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Bert De Smedt - One of the best experts on this subject based on the ideXlab platform.
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Cognitive correlates of dyslexia, Dyscalculia and comorbid dyslexia/Dyscalculia: Effects of numerical magnitude processing and phonological processing
Research in developmental disabilities, 2020Co-Authors: Lien Peters, Hans Op De Beeck, Bert De SmedtAbstract:Abstract Specific learning disorders (i.e., Dyscalculia and dyslexia) are common, as is their comorbidity. It has been suggested that the core cognitive deficit in Dyscalculia is an impairment in numerical magnitude processing; similarly, in dyslexia, phonological processing deficits are considered to be the main cognitive deficit. Cognitive theories on comorbid dyslexia/Dyscalculia have suggested a number of hypotheses about which cognitive deficits underlie the comorbidity. However, few studies have thus far directly compared the abovementioned cognitive correlates of Dyscalculia and dyslexia. In this study, we assessed symbolic and non-symbolic numerical magnitude and three subcomponents of phonological processing (phonological awareness, lexical access and verbal short-term memory). In addition, we investigated children’s domain-general spatial and verbal skills. The effect of these cognitive correlates on Dyscalculia, dyslexia and their comorbidity was explored. We did not find differences between children with and without Dyscalculia on numerical magnitude processing. On the other hand, children with Dyscalculia had significantly lower spatial skills compared to children without Dyscalculia. Children with dyslexia performed significantly lower on all subcomponents of phonological processing. Finally, we found an additive effect for comorbid dyslexia/Dyscalculia: impairments in children with co-occurring dyslexia and Dyscalculia were similar to the sum of the impairments in the isolated dyslexia and isolated Dyscalculia groups. The strongest unique predictor of isolated Dyscalculia and comorbid dyslexia/Dyscalculia was spatial skills, the strongest unique predictor of isolated dyslexia was phonological awareness. As only a limited number of cognitive variables were assessed in this study and the sample sizes were very small, we should be cautious when interpreting these results.
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cognitive correlates of dyslexia Dyscalculia and comorbid dyslexia Dyscalculia effects of numerical magnitude processing and phonological processing
Research in Developmental Disabilities, 2020Co-Authors: Lien Peters, Hans Op De Beeck, Bert De SmedtAbstract:Abstract Specific learning disorders (i.e., Dyscalculia and dyslexia) are common, as is their comorbidity. It has been suggested that the core cognitive deficit in Dyscalculia is an impairment in numerical magnitude processing; similarly, in dyslexia, phonological processing deficits are considered to be the main cognitive deficit. Cognitive theories on comorbid dyslexia/Dyscalculia have suggested a number of hypotheses about which cognitive deficits underlie the comorbidity. However, few studies have thus far directly compared the abovementioned cognitive correlates of Dyscalculia and dyslexia. In this study, we assessed symbolic and non-symbolic numerical magnitude and three subcomponents of phonological processing (phonological awareness, lexical access and verbal short-term memory). In addition, we investigated children’s domain-general spatial and verbal skills. The effect of these cognitive correlates on Dyscalculia, dyslexia and their comorbidity was explored. We did not find differences between children with and without Dyscalculia on numerical magnitude processing. On the other hand, children with Dyscalculia had significantly lower spatial skills compared to children without Dyscalculia. Children with dyslexia performed significantly lower on all subcomponents of phonological processing. Finally, we found an additive effect for comorbid dyslexia/Dyscalculia: impairments in children with co-occurring dyslexia and Dyscalculia were similar to the sum of the impairments in the isolated dyslexia and isolated Dyscalculia groups. The strongest unique predictor of isolated Dyscalculia and comorbid dyslexia/Dyscalculia was spatial skills, the strongest unique predictor of isolated dyslexia was phonological awareness. As only a limited number of cognitive variables were assessed in this study and the sample sizes were very small, we should be cautious when interpreting these results.
