Grapheme-phoneme learning in an unknown orthography: a study in typical reading and dyslexic children

In this study, we examined the learning of new grapheme-phoneme correspondences in individuals with and without dyslexia. Additionally, we investigated the relation between grapheme-phoneme learning and measures of phonological awareness, orthographic knowledge and rapid automatized naming, with a focus on the unique joint variance of grapheme-phoneme learning to word and non-word reading achievement. Training of grapheme-phoneme associations consisted of a 20-min training program in which eight novel letters (Hebrew) needed to be paired with speech sounds taken from the participant's native language (Dutch). Eighty-four third grade students, of whom 20 were diagnosed with dyslexia, participated in the training and testing. Our results indicate a reduced ability of dyslexic readers in applying newly learned grapheme-phoneme correspondences while reading words which consist of these novel letters. However, we did not observe a significant independent contribution of grapheme-phoneme learning to reading outcomes. Alternatively, results from the regression analysis indicate that failure to read may be due to differences in phonological and/or orthographic knowledge but not to differences in the grapheme-phoneme-conversion process itself

Grapheme-Phoneme Learning in an Unknown Orthography: A Study in Typical Reading and Dyslexic Children

In this study, we examined the learning of new grapheme-phoneme correspondences in individuals with and without dyslexia. Additionally, we investigated the relation between grapheme-phoneme learning and measures of phonological awareness, orthographic knowledge and rapid automatized naming, with a focus on the unique joint variance of grapheme-phoneme learning to word and non-word reading achievement. Training of grapheme-phoneme associations consisted of a 20-min training program in which eight novel letters (Hebrew) needed to be paired with speech sounds taken from the participant's native language (Dutch). Eighty-four third grade students, of whom 20 were diagnosed with dyslexia, participated in the training and testing. Our results indicate a reduced ability of dyslexic readers in applying newly learned grapheme-phoneme correspondences while reading words which consist of these novel letters. However, we did not observe a significant independent contribution of grapheme-phoneme learning to reading outcomes. Alternatively, results from the regression analysis indicate that failure to read may be due to differences in phonological and/or orthographic knowledge but not to differences in the grapheme-phoneme-conversion process itself

SPEKTRALANALYTISCHE AUSWERTUNG SPANNUNGSOPTISCHER BILDER

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.ISSN:1053-8119ISSN:1095-957

The development of the neuroanatomical reading network in children at risk for developmental dyslexia

Although our brain is not predestined for reading, as alphabetic scripts exist for around 3000 years, the vast majority of the population learns to read fluently, presumably by reorganizing the already established visual and language brain network. However, 3 to 7% of the children do not learn to read fluently, and they develop dyslexia. According to the multiple deficit model of Pennington (2006) the aetiology of developmental dyslexia is multifactorial. Hence, developmental dyslexia is thought to result from impairments at different levels, i.e. the genetic, neurobiological, environmental and cognitive level, and from the interactions between these levels. Previous neuroimaging studies gained insights into the neural correlates of mature reading, showing that reading generally involves a widespread network of distinct regions in the left hemisphere of the brain. To date, it remains unclear how the brain reorganizes throughout the first stages of reading acquisition, and whether deviances in children with (a familial risk for) dyslexia are present prior to reading onset or emerge during reading acquisition. By three longitudinal studies (Chapters 2, 3, 5) and one methodological oriented study (Chapter 4), the main anatomical region considered to host phonemic representations, i.e. the planum temporale, and the most relevant white matter pathways are studied in relation to reading and to different levels of the multiple deficit model. In the first study (Chapter 2), we investigated planum temporale surface area in pre-readers and in adolescents. The results revealed atypical lateralization of the planum temporale in relation to a family history of dyslexia, rather than to the (later) reading level. In the second study (Chapter 3), we applied diffusion tensor imaging (DTI) to investigate previously reported white matter anomalies in adults with dyslexia, in a longitudinal sample of pre-readers and early readers. We demonstrated that white matter deviances in the dorsal arcuate fasciculus are dynamic and precede reading acquisition, and moreover, ventral white matter deviances were detected in relation to a family history of dyslexia. The latter deviances were stable over time. Finally, we aimed at investigating reading induced structural brain changes, especially with regard to phonological processing and orthographic knowledge. Therefore, the higher order non-tensor Spherical Deconvolution (SD) model was applied. The results revealed that the relation between dorsal white matter and phonological processing precedes reading acquisition, and this relation is specific to the arcuate fasciculus (Chapter 4). The specialization of ventral white matter for orthographic knowledge, especially in the left inferior fronto-occipital fasciculus, emerges throughout the early stages of reading acquisition (Chapter 5). The results obtained within this doctoral dissertation are further discussed in a general discussion (Chapter 6). In sum, we demonstrate that neuroanatomical deviances can precede reading acquisition and that neural reorganization parallels the initial stages of reading development. While some deviances seem to relate to the emergence of developmental dyslexia, other deviances are merely related to a familial risk for dyslexia. These results emphasize the complex aetiology of developmental dyslexia.status: publishe

La détection précoce des troubles du langage: enjeux et perspectives.

