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The European Journal of Neuroscience Sep 2020Despite evidence for a difference in total brain volume between dyslexic and good readers, no previous neuroimaging study examined differences in allometric scaling...
Despite evidence for a difference in total brain volume between dyslexic and good readers, no previous neuroimaging study examined differences in allometric scaling (i.e. differences in the relationship between regional and total brain volumes) between dyslexic and good readers. The present study aims to fill this gap by testing differences in allometric scaling and regional brain volume differences in dyslexic and good readers. Object-based morphometry analysis was used to determine grey and white matter volumes of the four lobes, the cerebellum and limbic structures in 130 dyslexic and 106 good readers aged 8-14 years. Data were collected across three countries (France, Poland and Germany). Three methodological approaches were used as follows: principal component analysis (PCA), linear regression and multiple-group confirmatory factor analysis (MGCFA). Difference in total brain volume between good and dyslexic readers was Cohen's d = 0.39. We found no difference in allometric scaling, nor in regional brain volume between dyslexic and good readers. Results of our three methodological approaches (PCA, linear regression and MGCFA) were consistent. This study provides evidence for total brain volume differences between dyslexic and control children, but no evidence for differences in the volumes of the four lobes, the cerebellum or limbic structures, once allometry is taken into account. It also finds no evidence for a difference in allometric relationships between the groups. We highlight the methodological interest of the MGCFA approach to investigate such research issues.
Topics: Brain Mapping; Child; Dyslexia; Germany; Humans; Magnetic Resonance Imaging; Neuroanatomy; Reading
PubMed: 31991019
DOI: 10.1111/ejn.14690 -
Dyslexia (Chichester, England) May 2021Despite difficulties in reading and writing, some research suggests that dyslexia may be related to higher levels of creativity. However, this pattern is not... (Meta-Analysis)
Meta-Analysis
Despite difficulties in reading and writing, some research suggests that dyslexia may be related to higher levels of creativity. However, this pattern is not consistently observed. The current research sought to ascertain whether individuals with clinically diagnosed dyslexia exhibit higher creativity than controls through a meta-analysis. Fourteen studies that assessed the creativity of 397 individuals with clinically diagnosed dyslexia and 453 controls were reviewed. Random-effects meta-analysis revealed an overall non-significant difference in creativity scores between those with dyslexia and controls. Additionally, method factors such as the type of creativity task and whether intelligence was controlled for, as well as sample-related factors such as gender, did not explain differences in the dyslexia-creativity relationship. Nonetheless, individuals with dyslexia significantly outperformed controls in creativity scores in adult samples, but not in younger child/adolescent samples. Overall, the current findings provide limited support for the idea that individuals with dyslexia are more creative, and that past evidence of this relationship may be limited to adult samples.
Topics: Adolescent; Adult; Child; Creativity; Dyslexia; Female; Humans; Male; Reading; Writing
PubMed: 33586314
DOI: 10.1002/dys.1677 -
NeuroImage Nov 2021Current views on the neural network subserving reading and its deficits in dyslexia rely largely on evidence derived from functional neuroimaging studies. However,... (Observational Study)
Observational Study
Current views on the neural network subserving reading and its deficits in dyslexia rely largely on evidence derived from functional neuroimaging studies. However, understanding the structural organization of reading and its aberrations in dyslexia requires a hodological approach, studies of which have not provided consistent findings. Here, we adopted a whole brain hodological approach and investigated relationships between structural white matter connectivity and reading skills and phonological processing in a cross-sectional study of 44 adults using individual local connectome matrix from diffusion MRI data. Moreover, we performed quantitative anisotropy aided differential tractography to uncover structural white matter anomalies in dyslexia (23 dyslexics and 21 matched controls) and their correlation to reading-related skills. The connectometry analyses indicated that reading skills and phonological processing were both associated with corpus callosum (tapetum), forceps major and minor, as well as cerebellum bilaterally. Furthermore, the left dorsal and right thalamic pathways were associated with phonological processing. Differential tractography analyses revealed structural white matter anomalies in dyslexics in the left ventral route and bilaterally in the dorsal route compared to the controls. Connectivity deficits were also observed in the corpus callosum, forceps major, vertical occipital fasciculus and corticostriatal and thalamic pathways. Altered structural connectivity in the observed differential tractography results correlated with poor reading skills and phonological processing. Using a hodological approach, the current study provides novel evidence for the extent of the reading-related connectome and its aberrations in dyslexia. The results conform current functional neuroanatomical models of reading and developmental dyslexia but provide novel network-level and tract-level evidence on structural connectivity anomalies in dyslexia, including the vertical occipital fasciculus.
