimulation(TMS),exist.The working mechanism behind TMS is a rapidly changing magnetic field that generates an electric current via ...Nowadays,several noninvasive neuroimaging techniques,including transcranial magnetic stimulation(TMS),exist.The working mechanism behind TMS is a rapidly changing magnetic field that generates an electric current via electromagnetic induction.When the coil is placed on the scalp,the magnetic field generates a physiological reaction in the underlying neural tissue.The TMS-induced change in the participant’s behavior is used by researchers to investigate the causal relations between specific brain areas and cognitive functions such as language.A variant of TMS has been developed,which is called rapid-rate TMS(rTMS).In this review,three databases(Medline,Educational Resources Information Center,and Scopus)were searched for rTMS studies on normal reading and dyslexia with a cut-off date of October 31,2014.rTMS was found to be a valuable tool for investigating questions related to reading research,both on the word and the sentence level.Moreover,it can be successfully used in research on dyslexia.Recently,(high-frequency)rTMS has been used as a“clinical”intervention technique for treating dyslexia and for improving reading performance by exciting underactive reading pathways in the brain.Finally,we end the paper with a discussion of future directions in the field of rTMS research and dyslexia,for instance,the promising prospect of combining TMS with simultaneous electroencephalographic imaging.展开更多
文摘Dyslexia is a specific learning disability that is neurobiological in origin.It is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities.Teachers may not be very sure about the definition of dyslexia and generally struggle to tell the difference between dyslexic learners and slow learners.Developing the DyAwI may provide an important psychometric assessment tool in determining the awareness level of the teacher and being able to make this distinction.A descriptive,explorative design was used in this study.The study consisted of two main phases.In the first phase,in order to develop the instrument,a literature review and a pilot study on 20 primary school teachers were carried out,and in line with expert opinions,the content validity index was calculated.In the second stage,exploratory and confirmatory factor analyses were carried out to identify the construct validity and reliability.The study included 182 primary school teachers for the second stage.The KMO and Bartlett test values,which determine the suitability of DyAwI for factor analysis,were found to be 0.77 and 0.000,respectively.The overall Cronbach’s alpha value of DyAwI was 0.75.As a result of the assessment of its construct validity,the scale consisted of 2 factors and 14 items.The findings of the study show that the tool is reliable and sufficient.The instrument is easy to understand,and this tool can determine the dyslexia awareness levels of teachers.DyAwI could promote teachers’awareness of dyslexia and support the early identification of primary school students with dyslexia.It is believed that,thanks to the data obtained from the instrument,teachers will be able to decide on an educational assessment of a student with reading difficulties more quickly.
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.
文摘Over the last two decades, the hypothesis of a magnocellular deficit in dyslexia has raised considerable interest and controversy. Using an electrophysiological procedure (visual evoked potentials, VEP), we compared magnocellular and parvocellular contrast and spatial frequency-response functions between phonological dyslexics (n = 16) and a typical reading group (n = 12) matched for age and socioeconomic background. No significant differences were found between the two groups in the amplitude of the VEP components associated with either magnocellular or parvocellular responses. However, topographic analyses revealed a group difference in the distribution of amplitude in the right frontal and left temporal regions, which appeared to be underactivated in dyslexics. These results suggest a deficit in the higher-level cortical regions involved in phonological and/or linguistic processing, and calls into question the notion of a magnocellular involvement in dyslexia.
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.
文摘This study investigated the effect of a visual memory training program on Chinese handwriting performance among primary school students with dyslexia in Hong Kong. Eight students of Grade 2 to 3 who were diagnosed with dyslexia were recruited. All participants received six sessions of training, which composed of 30-minute computerized game-based visual memory training and 30-minute Chinese character segmentation training. Visual perceptual skills and Chinese handwriting performance were assessed before and after the training, as well as three weeks after training using the Test of Visual Perceptual Skills (3rd edition) (TVPS-3) and the Chinese Handwriting Analysis System (CHAS). In comparing the pre- and post-training results, paired t-tests revealed significant improvements in visual memory skills, as well as handwriting speed, pause time and pen pressure after the training. There was no significant improvement in handwriting accuracy or legibility. The improved visual memory and handwriting performance did not show a significant drop at the follow-up assessments. This study showed promising results on a structured program to improve the Chinese handwriting performance, mainly in speed, of primary school children. The improvements appeared to be well-sustained after the training program. There is a need to further study the long-term effect of the program through a randomized controlled trial study.
