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Journal of Learning Disabilities 2013The primary goal of this review is to highlight current research and theories describing the neurobiological basis of math (MD), reading (RD), and comorbid math and... (Review)
Review
The primary goal of this review is to highlight current research and theories describing the neurobiological basis of math (MD), reading (RD), and comorbid math and reading disability (MD+RD). We first describe the unique brain and cognitive processes involved in acquisition of math and reading skills, emphasizing similarities and differences in each domain. Next we review functional imaging studies of MD and RD in children, integrating relevant theories from experimental psychology and cognitive neuroscience to characterize the functional neuroanatomy of cognitive dysfunction in MD and RD. We then review recent research on the anatomical correlates of MD and RD. Converging evidence from morphometry and tractography studies are presented to highlight distinct patterns of white matter pathways which are disrupted in MD and RD. Finally, we examine how the intersection of MD and RD provides a unique opportunity to clarify the unique and shared brain systems which adversely impact learning and skill acquisition in MD and RD, and point out important areas for future work on comorbid learning disabilities.
Topics: Brain; Comorbidity; Dyscalculia; Dyslexia; Humans
PubMed: 23572008
DOI: 10.1177/0022219413483174 -
Neurocase Oct 2022Diagnostic criteria for dyslexia describe specific reading difficulties, and single-deficit models, including the phonological deficit theory, have prevailed. Children...
Diagnostic criteria for dyslexia describe specific reading difficulties, and single-deficit models, including the phonological deficit theory, have prevailed. Children seeking diagnosis, however, do not always show phonological deficits, and may present with strengths and challenges beyond reading. Through extensive neurological, neuropsychological, and academic evaluation, we describe four children with visuospatial, socio-emotional, and attention impairments and spared phonology, alongside long-standing reading difficulties. Diffusion tensor imaging revealed white matter alterations in inferior longitudinal, uncinate, and superior longitudinal fasciculi versus neurotypical children. Findings emphasize that difficulties may extend beyond reading in dyslexia and underscore the value of deep phenotyping in learning disabilities.
Topics: Child; Humans; Diffusion Tensor Imaging; Phonetics; Dyslexia; Reading; White Matter
PubMed: 36450280
DOI: 10.1080/13554794.2022.2145905 -
Clinical Neurophysiology : Official... May 2022We investigated early maturation of the infant mismatch response MMR, including mismatch negativity (MMN), positive MMR (P-MMR), and late discriminative negativity...
OBJECTIVE
We investigated early maturation of the infant mismatch response MMR, including mismatch negativity (MMN), positive MMR (P-MMR), and late discriminative negativity (LDN), indexing auditory discrimination abilities, and the influence of familial developmental dyslexia risk.
METHODS
We recorded MMRs to vowel, duration, and frequency deviants in pseudo-words at 0, 6, and 28 months and compared MMRs in subgroups with vs. without dyslexia risk, in a sample over-represented by risk infants.
RESULTS
Neonatal MMN to the duration deviant became larger and earlier by 28 months; MMN was elicited by more deviants only at 28 months. The P-MMR was predominant in infancy; its amplitude increased by 6 and decreased by 28 months; latency decreased with increasing age. An LDN emerged by 6 months and became larger and later by 28 months. Dyslexia risk affected MMRs and their maturation.
CONCLUSIONS
MMRs demonstrate an expected maturational pattern with 2-3 peaks by 28 months. The effects of dyslexia risk are prominent but not always as expected.
SIGNIFICANCE
This large-scale longitudinal study shows MMR maturation with three age groups and three deviants. Results illuminate MMR's relation to the adult responses, and hence their cognitive underpinnings, and help in identifying typical/atypical auditory development in early childhood.
Topics: Acoustic Stimulation; Adult; Child, Preschool; Dyslexia; Electroencephalography; Evoked Potentials, Auditory; Humans; Infant; Infant, Newborn; Longitudinal Studies; Speech Perception
PubMed: 35358758
DOI: 10.1016/j.clinph.2022.03.005 -
Cerebral Cortex (New York, N.Y. : 1991) Mar 2018Developmental dyslexia is frequently associated with atypical brain structure and function within regions of the left hemisphere reading network. To date, few studies...