Une équipe d'auteurs internationale et pluridisciplinaire livre l'état de la recherche et de la clinique sur la rééducation du langage. Ce livre édité sous l’égide de la Société de Neuropsychologie de Langue Française présente les données les plus récentes dans le domaine du diagnostic, de l’évaluation et de la prise en charge des troubles langagiers. Il aborde non seulement les troubles du langage acquis (aphasies, y compris les aphasies d’origine neurodégénérative) mais encore les troubles développementaux du langage. Les auteurs présentent des nouveautés théoriques, cliniques et neurobiologiques encore peu connues par les chercheurs et professionnels du domaine des troubles du langage, ainsi que de nouveaux outils d’évaluation et de rééducation qui seront très utiles aux cliniciens orthophonistes, neuropsychologues, neurologues et neuropédiatres

Research Insights on Neural Effects of Auditory Deprivation and Restoration in Unilateral Hearing Loss: A Systematic Review

Neuroplasticity following bilateral deafness and auditory restoration has been repeatedly investigated. In clinical practice, however, a significant number of patients present a severe-to-profound unilateral hearing loss (UHL). To date, less is known about the neuroplasticity following monaural hearing deprivation and auditory input restoration. This article provides an overview of the current research insights on the impact of UHL on the brain and the effect of auditory input restoration with a cochlear implant (CI). An exhaustive systematic review of the literature was performed selecting 38 studies that apply different neural analyses techniques. The main results show that the hearing ear becomes functionally dominant after monaural deprivation, reshaping the lateralization of the neural network for auditory processing, a process that can be considered to influence auditory restoration. Furthermore, animal models predict that the onset time of UHL impacts auditory restoration. Hence, the results seem to advocate for early restoration of UHL, although further research is required to disambiguate the effects of duration and onset of UHL on auditory restoration and on structural neuroplasticity following UHL deprivation and restoration. Ongoing developments on CI devices compatible with Magnetic Resonance Imaging (MRI) examinations will provide a unique opportunity to investigate structural and functional neuroplasticity following CI restoration more directly.status: publishe

Les compétences de traitement phonologique chez les adultes avec une dyslexie

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Morphological awareness and visual processing of derivational morphology in high functioning adults with dyslexia: An avenue to compensation?

This study examined the processing of derivational morphology and its association with measures of morphological awareness and literacy outcomes in 30 Dutch speaking high functioning dyslexics, and 30 controls, matched for age and reading comprehension. A masked priming experiment was conducted where the semantic overlap between morphologically related pairs was manipulated as part of a lexical decision task. Measures of morphological awareness were assessed using a specifically designed sentence completion task. Significant priming effects were found in each group, yet adults with dyslexia were found to benefit more from the morphological structure than the controls. Adults with dyslexia were found to be influenced by both form (morpho-orthographic) and meaning (morpho-semantic) properties of morphemes while controls were mainly influenced by morpho-semantic properties. Results suggest that morphological processing is intact in high-functioning dyslexics and a strength when compared to controls matched for reading comprehension and age. Thus, supporting morphological processing as a potential factor in the reading compensation of adults with dyslexia. However, adults with dyslexia performed significantly worse than controls on morphological awareness measures.status: publishe

Hersenconnectiviteit in relatie tot lezen en leesproblemen: een diffusie MRI studie bij kleuters en volwassenen

Het standaard neuraal ontwikkelingsmodel van lezen veronderstelt dat de primaire problemen bij dyslexie samenhangen met afwijkingen in de linker dorsale hersenregio’s, die instaan voor fonologische verwerking en decoderend lezen. Secundair en later in de ontwikkeling zouden zich ook problemen voordoen in de linker ventrale hersenregio’s, die instaan voor orthografische verwerking en directe woordherkenning. De huidige studie tracht deze sequentiële assumptie te verifiëren door, aan de hand van diffusie-gewogen beeldvorming (DTI), de dorsale en ventrale hersenbundels te onderzoeken bij volwassenen met dyslexie (n = 40) en bij kleuters die nog niet kunnen lezen (n = 71). Bij volwassenen met dyslexie werden er afwijkingen gevonden in linker dorsale hersenbundels. Bijkomend vonden we een relatie tussen de kwaliteit van deze linker dorsale bundels en fonologie, terwijl de kwaliteit van de linker ventrale bundels met orthografie gelinkt zijn. De afwijkingen die we bij jonge kinderen met een familiaal risico op dyslexie vaststellen, bevinden zich op een andere locatie en hebben een andere functie dan bij de volwassenen met dyslexie. Het vinden van afwijkingen bij kleuters met een familiaal risico op dyslexie zou erop kunnen wijzen dat deze afwijkingen een neurale oorzaak vormen van dyslexie,maar verder longitudinaal onderzoek is nodig om dit te verduidelijken