基金National Council for Scientific and Technological Development(CNPq)and Coordination for the Improvement of Higher Education Personnel(CAPES).
文摘Aim:to analyze the significance of RTI Tier 2 metaphonological and alphabetic principle program for Brazilian schoolchildren at risk for dyslexia.Methods:a bibliographic review was carried out in the Scielo and Pubmed databases using the descriptors“intervention studies”,“reading”,“dyslexia”,and“learning”in Portuguese and English for the elaboration of RTI Tier 2 metaphonological and alphabetic principle program for schoolchildren at risk for dyslexia.The program was designed based on the selection of strategies for metaphonological skills,knowledge of the alphabet,and grapheme-phoneme correspondence described in national and international literature.Linguistic stimuli(real words)and visual stimuli(pictures)were selected to be used in the intervention program tasks.These stimuli were selected from a word bank according to length,regularity,and frequency.The intervention program designed was composed of the following skills:letter-sound knowledge,syllable knowledge,syllabic segmentation,phonemic segmentation,syllabic addition,phonemic addition,syllabic subtraction,phonemic subtraction,syllabic substitution,phonemic substitution,syllabic combination,and phonemic combination.The program was structured with collective strategies and was applied in small groups of four to five schoolchildren aged six years and 11 months to seven years and 11 months in 50-minute sessions.Results:The results revealed that there was a change in the response pattern,showing better performance in the skills of the Early Identification of Reading Problems Protocol,demonstrating significance and positive change in post-testing situations when compared to pre-testing.Conclusion:the program developed in this study proved to be effective and,in this way,it can be used as an intervention instrument based on scientific evidence that helps in the acquisition of skills necessary for the development of reading.
文摘Background:Proficient literacy skills and reading comprehension are crucial skills for participation and success in everyday life.One group that regularly falls short in demonstrating good reading skills are people with dyslexia.This group suffers from a range of visual deficits including the pattern of ocular movements,and distorted,blurred and reversed(or mirrored)vision of letters during reading.However,only recently designers started to develop affordable and easily implementable remedies that are supposed to reduce the visual symptoms of dyslexia such as specific dyslexia fonts.These fonts incorporate properties aimed at improving the visual and behavioural reading performance of people with dyslexia by using larger intra-and inter-word whitespace,unique letter shapes and no serifs.To date,empirical evidence about the efficacy of these fonts is contradictory,and their effects on adult dyslexics’eye movements and cognitive processing during longer reading tasks remains elusive.Methods:To bridge this gap,we measured the eye movements of adults with and without dyslexia during the reading of a set of standardised texts from the international reading speed texts(IReST;Trauzettel-Klosinski&Dietz,2012)reading battery coupled with validated comprehension questions.These texts and questions were presented either in the traditional font Times New Roman or the specific dyslexia font OpenDyslexic.Results:Here,we found that OpenDyslexic led to improvements in reading comprehension in dyslexics and non-dyslexics.These improvements were larger for dyslexics.Contrarily,participants’reading speed was unaffected by OpenDyslexic.Our eye-tracking data showed that OpenDyslexic resulted in a higher number of eye movements,reduced visual search intensity,and longer median fixation duration across participants.Particularly,median fixation duration,as a measure of cognitive load,was predictive of reading comprehension across groups.Among dyslexics,OpenDyslexic yielded increases in visual search intensity and visual ease in the form of decreases in median fixation duration and fixation to saccade ratio as well as a smaller number of falsely programmed forward saccades.Conclusions:Our findings illustrate that OpenDyslexic results in a different visual reading strategy.These findings provide empirical evidence for the efficacy of OpenDyslexic in longer standardised texts and suggest its use in everyday documents,education materials,and online sources.
文摘Background:Aim of the study is to provide an operational definition of“visual dyslexia”referred to a particular subgroup of dyslexics characterized by x,y anisotropic perception of the visual space,or unstable ocular dominance,or abnormal binocular interaction,and who benefit from increased interletter spacing.The working hypothesis of this investigation is that in dyslexic children who show the abovementioned alterations the correlation between reading rate and interletter spacing is a marker of visual involvement,and supports a causal role of these visual-perceptive alterations in their reading problems.Methods:Based on the results obtained by three psychophysical tests devised on purpose,a group of 193 school-age disabled readers with normal visual acuity and no significant co-morbidities has been classified into four different classes:non-visual-perceptive sample,anisotropic sample(AS),abnormal binocular interaction sample and unstable dominance sample(UDS).To test for the working hypothesis,the absence of the visual marker has been verified in the non-visual-perceptive sample,and its presence has then been investigated in the remaining classes.Results:The non-visual-perceptive class was negative to the visual marker.In the other classes the average reading rate of words and non-words improved as a function of the distance between characters(AS:R2:0.51 and 0.43,P=0.01 and 0.02 respectively;abnormal binocular interaction sample:R2:0.47 and R2:0.57,P=0.02 and 0.007 respectively;unstable dominance:R2:0.43,P=0.02 at non-words).Yet,individual analysis revealed that the marker was present in no more than 23%of subjects with increased anisotropy,in 50%of unstable dominants,and in only 12%of patients with abnormal interocular inhibition.Conclusions:Even if on a population scale this line of investigation seems able to provide an operational definition of“visual dyslexia”,the individual detection of the“visual dyslexics”requires methodological improvement.