Topics: Adult; Brain; Connectome; Cross-Sectional Studies; Dyslexia; Female; Humans; Magnetic Resonance Imaging; Male; Nerve Net; Reading; White Matter; Young Adult
PubMed: 34293464
DOI: 10.1016/j.neuroimage.2021.118411 -
Nutrients Jun 2023Neurodevelopmental disorders appear to be rising in prevalence, according to the recent Global Burden of Disease Study. This rise is likely to be multi-factorial, but... (Review)
Review
Neurodevelopmental disorders appear to be rising in prevalence, according to the recent Global Burden of Disease Study. This rise is likely to be multi-factorial, but the role of certain nutrients known to facilitate neurodevelopment should be considered. One possible contributing factor could be attributed to deficits in choline intake, particularly during key stages of neurodevelopment, which includes the first 1000 days of life and childhood. Choline, a key micronutrient, is crucial for optimal neurodevelopment and brain functioning of offspring. The present narrative review discusses the main research, describing the effect of choline in neurodevelopmental disorders, to better understand its role in the etiology and management of these disorders. In terms of findings, low choline intakes and reduced or altered choline status have been reported in relevant population subgroups: pregnancy (in utero), children with autism spectrum disorders, people with attention deficit hyperactivity disorder and those with dyslexia. In conclusion, an optimal choline provision may offer some neuronal protection in early life and help to mitigate some cognitive effects in later life attributed to neurodevelopmental conditions. Research indicates that choline may act as a modifiable risk factor for certain neurodevelopmental conditions. Ongoing research is needed to unravel the mechanisms and explanations.
Topics: Pregnancy; Child; Female; Humans; Attention Deficit Disorder with Hyperactivity; Neurodevelopmental Disorders; Autism Spectrum Disorder; Dyslexia
PubMed: 37447203
DOI: 10.3390/nu15132876 -
Dyslexia (Chichester, England) Aug 2021The primary aim of this study was to explore the overlaps between dyslexia and a range of neurodevelopmental disorders and problems (NDPs), specifically symptoms of...
The primary aim of this study was to explore the overlaps between dyslexia and a range of neurodevelopmental disorders and problems (NDPs), specifically symptoms of attention-deficit/hyperactivity disorder, autism spectrum disorder, atypical sensory perception and developmental coordination disorder. Capitalizing on a population-based sample of twins, secondary aims included estimating the heritability of dyslexia and reporting on the measurement characteristics of the scale used to assess dyslexia. A telephone interview regarding symptoms of dyslexia and other NDPs was conducted with parents of 1,688 nine-year-old twins. The prevalence and the heritability of dyslexia were estimated at 8 and 52%, respectively. The boy: girl ratio was 1.5:1. Results revealed that there was more than an eight-fold increase in (diagnostic proxy) NDPs prevalence in the dyslexia group as compared to typical readers. Quantitatively measured symptoms of inattention, oral language problems and atypical sensory perception significantly predicted dyslexia status in a multivariate analysis. By contrast, ASD-related inflexibility was inversely associated with dyslexia in the multivariate model. In sum, dyslexia often overlaps with other NDPs. The current study provides new knowledge supporting the position to move beyond isolated diagnostic categories into behavioural profiles of co-occurring problems when trying to understand the pattern of strengths and needs in individuals with dyslexia.
