Are specific learning disorders truly specific, and are they disorders?

© 2019 The Authors Specific learning disorders, such as dyslexia and dyscalculia, are frequently studied to inform our understanding of cognitive development, genetic mechanisms and brain function. In this Opinion Paper, we discuss limitations of this research approach, including the use of arbitrary criteria to select groups of children, heterogeneity within groups and overlap between domains of learning. By drawing on evidence from cognitive science, neuroscience and genetics, we propose an alternative, dimensional framework. We argue that we need to overcome the problems associated with a categorical approach by taking into account interacting factors at multiple levels of analysis that are associated with overlapping rather than entirely distinct domains of learning. We conclude that this research strategy will allow for a richer understanding of learning and development

Neuroanatomical Correlates of Developmental Dyscalculia: Combined Evidence from Morphometry and Tractography

Poor mathematical abilities adversely affect academic and career opportunities. The neuroanatomical basis of developmental dyscalculia (DD), a specific learning deficit with prevalence rates exceeding 5%, is poorly understood. We used structural MRI and diffusion tensor imaging (DTI) to examine macro- and micro-structural impairments in 7- to 9-year-old children with DD, compared to a group of typically developing (TD) children matched on age, gender, intelligence, reading abilities and working memory capacity. Voxel-based morphometry (VBM) revealed reduced grey matter (GM) bilaterally in superior parietal lobule, intra-parietal sulcus, fusiform gyrus, parahippocampal gyrus and right anterior temporal cortex in children with DD. VBM analysis also showed reduced white matter (WM) volume in right temporal-parietal cortex. DTI revealed reduced fractional anisotropy (FA) in this WM region, pointing to significant right hemisphere micro-structural impairments. Furthermore, FA in this region was correlated with numerical operations but not verbal mathematical reasoning or word reading. Atlas-based tract mapping identified the inferior longitudinal fasciculus, inferior fronto-occipital fasciculus and caudal forceps major as key pathways impaired in DD. DTI tractography suggests that long-range WM projection fibers linking the right fusiform gyrus with temporal-parietal WM are a specific source of vulnerability in DD. Network and classification analysis suggest that DD in children may be characterized by multiple dysfunctional circuits arising from a core WM deficit. Our findings link GM and WM abnormalities in children with DD and they point to macro- and micro-structural abnormalities in right hemisphere temporal-parietal WM, and pathways associated with it, as key neuroanatomical correlates of DD

Early cortical surface plasticity relates to basic mathematical learning

Children lay the foundation for later academic achievement by acquiring core mathematical abilities in the first school years. Neural reorganization processes associated with individual differences in early mathematical learning, however, are still poorly understood. To fill this research gap, we followed a sample of 5-6-year-old children longitudinally to the end of second grade in school (age 7–8 years) combining magnetic resonance imaging (MRI) with comprehensive behavioral assessments. We report significant links between the rate of neuroplastic change of cortical surface anatomy, and children's early mathematical skills. In particular, most of the behavioral variance (about 73%) of children's visuospatial abilities was explained by the change in cortical thickness in the right superior parietal cortex. Moreover, half of the behavioral variance (about 55%) of children's arithmetic abilities was explained by the change in cortical folding in the right intraparietal sulcus. Additional associations for arithmetic abilities were found for cortical thickness change of the right temporal lobe, and the left middle occipital gyrus. Visuospatial abilities were related to right precentral and supramarginal thickness, as well as right medial frontal gyrus folding plasticity. These effects were independent of other individual differences in IQ, literacy and maternal education. Our findings highlight the critical role of cortical plasticity during the acquisition of fundamental mathematical abilities

Correlational Evidence between the Processing Speed Index, Coherent Motion Threshold, and Achievement Scores of Children With and Without Learning Disabilities

The purpose of this study was to determine the responses to three research questions. Is there an inverse relationship between PSI and CMT? Is a score on PSI associated with a child’s performance on math fluency and math calculation? Is CMT associated with PSI on math fluency and math calculation? Academic performance in math was measured by tests of math fluency and calculation. The study investigated the likelihood that a child with a slow PSI will have a high coherent motion threshold (CMT). The diagnostic status groups were comprised of 33 children from 2nd to 8th grades. The children were divided into three groups. One group of children with a learning disability in math only, one group of children with a learning disability in reading and in math, and one group of typically developing children. The group of typically developing subjects served as the control group, and the remaining two groups served as the experimental groups. A correlational research model was used to determine if a relationship exists between Coherent Motion and PSI. A linear regression analysis was conducted to test the correlation between CMT and PSI to gather data relative to the first research question. An Analysis of Variance (ANOVA) was conducted to further test Hypothesis One. Results indicated that there is a moderate negative relationship that exists between PSI and CMT. It was further hypothesized that PSI is associated with a child’s score on math fluency and math calculation, and that CMT is associated with PSI on math fluency and math calculation. A regression analysis was conducted to gather data relative to the second and third research question. Analysis of Variance (ANOVA) was conducted and the findings suggested a moderate negative relationship exist between CMT and PSI. A regression analysis of variance (ANOVA) was used to show the relationship between math fluency and PSI, math calculation and PSI, and math calculation along with math fluency and PSI. The results revealed that a strong direct relationship exists between math fluency, math calculation and processing speed. A regression model was created to determine if PSI and CMT, along with being identified as disabled, can be used as a predictor for math fluency and math calculation scores. When CMT is combined with PSI and students identified as having a disability, the findings revealed that it was not a strong predictor of math fluency and math calculation abilities