Developmental dyslexia is frequently associated with atypical brain structure and function within regions of the left hemisphere reading network. To date, few studies have employed surface-based techniques to evaluate cortical thickness and local gyrification in dyslexia. Of the existing cortical thickness studies in children, many are limited by small sample size, variability in dyslexia identification, and the recruitment of prereaders who may or may not develop reading impairment. Further, no known study has assessed local gyrification index (LGI) in dyslexia, which may serve as a sensitive indicator of atypical neurodevelopment. In this study, children with dyslexia (n = 31) and typically decoding peers (n = 45) underwent structural magnetic resonance imaging to assess whole-brain vertex-wise cortical thickness and LGI. Children with dyslexia demonstrated reduced cortical thickness compared with controls within previously identified reading areas including bilateral occipitotemporal and occipitoparietal regions. Compared with controls, children with dyslexia also showed increased gyrification in left occipitotemporal and right superior frontal cortices. The convergence of thinner and more gyrified cortex within the left occipitotemporal region among children with dyslexia may reflect its early temporal role in processing word forms, and highlights the importance of the ventral stream for successful word reading.
Topics: Adolescent; Analysis of Variance; Brain Mapping; Cerebral Cortex; Child; Dyslexia; Female; Functional Laterality; Humans; Image Processing, Computer-Assisted; Intelligence; Magnetic Resonance Imaging; Male; Reading
PubMed: 28108497
DOI: 10.1093/cercor/bhx001 -
Molecular Genetics and Metabolism Nov 2013Dyslexia is a common pediatric disorder that affects 5-17% of schoolchildren in the United States. It is marked by unexpected difficulties in fluent reading despite... (Review)
Review
Dyslexia is a common pediatric disorder that affects 5-17% of schoolchildren in the United States. It is marked by unexpected difficulties in fluent reading despite adequate intelligence, opportunity, and instruction. Classically, neuropsychologists have studied dyslexia using a variety of neurocognitive batteries to gain insight into the specific deficits and impairments in affected children. Since dyslexia is a complex genetic trait with high heritability, analyses conditioned on performance on these neurocognitive batteries have been used to try to identify associated genes. This has led to some successes in identifying contributing genes, although much of the heritability remains unexplained. Additionally, the lack of relevant human brain tissue for analysis and the challenges of modeling a uniquely human trait in animals are barriers to advancing our knowledge of the underlying pathophysiology. In vivo imaging technologies, however, present new opportunities to examine dyslexia and reading skills in a clearly relevant context in human subjects. Recent investigations have started to integrate these imaging data with genetic data in attempts to gain a more complete and complex understanding of reading processes. In addition to bridging the gap from genetic risk variant to a discernible neuroimaging phenotype and ultimately to the clinical impairments in reading performance, the use of neuroimaging phenotypes will reveal novel risk genes and variants. In this article, we briefly discuss the genetic and imaging investigations and take an in-depth look at the recent imaging-genetics investigations of dyslexia.
Topics: Brain; Dyslexia; Genetic Predisposition to Disease; Genetic Variation; Humans; Neuroimaging
PubMed: 23916419
DOI: 10.1016/j.ymgme.2013.07.001 -
ELife Sep 2021Brain abnormalities in the reading network have been repeatedly reported in individuals with developmental dyslexia (DD); however, it is still not totally understood... (Meta-Analysis)
Meta-Analysis
Brain abnormalities in the reading network have been repeatedly reported in individuals with developmental dyslexia (DD); however, it is still not totally understood where the structural and functional abnormalities are consistent/inconsistent across languages. In the current multimodal meta-analysis, we found convergent structural and functional alterations in the left superior temporal gyrus across languages, suggesting a neural signature of DD. We found greater reduction in grey matter volume and brain activation in the left inferior frontal gyrus in morpho-syllabic languages (e.g. Chinese) than in alphabetic languages, and greater reduction in brain activation in the left middle temporal gyrus and fusiform gyrus in alphabetic languages than in morpho-syllabic languages. These language differences are explained as consequences of being DD while learning a specific language. In addition, we also found brain regions that showed increased grey matter volume and brain activation, presumably suggesting compensations and brain regions that showed inconsistent alterations in brain structure and function. Our study provides important insights about the etiology of DD from a cross-linguistic perspective with considerations of consistency/inconsistency between structural and functional alterations.
