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Children with specific receptive language impairments (SRLI) have been found to be vulnerable to negative outcomes later in life, in terms of mental health, behaviour and literacy. Currently there is little evidence of the efficacy of speech and language therapy in this area, and a dearth of studies that have investigated interventions for receptive language. Following recommended steps from the Medical Research Council’s guidance for the development of complex interventions, this research focuses on identifying and developing evidence and theory for interventions for SRLI. Evidence of deficit was first explored in a systematic literature review (SLR), examining the nature of the cognitive and linguistic deficits in children with SRLI. Grammar and word learning were identified as areas of particular difficulty for this population. Deficits in information processing, in particular short term and working memory, were also identified as playing a role in these children’s impairments. However, a number of issues were identified with the validity of studies in the area. Theories of therapy were examined in relation to the areas of deficit identified in the SLR through examination of existing intervention studies for children with SRLI, and exploring expert speech and language therapists (SLTs) views in focus groups. Three focus groups with 16 expert SLTs were conducted, followed by a larger group with 23 SLTs who had a range of experience. The groups explored intervention approaches for SRLI, in relation to the deficits identified in the SLR, as well as their rationales for these interventions. It was found that SLTs did not often refer to explicit theories underpinning their intervention for SRLI and had difficulty describing processes of change. However, thematic analysis revealed core therapy components, as well as common approaches for selecting targets across groups. Responses also indicated that the interventions SLTs describe often focus on children’s participation and functioning rather than impairment. The findings of the research are used to present a model of interventions for SRLI. The findings are also drawn upon to examine possible mechanisms of change in interventions for children with SRLI.

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Recent studies have highlighted the co-occurrence of speech disorders with language disorders, yet few studies have attempted to explore the relationship between them. This thesis examines the sentence-level abilities of children with different types of speech disorders, and addresses the following questions: (i) Can children with different types of speech disorders be differentiated according to their sentence-level performance? (ii) Is there a more-than-chance co-occurrence of sentence-level difficulties in children with different types of speech disorders? (iii) What is the relationship between speech disorders and sentence production? (iv) Is sentence imitation an efficient, effective and reliable method of assessing expressive syntax in children with severe speech difficulties? The research focuses on two groups of children, each with a different type of speech disorder: one using atypical phonological processes consistently (CPD) and the other using atypical phonological processes inconsistently (IPD). Their performance was compared to children with SLI and typical development. Results of a group study assessing sentence imitation revealed that children with CPD were no more likely to have co-occurring sentence-level difficulties than typically developing children. The IPD group showed difficulties at the sentence level, with significant variation within the group. Further investigations of sentence processing-related skills found that the IPD group could be divided into those who had IPD only and obtained high sentence imitation scores, and those who had co-occurring IPD and sentence-level difficulties, reflected in their low sentence imitation scores. The performance of the low-scoring IPD children was similar to the SLI group's performance in terms of their sentence imitation accuracy scores and most sentence processing-related abilities. However, they could be differentiated by the types and proportions of their errors and their sentence imitation performance when repeating sentences containing multi-syllabic words. The theoretical and clinical implications of the research outcomes are explored.

La dyslexie développementale est un trouble spécifique de l'apprentissage de la lecture qui affecte 3 à 7% des enfants d'âge scolaire. Il est bien établi aujourd'hui que la dyslexie découle en partie de variations génétiques qui causent des changements lors du développement cérébral, qui, à leur tour, ont des conséquences au niveau cognitif. Cette thèse s'appuie sur les analyses morphométriques de trois des sillons principaux du cerveau dans trois grands ensembles de données d'imagerie par résonance magnétique : 102 participants français, 80 participants polonais et 70 participants allemands, avec, dans chaque jeu de données, environ la moitié de participants ayant été diagnostiqués dyslexiques et la moitié de lecteurs normaux. J'ai étudié le sillon central, la scissure Sylvienne et le sillon temporal supérieur grâce aux outils de labellisation automatique et de mesures du logiciel BrainVISA. J'ai mesuré des propriétés quantitatives (surface et profondeur) ainsi que des propriétés qualitatives (configuration) de chaque sillon. J'ai montré une triple interaction entre groupe, sexe et hémisphère dans la profondeur moyenne du sillon central, laissant penser que les participants contrôles et dyslexiques diffèrent en terme d'asymétrie de profondeur de ce sillon. Comme la sulcation est un processus se déroulant de façon précoce lors du développement du cerveau et qui semble moins plastique que d'autres mesures cérébrales (comme, par exemple, les volumes de matière grise), ce résultat pourrait s'avérer être un marqueur précoce du risque de dyslexie plutôt que la conséquence de mauvaises capacités de lecture. / Developmental dyslexia is a specific disorder of reading acquisition that affects 3 to 7% of school-aged children. It is well established that dyslexia is partly caused by genetic variations whitch cause changes in brain development, whitch then have consequences at the cognitive level. This Ph.D thesis is based on morphometry analysis of three main sulci of the brain in three large databases of brain magnetic resonance images: 102 participants from France, 80 particpants from Poland and 70 participants from Germany, with, in each database, about half of participants were diagnosed with dyslexia and half of normal readers. I have studied the central sulcus, the Sylvian fissure and the superior temporal sulcus thanks to the automatic labelisation and measures tools in the BrainVISA software. I have measured some quantitative properties (surface and depth) as well as some qualitative ones (configuration) of each sulcus. I have shown a triple interaction between group, sex and hemisphere in the mean depth of the central sulcus. This result allows us to think that control and dyslexic participants may be different in terms of depth asymetry in this particular sulcus. Given that sulcation is an early process during brain development et that it seems to be less plastic than other brain measures (like, for example, grey matter volumes), this result may be an early marker of risk factors for dyslexia rather than a consequence of poor reading.