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Multi-method brain imaging reveals impaired representations of number as well as altered connectivity in adults with Dyscalculia
NeuroImage, 2018Co-Authors: Jessica Bulthé, Hans Op De Beeck, Jellina Prinsen, Jolijn Vanderauwera, Stefanie Duyck, Nicky Daniels, Céline R. Gillebert, Dante Mantini, Bert De SmedtAbstract:Two hypotheses have been proposed about the etiology of neurodevelopmental learning disorders, such as dyslexia and Dyscalculia: representation impairments and disrupted access to representations. We implemented a multi-method brain imaging approach to directly investigate these representation and access hypotheses in Dyscalculia, a highly prevalent but understudied neurodevelopmental disorder in learning to calculate. We combined several magnetic resonance imaging methods and analyses, including univariate and multivariate analyses, functional and structural connectivity. Our sample comprised 24 adults with Dyscalculia and 24 carefully matched controls. Results showed a clear deficit in the non-symbolic magnitude representations in parietal, temporal and frontal regions, as well as hyper-connectivity in visual brain regions in adults with Dyscalculia. Dyscalculia in adults was thereby related to both impaired number representations and altered connectivity in the brain. We conclude that Dyscalculia is related to impaired number representations as well as altered access to these representations.
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Dyscalculia and dyslexia: Different behavioral, yet similar brain activity profiles during arithmetic
NeuroImage. Clinical, 2018Co-Authors: Lien Peters, Hans Op De Beeck, Jessica Bulthé, Nicky Daniels, Bert De SmedtAbstract:Brain disorders are often investigated in isolation, but very different conclusions might be reached when studies directly contrast multiple disorders. Here, we illustrate this in the context of specific learning disorders, such as Dyscalculia and dyslexia. While children with Dyscalculia show deficits in arithmetic, children with dyslexia present with reading difficulties. Furthermore, the comorbidity between dyslexia and Dyscalculia is surprisingly high. Different hypotheses have been proposed on the origin of these disorders (number processing deficits in Dyscalculia, phonological deficits in dyslexia) but these have never been directly contrasted in one brain imaging study. Therefore, we compared the brain activity of children with dyslexia, children with Dyscalculia, children with comorbid dyslexia/Dyscalculia and healthy controls during arithmetic in a design that allowed us to disentangle various processes that might be associated with the specific or common neural origins of these learning disorders. Participants were 62 children aged 9 to 12, 39 of whom had been clinically diagnosed with a specific learning disorder (Dyscalculia and/or dyslexia). All children underwent fMRI scanning while performing an arithmetic task in different formats (dot arrays, digits and number words). At the behavioral level, children with Dyscalculia showed lower accuracy when subtracting dot arrays, and all children with learning disorders were slower in responding compared to typically developing children (especially in symbolic formats). However, at the neural level, analyses pointed towards substantial neural similarity between children with learning disorders: Control children demonstrated higher activation levels in frontal and parietal areas than the three groups of children with learning disorders, regardless of the disorder. A direct comparison between the groups of children with learning disorders revealed similar levels of neural activation throughout the brain across these groups. Multivariate subject generalization analyses were used to statistically test the degree of similarity, and confirmed that the neural activation patterns of children with dyslexia, Dyscalculia and dyslexia/Dyscalculia were highly similar in how they deviated from neural activation patterns in control children. Collectively, these results suggest that, despite differences at the behavioral level, the brain activity profiles of children with different learning disorders during arithmetic may be more similar than initially thought.