Topics: Adolescent; Adult; Brain; Brain Mapping; Child; Dyslexia; Female; Humans; Language; Learning; Magnetic Resonance Imaging; Male; Young Adult
PubMed: 34569931
DOI: 10.7554/eLife.69523 -
Pediatric Rehabilitation 2006Remarkably few research articles on the treatment of developmental dyslexia were published during the last 25 years. Some treatment research arose from the temporal... (Review)
Review
Remarkably few research articles on the treatment of developmental dyslexia were published during the last 25 years. Some treatment research arose from the temporal processing theory, some from the phonological deficit hypothesis and some more from the balance model of learning to read and dyslexia. Within the framework of that model, this article reviews the aetiology of dyslexia sub-types, the neuropsychological rationale for treatment, the treatment techniques and the outcomes of treatment research. The possible mechanisms underlying the effects of treatment are discussed.
Topics: Child; Dyslexia; Humans; Learning; Reading
PubMed: 16352500
DOI: 10.1080/13638490500065392 -
Annals of Dyslexia Jul 2023Dyslexia is one of the most studied learning disorders. Despite this, its biological basis and main causes are still not fully understood. Electroencephalography (EEG)...
Dyslexia is one of the most studied learning disorders. Despite this, its biological basis and main causes are still not fully understood. Electroencephalography (EEG) could be a powerful tool in identifying the underlying mechanisms, but knowledge of the EEG correlates of developmental dyslexia (DD) remains elusive. We aimed to systematically review the evidence on EEG correlates of DD and establish their quality. In July 2021, we carried out an online search of the PubMed and Scopus databases to identify published articles on EEG correlates in children with dyslexia aged 6 to 12 years without comorbidities. We follow the PRISMA guidelines and assess the quality using the Appraisal Tool questionnaire. Our final analysis included 49 studies (14% high quality, 63% medium, 20% low, and 2% very low). Studies differed greatly in methodology, making a summary of their results challenging. However, some points came to light. Even at rest, children with dyslexia and children in the control group exhibited differences in several EEG measures, particularly in theta and alpha frequencies; these frequencies appear to be associated with learning performance. During reading-related tasks, the differences between dyslexic and control children seem more localized in the left temporoparietal sites. The EEG activity of children with dyslexia and children in the control group differed in many aspects, both at rest and during reading-related tasks. Our data are compatible with neuroimaging studies in the same diagnostic group and expand the literature by offering new insights into functional significance.
Topics: Child; Humans; Dyslexia; Reading; Electroencephalography; Learning Disabilities
PubMed: 36417146
DOI: 10.1007/s11881-022-00273-1 -
No To Hattatsu = Brain and Development May 2015
Topics: Attention Deficit and Disruptive Behavior Disorders; Autistic Disorder; Dyslexia; Humans; Incidence
PubMed: 26211336
DOI: No ID Found -
Scientific Reports Mar 2021Individuals with dyslexia present with reading-related deficits including inaccurate and/or less fluent word recognition and poor decoding abilities. Slow reading speed...
Individuals with dyslexia present with reading-related deficits including inaccurate and/or less fluent word recognition and poor decoding abilities. Slow reading speed and worse text comprehension can occur as secondary consequences of these deficits. Reports of visual symptoms such as atypical eye movements during reading gave rise to a search for these deficits' underlying mechanisms. This study sought to replicate established behavioral deficits in reading and cognitive processing speed while investigating their underlying mechanisms in more detail by developing a comprehensive profile of eye movements specific to reading in adult dyslexia. Using a validated standardized reading assessment, our findings confirm a reading speed deficit among adults with dyslexia. We observed different eye movements in readers with dyslexia across numerous eye movement metrics including the duration of a stop (i.e., fixation), the length of jumps (i.e., saccades), and the number of times a reader's eyes expressed a jump atypical for reading. We conclude that individuals with dyslexia visually sample written information in a laborious and more effortful manner that is fundamentally different from those without dyslexia. Our findings suggest a mix of aberrant cognitive linguistic and oculomotor processes being present in adults with dyslexia.
Topics: Adolescent; Adult; Dyslexia; Eye Movements; Female; Humans; Male; Reading; Visual Perception
PubMed: 33742007
DOI: 10.1038/s41598-021-84945-9