La lecture et l’écriture sont deux activités complexes qui contribuent à la réussite dans toutes les disciplines scolaires. Pour l’apprenti scripteur, et plus particulièrement pour l’élève qui éprouve des difficultés d’apprentissage (notamment l’élève dyslexique), l’apprentissage de l’orthographe représente un réel défi et nécessite souvent des années d’effort. Or, la connaissance du code orthographique constitue le socle sur lequel se construit la compétence orthographique. La reconnaissance et la production de mots écrits impliquent la mise en place d’un noyau de connaissances communes se rapportant aux connaissances orthographiques, c’est-à-dire aux connaissances rattachées aux propriétés phonologiques, morphologiques et visuelles du code orthographique. Ainsi, tout au long du développement de la compétence orthographique, le lecteur-scripteur doit notamment construire des représentations orthographiques de plus en plus stables et mieux définies qui tiennent compte de l’ensemble des propriétés du code orthographique. Des données empiriques récentes indiquent toutefois que les élèves dyslexiques, qui commettent davantage d’erreurs orthographiques de fusion et de segmentation de mots que les élèves sans difficulté à l’écrit, ne semblent pas disposer de représentations orthographiques précises des mots à orthographier, et plus spécifiquement de bonnes représentations du début et de la fin des mots. L’objectif général de cette étude est donc d’expliquer les erreurs orthographiques de frontières lexicales chez les élèves dyslexiques. Comme à notre connaissance, il n’existe pas de norme quant au développement des connaissances des frontières lexicales chez les élèves normo-lecteurs/scripteurs, le premier objectif spécifique est de décrire, de façon transversale et longitudinale, les performances d’élèves normo-lecteurs/scripteurs de la maternelle à la 4e année du primaire à des épreuves évaluant les connaissances des frontières lexicales (étude 1). La mise en place de cette référence développementale a permis de répondre au deuxième objectif spécifique qui est d’évaluer les connaissances des frontières lexicales d’élèves dyslexiques du primaire (étude 2). Pour évaluer les compétences en lecture et en production de mots, une épreuve de lecture de la batterie de tests du K-ABC et une dictée de mots insérés en contexte phrastique ont été proposées. Trois épreuves (décision lexicale, identification lexicale et permutation lexicale), variant en termes de degré de contraintes cognitives, ont été effectuées par tous les participants à l’oral et à l’écrit afin d’évaluer leurs connaissances des frontières lexicales. / Reading and writing are two complex activities that contribute to success in all school subjects. For apprentice writers, and particularly for students with learning difficulties (notably students with dyslexia), learning to spell represents a real challenge and often requires years of effort. To be successful, students require knowledge of the orthographic code, which is the foundation upon which spelling ability it built. To recognize and produce written words, students must develop a set of core skills that are linked to orthographic knowledge, including knowledge of the phonological, morphological and visual properties of the orthographic code. As their spelling skills develop, readers and writers must construct increasingly stable and better defined orthographic representations that reflect the properties of the orthographic code. However, recent empirical research has found that students with dyslexia, who tend to make more errors related to word merging and segmentation than students without writing difficulties, do not seem to have accurate orthographic representations of the words they are trying to spell, particularly of the beginnings and endings of words. Therefore, the general aim of this study is to explain spelling errors occurring at word boundaries in dyslexic children. To our knowledge, no typical trajectory of development has been established for normally-developing readers/writers with regards to knowledge of lexical boundaries. Therefore, using both cross-sectional and longitudinal analyses, this study’s first objective is to describe the performances of normally-developing reader and writers from kindergarten to grade 4 on tasks related to lexical boundary knowledge (Study 1). With this developmental reference having been established, the second study will evaluate lexical boundary knowledge in primary school students with dyslexia (study 2). To evaluate ability in reading and word production, a reading test from the K-ABC battery and a dictation task requiring students to insert words in the context of a sentence were administered. To evaluate knowledge of lexical boundaries, three tasks (a lexical decision task, a lexical identification task, and a lexical permutation task) were completed by all participants in oral and written form, each of which varied according to the level of cognitive constraint involved in completing the task.

Cette recherche avait pour objectif d’étudier les troubles cognitifs à l’origine de la dyslexie, et plus particulièrement le déficit d’apprentissage de paires associées (PAL) à composante verbale (input ou output). Tout d’abord, une étude longitudinale menée auprès d’enfants tout-venant pré-lecteurs et apprentis lecteurs a permis de mettre en évidence une contribution spécifique des PAL intermodales à l’efficience ultérieure en lecture/transcription. Les résultats de l’étude neuropsychologique indiquent pour leur part que les enfants dyslexiques présentent un déficit pour tous les types de PAL à composante verbale. Ce déficit apparait toucher à la fois la mémorisation des réponses, notamment verbales, et la mémorisation des liens entre les deux items. Il serait lié à un défaut de stockage de l’information et non à un problème de récupération et affecterait l’apprentissage des paires associées sans entraver leur rétention à long terme. / This research aimed to study the cognitive causes of dyslexia, particularly the paired associate learning (PAL) including a verbal component (input or output) deficit. First, a longitudinal study of normally developing pre-readers and beginning readers highlighted a specific contribution of intermodal PAL as predictors of later reading/transcription skills. As for the results of our neuropsychological study, they indicate that dyslexic children exhibit a deficit for all types of PAL with verbal component. This deficit appears to reach both the memorization of answers, especially verbal answers, and the storage of the mapping between the two items. It would be linked to an information storage failure but not to a recovery problem, and would affect the buildup of associations without impairing their long-term retention.

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