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Multi-method brain imaging reveals impaired representations as well as altered connectivity in adults with Dyscalculia
2017Co-Authors: Jessica Bulthé, Hans Op De Beeck, Jellina Prinsen, Jolijn Vanderauwera, Stefanie Duyck, Nicky Daniels, Céline R. Gillebert, Dante Mantini, Bert De SmedtAbstract:Two hypotheses have been proposed about the etiology of neurodevelopmental disorders: representation impairments versus disrupted access to representations. We implemented a multi-method brain imaging approach to directly compare the representation vs. access hypotheses in Dyscalculia, a highly prevalent but understudied neurodevelopmental disorder in learning to calculate. We combined several magnetic resonance imaging methods and analyses, including multivariate analyses, functional and structural connectivity, and voxel-based morphometry analysis, in a sample of 24 adults with Dyscalculia and 24 carefully matched controls. Results showed a clear deficit in the non-symbolic magnitude representations in parietal, temporal, and frontal regions in Dyscalculia. We also observed hyper-connectivity in visual brain regions and increased grey matter volume in the default mode network in adults with Dyscalculia. Hence, Dyscalculia is related to a combination of diverse neural markers which are altogether distributed across a substantial portion of cerebral cortex, supporting a multifactorial model of this neurodevelopmental disorder.
Lien Peters - One of the best experts on this subject based on the ideXlab platform.
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Cognitive correlates of dyslexia, Dyscalculia and comorbid dyslexia/Dyscalculia: Effects of numerical magnitude processing and phonological processing
Research in developmental disabilities, 2020Co-Authors: Lien Peters, Hans Op De Beeck, Bert De SmedtAbstract:Abstract Specific learning disorders (i.e., Dyscalculia and dyslexia) are common, as is their comorbidity. It has been suggested that the core cognitive deficit in Dyscalculia is an impairment in numerical magnitude processing; similarly, in dyslexia, phonological processing deficits are considered to be the main cognitive deficit. Cognitive theories on comorbid dyslexia/Dyscalculia have suggested a number of hypotheses about which cognitive deficits underlie the comorbidity. However, few studies have thus far directly compared the abovementioned cognitive correlates of Dyscalculia and dyslexia. In this study, we assessed symbolic and non-symbolic numerical magnitude and three subcomponents of phonological processing (phonological awareness, lexical access and verbal short-term memory). In addition, we investigated children’s domain-general spatial and verbal skills. The effect of these cognitive correlates on Dyscalculia, dyslexia and their comorbidity was explored. We did not find differences between children with and without Dyscalculia on numerical magnitude processing. On the other hand, children with Dyscalculia had significantly lower spatial skills compared to children without Dyscalculia. Children with dyslexia performed significantly lower on all subcomponents of phonological processing. Finally, we found an additive effect for comorbid dyslexia/Dyscalculia: impairments in children with co-occurring dyslexia and Dyscalculia were similar to the sum of the impairments in the isolated dyslexia and isolated Dyscalculia groups. The strongest unique predictor of isolated Dyscalculia and comorbid dyslexia/Dyscalculia was spatial skills, the strongest unique predictor of isolated dyslexia was phonological awareness. As only a limited number of cognitive variables were assessed in this study and the sample sizes were very small, we should be cautious when interpreting these results.
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cognitive correlates of dyslexia Dyscalculia and comorbid dyslexia Dyscalculia effects of numerical magnitude processing and phonological processing
Research in Developmental Disabilities, 2020Co-Authors: Lien Peters, Hans Op De Beeck, Bert De SmedtAbstract:Abstract Specific learning disorders (i.e., Dyscalculia and dyslexia) are common, as is their comorbidity. It has been suggested that the core cognitive deficit in Dyscalculia is an impairment in numerical magnitude processing; similarly, in dyslexia, phonological processing deficits are considered to be the main cognitive deficit. Cognitive theories on comorbid dyslexia/Dyscalculia have suggested a number of hypotheses about which cognitive deficits underlie the comorbidity. However, few studies have thus far directly compared the abovementioned cognitive correlates of Dyscalculia and dyslexia. In this study, we assessed symbolic and non-symbolic numerical magnitude and three subcomponents of phonological processing (phonological awareness, lexical access and verbal short-term memory). In addition, we investigated children’s domain-general spatial and verbal skills. The effect of these cognitive correlates on Dyscalculia, dyslexia and their comorbidity was explored. We did not find differences between children with and without Dyscalculia on numerical magnitude processing. On the other hand, children with Dyscalculia had significantly lower spatial skills compared to children without Dyscalculia. Children with dyslexia performed significantly lower on all subcomponents of phonological processing. Finally, we found an additive effect for comorbid dyslexia/Dyscalculia: impairments in children with co-occurring dyslexia and Dyscalculia were similar to the sum of the impairments in the isolated dyslexia and isolated Dyscalculia groups. The strongest unique predictor of isolated Dyscalculia and comorbid dyslexia/Dyscalculia was spatial skills, the strongest unique predictor of isolated dyslexia was phonological awareness. As only a limited number of cognitive variables were assessed in this study and the sample sizes were very small, we should be cautious when interpreting these results.