The Neuroscience of Mathematical Cognition and Learning

The synergistic potential of cognitive neuroscience and education for efficient learning has attracted considerable interest from the general public, teachers, parents, academics and policymakers alike. This review is aimed at providing 1) an accessible and general overview of the research progress made in cognitive neuroscience research in understanding mathematical learning and cognition, and 2) understanding whether there is sufficient evidence to suggest that neuroscience can inform mathematics education at this point. We also highlight outstanding questions with implications for education that remain to be explored in cognitive neuroscience. The field of cognitive neuroscience is growing rapidly. The findings that we are describing in this review should be evaluated critically to guide research communities, governments and funding bodies to optimise resources and address questions that will provide practical directions for short- and long-term impact on the education of future generations

Test para la identificación de Señales de Dislexia: Evidencia de la Validez de Criterio

In Brazil, there is a lack of valid instruments for screening for Developmental Dyslexia (DD) and so the aim of this study was an in-depth investigation of evidence of validity based on the relations with external variables for the Identifying Signs of Dyslexia Test (TISD). More specifically, it seeks to investigate the validity of the criterion, i.e. whether such instruments would be capable of identifying this diagnosis. The research involved comparing two samples: (a) children with DD diagnosis (n = 15) and (b) children without complaints of reading and writing difficulties (n = 146). It was found that in all the subtests of which the instrument is made up (reading, writing, visual attention, calculation, motor skills, phonological awareness, rapid naming, short term memory) there were significant differences between the groups, and in the test total. The results suggest that the TISD was able to identify the group with DD, evidencing the validity of the criterion for this instrument.No Brasil há escassez de instrumentos validados para triagem da Dislexia do Desenvolvimento (DD), dessa forma, o presente estudo objetivou investigar mais profundamente evidências de validade baseadas nas relações com variáveis externas para o Teste para Identificação de Sinais de Dislexia (TISD). Especificamente, buscou-se investigar a validade de critério, ou seja, se tal instrumento seria capaz de identificar esse diagnóstico. A pesquisa envolveu a comparação de duas amostras: (a) crianças com diagnóstico de DD (n = 15) e (b) crianças sem queixas de dificuldades em leitura e escrita (n = 146). Verificou-se que em todos os subtestes que compõem o instrumento (leitura, escrita, atenção visual, cálculo, habilidades motoras, consciência fonológica, nomeação rápida, memória de curto prazo) houve diferenças significativas entre os grupos, bem como no total do teste. Os resultados sugeriram que o TISD foi capaz de indicar o grupo com DD, o que evidencia validade de critério para tal instrumento.En Brasil hay escasez de instrumentos validados para clasificar la Dislexia del Desarrollo (DD), de esta forma, el presente estudio objetivó investigar más profundamente evidencias de validez basadas en las relaciones con variables externas para la Prueba para Identificación de Señales de Dislexia (PISD). Específicamente, se buscó investigar la validez de criterio, o sea, si tal instrumento fuera capaz de identificar ese diagnóstico. La investigación incluyó la comparación de dos muestras: (a) niños con diagnóstico de DD (n = 15) y (b) niños sin quejas de dificultades en lectura y escritura (n = 146). Se verificó que en todas las subpruebas que componen el instrumento (lectura, escrita, atención visual, cálculo, habilidades motoras, conciencia fonológica, nombramiento rápido, memoria de corto plazo) hubo diferencias significativas entre los grupos, así como en el total de la prueba. Los resultados sugirieron que la PISD fue capaz de indicar el grupo con DD, que evidencia validez de criterio para tal instrumento

Brain Asymmetry in Evolution

In higher mammals, including primates and carnivores, the asymmetrical aspects of brain morphology and function have been shown to be species-related, sex-related, and subject to individual diversity, and are associated with cognition, emotion, language, preference of hand/paw use, and numerous other aspects. Disturbance of the brain lateralization is involved in human neurodevelopmental disorders with cognitive impairments, social deficits, and/or specific language impairments. Asymmetric development may be essential to the evolution of the brain in acquiring higher and/or more diverse functions. The purpose of this Special Issue on “Brain Asymmetry in Evolution” is to highlight morphological and functional lateralization of the brain in various species of mammals toward understanding the evolution of the brain