Topics: Attention Deficit Disorder with Hyperactivity; Autism Spectrum Disorder; Child; Comorbidity; Dyslexia; Female; Humans; Male; Parents; Prevalence
PubMed: 33759268
DOI: 10.1002/dys.1681 -
American Journal of Speech-language... Aug 2020Introduction The purpose of this study is to present three case studies of developmental dyslexia in dual-language learners (DLLs) and our assessment process. We... (Review)
Review
Introduction The purpose of this study is to present three case studies of developmental dyslexia in dual-language learners (DLLs) and our assessment process. We identify how phonological and orthographic deficits influence reading outcomes. We review the literature on theoretical models of bilingualism and reading models of developmental dyslexia to guide the assessment process through a multicomponential approach. We point out differences in the manifestation of dyslexia in more and less transparent writing systems. We suggest that reading instruction in Spanish can afford benefits to English-Spanish DLLs with developmental dyslexia. Method The study included three participants, two in fifth grade (10.3-11.7 years) and one in college (18.7 years). The assessment battery included reading nonwords and sight words (Test of Word Reading Efficiency); reading accuracy, fluency, and comprehension (Gray Oral Reading Tests-Fourth Edition); phonological awareness subtests (Comprehensive Test of Phonological Processing); and rapid automatized naming tests. A language and reading history interview was elicited from the mothers. In addition, we analyzed the participants' phonemic and word errors in reading. Results Our three participants showed core phonological deficits, with decreased performance in decoding nonwords and low accuracy in reading aloud. In spite of their reading and writing deficits, reading comprehension was within average levels for the three participants in this study. Conclusions We show the importance of assessing reading processes in students with a history of reading and writing problems. Our findings are based on three single case studies and are not generalizable. Our aim is to stimulate questions and research on dyslexia and the particular needs of DLLs.
Topics: Dyslexia; Humans; Language; Phonetics; Reading; Students
PubMed: 32750285
DOI: 10.1044/2020_AJSLP-19-00175 -
Multisensory Research Jan 2023The ability to efficiently combine information from different senses is an important perceptual process that underpins much of our daily activities. This process, known... (Review)
Review
The ability to efficiently combine information from different senses is an important perceptual process that underpins much of our daily activities. This process, known as multisensory integration, varies from individual to individual, and is affected by the ageing process, with impaired processing associated with age-related conditions, including balance difficulties, mild cognitive impairment and cognitive decline. Impaired multisensory perception has also been associated with a range of neurodevelopmental conditions, where novel intervention approaches are actively sought, for example dyslexia and autism. However, it remains unclear to what extent and how multisensory perception can be modified by training. This systematic review aims to evaluate the evidence that we can train multisensory perception in neurotypical adults. In all, 1521 studies were identified following a systematic search of the databases PubMed, Scopus, PsychInfo and Web of Science. Following screening for inclusion and exclusion criteria, 27 studies were chosen for inclusion. Study quality was assessed using the Methodological Index for Non-Randomised Studies (MINORS) tool and the Cochrane Risk of Bias tool 2.0 for Randomised Control Trials. We found considerable evidence that in-task feedback training using psychophysics protocols led to improved task performance. The generalisability of this training to other tasks of multisensory integration was inconclusive, with few studies and mixed findings reported. Promising findings from exercise-based training indicate physical activity protocols warrant further investigation as potential training avenues for improving multisensory integration. Future research directions should include trialling training protocols with clinical populations and other groups who would benefit from targeted training to improve inefficient multisensory integration.
Topics: Humans; Adult; Cognitive Dysfunction; Sensation; Task Performance and Analysis; Exercise; Dyslexia
PubMed: 36731526
DOI: 10.1163/22134808-bja10090 -
Journal of the International... Mar 2022According to the Procedural Deficit Hypothesis, abnormalities in corticostriatal pathways could account for the language-related deficits observed in developmental...