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Dyscalculia and dyslexia: Different behavioral, yet similar brain activity profiles during arithmetic
NeuroImage. Clinical, 2018Co-Authors: Lien Peters, Hans Op De Beeck, Jessica Bulthé, Nicky Daniels, Bert De SmedtAbstract:Brain disorders are often investigated in isolation, but very different conclusions might be reached when studies directly contrast multiple disorders. Here, we illustrate this in the context of specific learning disorders, such as Dyscalculia and dyslexia. While children with Dyscalculia show deficits in arithmetic, children with dyslexia present with reading difficulties. Furthermore, the comorbidity between dyslexia and Dyscalculia is surprisingly high. Different hypotheses have been proposed on the origin of these disorders (number processing deficits in Dyscalculia, phonological deficits in dyslexia) but these have never been directly contrasted in one brain imaging study. Therefore, we compared the brain activity of children with dyslexia, children with Dyscalculia, children with comorbid dyslexia/Dyscalculia and healthy controls during arithmetic in a design that allowed us to disentangle various processes that might be associated with the specific or common neural origins of these learning disorders. Participants were 62 children aged 9 to 12, 39 of whom had been clinically diagnosed with a specific learning disorder (Dyscalculia and/or dyslexia). All children underwent fMRI scanning while performing an arithmetic task in different formats (dot arrays, digits and number words). At the behavioral level, children with Dyscalculia showed lower accuracy when subtracting dot arrays, and all children with learning disorders were slower in responding compared to typically developing children (especially in symbolic formats). However, at the neural level, analyses pointed towards substantial neural similarity between children with learning disorders: Control children demonstrated higher activation levels in frontal and parietal areas than the three groups of children with learning disorders, regardless of the disorder. A direct comparison between the groups of children with learning disorders revealed similar levels of neural activation throughout the brain across these groups. Multivariate subject generalization analyses were used to statistically test the degree of similarity, and confirmed that the neural activation patterns of children with dyslexia, Dyscalculia and dyslexia/Dyscalculia were highly similar in how they deviated from neural activation patterns in control children. Collectively, these results suggest that, despite differences at the behavioral level, the brain activity profiles of children with different learning disorders during arithmetic may be more similar than initially thought.
Enguo Wang - One of the best experts on this subject based on the ideXlab platform.
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Old/New Effect of Digital Memory Retrieval in Chinese Dyscalculia: Evidence from ERP
Journal of learning disabilities, 2016Co-Authors: Enguo WangAbstract:This study reports the neurophysiological and behavioral correlates of digital memory retrieval features in Chinese individuals with and without Dyscalculia. A total of 18 children with Dyscalculia (ages 11.5-13.5) and 18 controls were tested, and their event-related potentials were digitally recorded simultaneously with behavior measurement. Behavioral data showed that the Dyscalculia group had lower hit rates and higher false rates than the control group. The electroencephalography results showed that both groups had a significant old/new effect and that this effect was greater in the control group. In the 300 to 400 ms processing stages, both groups showed significant differences in digital memory retrieval in the frontal regions. In the 400 to 500 and 500 to 600 ms epochs, the old/new effect in the control group was significantly greater than it was in the Dyscalculia group at the frontal, central, and parietal regions. In the 600 to 700 ms processing stages, both groups showed significant differences in digital memory retrieval in the frontal, central, parietal, and occipital regions. These results suggest that individuals with Dyscalculia exhibit impaired digital memory retrieval. Extraction failure may be an important cause of calculation difficulties.