文摘Background:Individuals with dyslexia present with a variety of reading related deficits including text comprehension,reading speed and word encoding.While previous literature addresses individual components of group differences,the present study compares individuals with dyslexia and normal readers on a variety of eye tracking components,as well as behavioural reading measures.The applied nature of this research allows for a comprehensive understanding of how individuals with dyslexia perceptually encode and process written texts.Using type font(i.e.,Times New Roman vs.OpenDyslexic;a font created to elevate visually specific characteristics of dyslexia)as a mediator,we investigated the group differences in eye movement patterns,text comprehension and reading speed between normal readers and individuals with dyslexia when reading standardized and validated texts designed for a grade six reading comprehension level.Methods:Our 73 participants included 38 normal reading controls and 35 individuals with dyslexia.Participants were administered the symbol search and coding subtests of The Wechsler Adult Scale of Intelligence.Participants then read ten texts from the International Reading Speed Texts:five texts in Times New Roman and five in OpenDyslexic,while binocular eye movements were recorded using a SR Research Eyelink 1000.Results:We found that irrespective of font type,when compared to controls,individuals with dyslexia demonstrated increased re-reading of texts[i.e.,regressions:CI(−0.99,−0.66),Hedges’s gs=−0.83]and number of saccades per trial[CI(−1.42,−1.08),gs=−1.25]as well as increased median fixation duration[CI(−1.15,−0.82),gs=−0.98].The control group had increased reading speed[words per minute:CI(1.48,1.84),gs=1.65],visited less interest areas[CI(−1.48,−1.13),gs=−1.31],and had fewer directional deviations from the horizontal-axis[CI(−0.49,−0.18),gs=−0.33].We found an interaction between text comprehension and font type,with both groups having improved performance with OpenDyslexic.However,results did not show a main effect of group with respect to text comprehension.Conclusions:The lack of group differences in text comprehension illustrates that high-functioning individuals with dyslexia are able to comprehend these elementary level texts,irrespective of font type.However,the erratic nature of their eye movements combined with a slow reading speed suggest that individuals with dyslexia read texts in a different manner;achieving the same understanding as normal readers.Our results suggest that reading speed differences act as compensatory methods in our sample of individuals with dyslexia.
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,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.
基金supported by the Key-Area Research and Development Program of Guangdong Province(No.2019B030335001)the National Science Foundation of China(No.20&ZD296,No.32171063)+1 种基金the Science and Technology Project of Guangzhou City(No.201804020085)Shanghai Clinical Research Center for Mental Health(No.19MC1911100).
文摘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.
文摘Nowadays,several noninvasive neuroimaging techniques,including transcranial magnetic stimulation(TMS),exist.The working mechanism behind TMS is a rapidly changing magnetic field that generates an electric current via electromagnetic induction.When the coil is placed on the scalp,the magnetic field generates a physiological reaction in the underlying neural tissue.The TMS-induced change in the participant’s behavior is used by researchers to investigate the causal relations between specific brain areas and cognitive functions such as language.A variant of TMS has been developed,which is called rapid-rate TMS(rTMS).In this review,three databases(Medline,Educational Resources Information Center,and Scopus)were searched for rTMS studies on normal reading and dyslexia with a cut-off date of October 31,2014.rTMS was found to be a valuable tool for investigating questions related to reading research,both on the word and the sentence level.Moreover,it can be successfully used in research on dyslexia.Recently,(high-frequency)rTMS has been used as a“clinical”intervention technique for treating dyslexia and for improving reading performance by exciting underactive reading pathways in the brain.Finally,we end the paper with a discussion of future directions in the field of rTMS research and dyslexia,for instance,the promising prospect of combining TMS with simultaneous electroencephalographic imaging.