OBJECTIVES
According to the Procedural Deficit Hypothesis, abnormalities in corticostriatal pathways could account for the language-related deficits observed in developmental dyslexia. The same neural network has also been implicated in the ability to learn contingencies based on trial and error (i.e., reinforcement learning [RL]). On this basis, the present study tested the assumption that dyslexic individuals would be impaired in RL compared with neurotypicals in two different tasks.
METHODS
In a probabilistic selection task, participants were required to learn reinforcement contingencies based on probabilistic feedback. In an implicit transitive inference task, participants were also required to base their decisions on reinforcement histories, but feedback was deterministic and stimulus pairs were partially overlapping, such that participants were required to learn hierarchical relations.
RESULTS
Across tasks, results revealed that although the ability to learn from positive/negative feedback did not differ between the two groups, the learning of reinforcement contingencies was poorer in the dyslexia group compared with the neurotypicals group. Furthermore, in novel test pairs where previously learned information was presented in new combinations, dyslexic individuals performed similarly to neurotypicals.
CONCLUSIONS
Taken together, these results suggest that learning of reinforcement contingencies occurs less robustly in individuals with developmental dyslexia. Inferences for the neuro-cognitive mechanisms of developmental dyslexia are discussed.
Topics: Dyslexia; Humans
PubMed: 33823958
DOI: 10.1017/S1355617721000266 -
Journal of Child Psychology and... May 2021This paper discusses research on reading disorders during the period since their classification within the overarching category of neurodevelopmental disorders (Journal... (Review)
Review
This paper discusses research on reading disorders during the period since their classification within the overarching category of neurodevelopmental disorders (Journal of Child Psychology and Psychiatry, 53, 2012, 593). Following a review of the predictors of learning to read across languages, and the role of language skills as critical foundations for literacy, profiles of reading disorders are discussed and putative causal risk factors at the cognitive, biological, and environmental levels of explanation considered. Reading disorders are highly heritable and highly comorbid with disorders of language, attention, and other learning disorders, notably mathematics disorders. The home literacy environment, reflecting gene-environment correlation, is one of several factors that promote reading development and highlight an important target for intervention. The multiple deficit view of dyslexia (Cognition, 101, 2006, 385) suggests that risks accumulate to a diagnostic threshold although categorical diagnoses tend to be unstable. Implications for assessment and intervention are discussed.
Topics: Child; Comprehension; Dyslexia; Humans; Language; Language Development Disorders; Literacy
PubMed: 32956509
DOI: 10.1111/jcpp.13324 -
Neuroscience and Biobehavioral Reviews Jan 2022Behavioral research supports the efficacy of intervention for reading disability, but the brain mechanisms underlying improvement in reading are not well understood.... (Meta-Analysis)
Meta-Analysis Review
Behavioral research supports the efficacy of intervention for reading disability, but the brain mechanisms underlying improvement in reading are not well understood. Here, we review 39 neuroimaging studies of reading intervention to characterize links between reading improvement and changes in the brain. We report evidence of changes in activation, connectivity, and structure within the reading network, and right hemisphere, frontal and sub-cortical regions. Our meta-analysis of changes in brain activation from pre- to post- reading intervention in eight studies did not yield any significant effects. Methodological heterogeneity among studies may contribute to the lack of significant meta-analytic findings. Based on our qualitative synthesis, we propose that brain changes in response to intervention should be considered in terms of interactions among distributed cognitive, linguistic and sensory systems, rather than via a "normalized" vs. "compensatory" dichotomy. Further empirical research is needed to identify effects of moderating factors such as features of intervention programs, neuroimaging tasks, and individual differences among participants.
Topics: Brain; Brain Mapping; Dyslexia; Humans; Magnetic Resonance Imaging; Neuronal Plasticity
PubMed: 34856223
DOI: 10.1016/j.neubiorev.2021.11.011