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Digital Memory Encoding Characteristics in Chinese Dyscalculia
Brain disorders & therapy, 2015Co-Authors: Enguo WangAbstract:We know remarkably little about deficits in memory impairment calculation. This study reports the neurophysiological and behavioral correlates of digital memory encoding features in Chinese individuals with and without Dyscalculia. The results showed that individuals with Dyscalculia exhibit impaired digital memory encoding and deficits in psychological resource allocation.
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Digital memory encoding in Chinese Dyscalculia: An event-related potential study.
Research in Developmental Disabilities, 2015Co-Authors: Enguo Wang, Shutao Qin, Mengyan Chang, Xiangru ZhuAbstract:This study reports the neurophysiological and behavioral correlates of digital memory encoding features in Chinese individuals with and without Dyscalculia. Eighteen children with Dyscalculia (ages 11.5-13.5) and 18 matched controls were tested, and their event-related potentials (ERPs) were digitally recorded simultaneously with behavioral measures. The results showed that both groups had a significant Dm effect, and this effect was greater in the control group. In the 300-400-ms, 400-500-ms, and 600-700-ms processing stages, both groups showed significant differences of digital memory encoding in the frontal, central, and parietal regions. In the 500-600-ms period, the Dm effect in the control group was significantly greater than that in the Dyscalculia group only in the parietal region. These results suggest that individuals with Dyscalculia exhibit impaired digital memory encoding and deficits in psychological resource allocation.
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Developmental Dyscalculia of Digital Memory Retrieval
Journal of Neurology and Neuroscience, 2015Co-Authors: Enguo WangAbstract:We know remarkably little about deficits in memory impairment calculation. This study reports the neurophysiological and behavioral correlates of digital memory retrieval features in Chinese individuals with and without Dyscalculia. Children with Dyscalculia and control groups were tested and their event-related potentials (ERPs) were digitally recorded simultaneously with behavior measurement. Behavioral data showed that the Dyscalculia group had lower hit rates and higher false rates than the control group. The EEG results showed that both groups showed significant differences in digital memory retrieval in the frontal, central, parietal and occipital regions. These results suggest that individuals with Dyscalculia exhibit impaired digital memory retrieval. Extraction failure may be an important cause of calculation difficulties.
Karin Kucian - One of the best experts on this subject based on the ideXlab platform.
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The Importance of Central-Visual Perception Disorders for Dyslexia and Dyscalculia
Neuropediatrics, 2017Co-Authors: Karin KucianAbstract:Visual perception disorders can lead to different learning disorders in children. These are often difficulties in reading and writing, as well as in calculation and number processing.\ud Dyslexia, the specific reading and spelling disorder, is also associated with various deficits of visual perception which, for example, make it difficult to distinguish between individual letters or impair the text-dependent eye movements. From a neural point of view, the visual word form area (VWFA) in the fusiform gyrus, which is responsible for the visual processing of orthographic information must be highlighted, since the VWFA is often disturbed in dyslexics.\ud Dyscalculia, the specific calculation disorder, is often associated with difficulties in visual-spatial processing. This is not surprising since our mental representation of numbers and magnitudes is spatially organized. This means we have a kind of mental number line on which we store numbers according to their magnitude. In the case of Dyscalculia, the construction and the automated access to this mental number line are often disturbed. This mental number line is located in the intraparietal sulcus (IPS) of the brain, the region which shows increased abnormalities in Dyscalculia, such as volume differences of gray matter, reduced activation or reduced connection to other cortical areas.\ud Although central-visual perception disorders can clearly lead to learning disabilities of reading and writing, as well as calculation, dyslexia or Dyscalculia is defined only when organic causes can be ruled out, which is why a differentiation between classical dyslexia or Dyscalculia and problems in reading/writing and calculation due to visual deficits is necessary
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adolescents with developmental Dyscalculia do not have a generalized magnitude deficit processing of discrete and continuous magnitudes
Frontiers in Human Neuroscience, 2017Co-Authors: Ursina Mccaskey, Karin Kucian, Michael Von Aster, Ruth Ogorman TuuraAbstract:The link between number and space has been discussed in the literature for some time, resulting in the theory that number, space and time might be part of a generalized magnitude system. To date, several behavioral and neuroimaging findings support the notion of a generalized magnitude system, although contradictory results showing a partial overlap or separate magnitude systems are also found. The possible existence of a generalized magnitude processing area leads to the question how individuals with developmental Dyscalculia (DD), known for deficits in numerical-arithmetical abilities, process magnitudes. By means of neuropsychological tests and functional magnetic resonance imaging (fMRI) we aimed to examine the relationship between number and space in typical and atypical development. Participants were 16 adolescents with DD (14.1 years) and 14 typically developing (TD) peers (13.8 years). In the fMRI paradigm participants had to perform discrete (arrays of dots) and continuous magnitude (angles) comparisons as well as a mental rotation task. In the neuropsychological tests, adolescents with Dyscalculia performed significantly worse in numerical and complex visuo-spatial tasks. However, they showed similar results to TD peers when making discrete and continuous magnitude decisions during the neuropsychological tests and the fMRI paradigm. A conjunction analysis of the fMRI data revealed commonly activated higher order visual (inferior and middle occipital gyrus) and parietal (inferior and superior parietal lobe) magnitude areas for the discrete and continuous magnitude tasks. Moreover, no differences were found when contrasting both magnitude processing conditions, favoring the possibility of a generalized magnitude system. Group comparisons further revealed that dyscalculic subjects showed increased activation in domain general regions, whilst TD peers activate domain specific areas to a greater extent. In conclusion, our results point to the existence of a generalized magnitude system in the occipito-parietal stream in typical development. The detailed investigation of spatial and numerical magnitude abilities in DD reveals that the deficits in number processing and arithmetic cannot be explained with a general magnitude deficiency. Our results further indicate that multiple neuro-cognitive components might contribute to the explanation of DD.
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Developmental Dyscalculia: a dysconnection syndrome?
Brain Structure and Function, 2014Co-Authors: Karin Kucian, Lutz Jäncke, Simone Schwizer Ashkenazi, Jürgen Hänggi, Stephanie Rotzer, Ernst Martin, Michael AsterAbstract:Numerical understanding is important for everyday life. For children with developmental Dyscalculia (DD), numbers and magnitudes present profound problems which are thought to be based upon neuronal impairments of key regions for numerical understanding. The aim of the present study was to investigate possible differences in white matter fibre integrity between children with DD and controls using diffusion tensor imaging. White matter integrity and behavioural measures were evaluated in 15 children with developmental Dyscalculia aged around 10 years and 15 matched controls. The main finding, obtained by a whole brain group comparison, revealed reduced fractional anisotropy in the superior longitudinal fasciculus in children with developmental Dyscalculia. In addition, a region of interest analysis exhibited prominent deficits in fibres of the superior longitudinal fasciculus adjacent to the intraparietal sulcus, which is thought to be the core region for number processing. To conclude, our results outline deficient fibre projection between parietal, temporal and frontal regions in children with developmental Dyscalculia, and therefore raise the question of whether Dyscalculia can be seen as a dysconnection syndrome. Since the superior longitudinal fasciculus is involved in the integration and control of distributed brain processes, the present results highlight the importance of considering broader domain-general mechanisms in the diagnosis and therapy of Dyscalculia.
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non symbolic numerical distance effect in children with and without developmental Dyscalculia a parametric fmri study
Developmental Neuropsychology, 2011Co-Authors: Karin Kucian, Ernst Martin, Thomas Loenneker, Michael Von AsterAbstract:This study investigated areas of brain activation related to non-symbolic distance effects in children with and without developmental Dyscalculia (DD). We examined 15 children with DD (11.3 years) and 15 controls (10.6 years) by means of functional magnetic resonance imaging (fMRI). Both groups displayed similar behavioral performance, but differences in brain activation were observed, particularly in the supplementary motor area and the right fusiform gyrus, where children with DD demonstrated stronger activation. These results suggest that dyscalculic children engage areas attributed to higher difficulty in response selection more than control children, possibly due to a deficient development of a spatial number representation in DD.
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optimized voxel based morphometry in children with developmental Dyscalculia
NeuroImage, 2008Co-Authors: Stephanie Rotzer, Karin Kucian, Ernst Martin, Thomas Loenneker, M Von Aster, Peter KlaverAbstract:Developmental Dyscalculia (DD) is a specific learning disability affecting the normal acquisition of arithmetic skills. Current studies estimate that 3-6% of the school population is affected by DD. Genetic, neurobiological, and epidemiologic evidence indicates that Dyscalculia is a brain-based disorder. Imaging studies suggest the involvement of parietal and prefrontal cortices in arithmetic tasks. The aim of the present study was to analyze if children with DD show structural differences in parietal, frontal, and cingulate areas compared to typically achieving children. Magnetic resonance imaging was obtained from 12 children with DD aged 9.3+/-0.2 years and 12 age-matched control children without any learning disabilities on a 1.5 T whole-body scanner. Voxel-based morphometry analysis with an optimization of spatial segmentation and normalization procedures was applied to compare the two groups in order to find differences in cerebral gray and white matter. Compared to controls, children with DD show significantly reduced gray matter volume in the right intraparietal sulcus (IPS), the anterior cingulum, the left inferior frontal gyrus, and the bilateral middle frontal gyri. White matter comparison demonstrates clusters with significantly less volume in the left frontal lobe and in the right parahippocampal gyrus in dyscalculic children. The decreased gray and white matter volumes in the frontoparietal network might be the neurological substrate of impaired arithmetic processing skills. The white matter volume decrease in parahippocampal areas may have influence on fact retrieval and spatial memory processing.
Karin Landerl - One of the best experts on this subject based on the ideXlab platform.
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core deficit and individual manifestations of developmental Dyscalculia dd the role of comorbidity
Trends in Neuroscience and Education, 2013Co-Authors: Karin Landerl, Kristina Moll, Silke M GobelAbstract:Abstract Among individuals with Dyscalculia, prevalence rates for other developmental problems are clearly higher than in the general population. Comorbidity itself therefore constitutes a central characteristic of Dyscalculia. Thus, research designs are needed which explicitly account for comorbid problems in order to examine the specificity of any risk or protective factor. Multiple-deficit models seem best suited to explain the heterogeneity of Dyscalculia. Numerical processing is proposed as a core deficit associated with problems in arithmetic skills. Individual manifestations of Dyscalculia, however, arise from a complex interplay of deficits in numerical processing with other neurobiological, cognitive and environmental factors. The exact nature of these interactions has yet to be determined. Implications of multiple-deficit models for research and clinical practice are discussed.
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Dyslexia and Dyscalculia: Two Learning Disorders with Different Cognitive Profiles.
Journal of experimental child psychology, 2009Co-Authors: Karin Landerl, Barbara Fussenegger, Kristina Moll, Edith WillburgerAbstract:This study tests the hypothesis that dyslexia and Dyscalculia are associated with two largely independent cognitive deficits, namely a phonological deficit in the case of dyslexia and a deficit in the number module in the case of Dyscalculia. In four groups of 8- to 10-year-olds (42 control, 21 dyslexic, 20 dyscalculic, and 26 dyslexic/dyscalculic), phonological awareness, phonological and visual-spatial short-term and working memory, naming speed, and basic number processing skills were assessed. A phonological deficit was found for both dyslexic groups, irrespective of additional arithmetic deficits, but not for the Dyscalculia-only group. In contrast, deficits in processing of symbolic and nonsymbolic magnitudes were observed in both groups of dyscalculic children, irrespective of additional reading difficulties, but not in the dyslexia-only group. Cognitive deficits in the comorbid dyslexia/Dyscalculia group were additive; that is, they resulted from the combination of two learning disorders. These findings suggest that dyslexia and Dyscalculia have separable cognitive profiles, namely a phonological deficit in the case of dyslexia and a deficient number module in the case of Dyscalculia.
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basic number processing deficits in developmental Dyscalculia evidence from eye tracking
Cognitive Development, 2009Co-Authors: Korbinian Moeller, Karin Landerl, Liane Kaufmann, S Neuburger, Hc NuerkAbstract:Abstract Recent research suggests that developmental Dyscalculia is associated with a subitizing deficit (i.e., the inability to quickly enumerate small sets of up to 3 objects). However, the nature of this deficit has not previously been investigated. In the present study the eye-tracking methodology was employed to clarify whether (a) the subitizing deficit of two boys with Dyscalculia resulted from a general slowing in the access to magnitude representation, or (b) children with Dyscalculia resort to a back-up counting strategy even for small object sets. In a dot-counting task, a standard problem size effect for the number of fixations required to encode the presented numerosity within the subitizing range was observed. Together with the finding that problem size had no impact on the average fixation duration, this result suggested that children with Dyscalculia may indeed have to count, while typically developing controls are able to enumerate the number of dots in parallel, i.e., subitize. Implications for the understanding of developmental Dyscalculia are considered.
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Naming speed in dyslexia and Dyscalculia
Learning and Individual Differences, 2008Co-Authors: Edith Willburger, Kristina Moll, Barbara Fussenegger, Guilherme Wood, Karin LanderlAbstract:In four carefully selected samples of 8- to 10-year old children with dyslexia (but age adequate arithmetic skills), Dyscalculia (but age adequate reading skills), dyslexia/Dyscalculia and controls a domain-general deficit in rapid automatized naming (RAN) was found for both dyslexia groups. Dyscalculic children exhibited a domain-specific deficit in rapid naming of quantities. This finding is in line with recent assumptions that Dyscalculia is associated with a neurobiological deficit in the processing of numerosities. In the dyslexia/Dyscalculia group, RAN deficits were additive, that is, the dyslexia/Dyscalculia group exhibited the sum of the deficits found in the dyslexia only and Dyscalculia only groups. This finding suggests that the cognitive bases of dyslexia and Dyscalculia are independent from each other. Within the naming speed paradigm no differential impact of special demands on the executive functions inhibition and shifting was found for any of the four groups.
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developmental Dyscalculia and basic numerical capacities a study of 8 9 year old students
Cognition, 2004Co-Authors: Karin Landerl, Anna Bevan, Brian ButterworthAbstract:Thirty-one 8- and 9-year-old children selected for Dyscalculia, reading difficulties or both, were compared to controls on a range of basic number processing tasks. Children with Dyscalculia only had impaired performance on the tasks despite high-average performance on tests of IQ, vocabulary and working memory tasks. Children with reading disability were mildly impaired only on tasks that involved articulation, while children with both disorders showed a pattern of numerical disability similar to that of the dyscalculic group, with no special features consequent on their reading or language deficits. We conclude that Dyscalculia is the result of specific disabilities in basic numerical processing, rather than the consequence of deficits in other cognitive abilities.