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.

L’objectif de ce travail de thèse était de mieux caractériser l’hétérogénéité de la dyslexie développementale et d’étudier les implications de cette hétérogénéité pour la remédiation de ce trouble d’acqusition de la lecture. L’Etude I met en évidence une hétérogénéité cognitive au sein d’une population d’enfants dyslexiques, qui pourtant ont un profil de lecture homogène de dyslexie mixte. Ce profil est classiquement interprété comme relevant d’un double déficit. Or nous montrons que la plupart de ces enfants présente en fait un déficit cognitif unique, soit phonologique, soit de l’empan visuo-attentionnel (VA). De plus, ces deux sous-groupes à déficit unique ont des profils de lecture très similaires lorsqu’ils sont directement comparés. Ces données suggèrent donc que la classification en sous-types basée sur les profils de lecture n’est pas pertinente pour identifier des sous-groupes cognitivement homogènes dans la population dyslexique. Dans l’Etude II, nous décrivons un cas de dyslexie avec trouble sélectif de la lecture des pseudo-mots. Ce profil est classiquement interprété comme reflétant un déficit phonologique. Or, le cas que nous décrivons présente un trouble de l’empan VA en l’absence de toute atteinte verbale ou phonologique. Cette étude confirme une relation entre trouble cognitif et profil de lecture complexe et non univoque. L’Etude III interroge plus spécifiquement les liens entre troubles de l’empan VA, de la conscience phonémique et de la perception catégorielle des phonèmes. Nous montrons que la conscience phonémique joue un rôle de médiation entre perception catégorielle et lecture, et que cette relation est indépendante des capacités d’empan VA. Ces données nous ont ainsi permis de mieux caractériser l’hétérogénéité cognitive de la population dyslexique. Dans les deux dernières études, nous nous sommes interrogés sur la prise en compte de cette hétérogénéité cognitive dans la remédiation de la dyslexie. L’Etude IV est une étude d’entrainement cognitif. Deux types d’entraînements ont été successivement proposés à des enfants dyslexiques : un entraînement à la perception catégorielle et un entraînement de l’empan VA. Nous avons étudié les effets de chacun de ces entraînements sur des sous-groupes qui présentent un trouble cognitif unique, soit phonologique, soit de l’empan VA. Les résultats montrent l’intérêt de proposer une remédiation ciblée sur le déficit cognitif sous-jacent. Cette étude a également des enjeux théoriques majeurs, puisqu’elle nous a permis d’interroger les relations de causalité entre ces déficits cognitifs sous-jacents et la dyslexie. Enfin, dans l’Etude V la méthode d’adaptation visuelle par saillance syllabique étudiée n’améliore pas la lecture des enfants dyslexiques. L’ensemble des ces études confirment l’hétérogénéité cognitive de la population dyslexique et l’importance de prendre en compte cette hétérogénéité dans les méthodes de remédiation qui peuvent être proposées. / The first aim of this doctoral thesis was to better understand the heterogeneity of developmental dyslexia focusing on the relationship between reading profiles and cognitive disorders. Our second purpose was to question the implications of cognitive heterogeneity for the remediation of developmental dyslexia. Study I revealed cognitive heterogeneity despite the homogeneous reading profile of the recruited population. Most children with a mixed reading profile typically interpreted as resulting from a double deficit, actually suffered from a single cognitive disorder, either a phoneme awareness or a visual attention (VA) span disorder. In addition, direct comparisons of these two cognitively distinct subgroups revealed very similar reading profiles. These findings suggest that the classification based on reading profiles is irrelevant to identify cognitively homogeneous subgroups in dyslexia. In Study II, we report the case study of a child with a selective pseudo-word reading disorder, a profile typically attributed to a phonological deficit. Contrary to this prediction however, we show that this dyslexic child shows preserved verbal and phonological skills but a VA span deficit. This finding again suggests the absence of one-to-one relationships between reading profiles and cognitive disorders. Study III more specifically explored the links between three types of cognitive deficits, namely the VA span disorder, the phoneme awareness deficit and the categorical perception disorder. Results show that phoneme awareness mediates the relationship between categorical perception and reading: poor categorical perception causes poor phoneme awareness, which in turn impacts reading performance. Poor VA span also impacts reading performance but independently of phoneme awareness and categorical perception. These findings are further evidence for the independent contribution of phonology and VA span to the reading outcome of dyslexic children. In Study IV, we assessed the longitudinal effects of two cognitive trainings. Dyslexic participants with a single phonological or a single VA span disorder were administered successively either a categorical perception then a VA span intervention, or the two trainings in the reverse order. At the clinical level, results show that intervention is more efficient when targeted on the underlying cognitive deficit. At the theoretical level, they question causal relationship between these cognitive deficit and dyslexia. Last, Study V explored the compensation power of a visual adaptation method using syllabic saliency. Results failed to show any positive effect of this method on reading performance. The overall findings support the cognitive heterogeneity of the dyslexic population and show that taking this issue into account is crucial to improve the effects of intervention programs.

Made available in DSpace on 2016-06-02T19:46:10Z (GMT). No. of bitstreams: 1 2801.pdf: 1211196 bytes, checksum: bd3556ff3d69ede1871701db0bd90b46 (MD5) Previous issue date: 2009-04-29 / Universidade Federal de Sao Carlos / The aim of this study was to evaluate the effects of instructional tutorship focused on book reading in students with developmental dyslexia and learning disability based on the proposals of Clay s Reading Recovery Program (1993). Among the specific objectives, the study aimed at characterizing the performance in percentage and identify the strategies related to reading and writing found in pre and post-testing of all groups involved in the research (with and without intervention) and compare, in pre and post-testing, the results of students with developmental dyslexia and learning disability. A group of twelve students participated in the study, and group I (DL) was subdivided into: GDL1 composed of three students with developmental dyslexia that participated in the intervention and GDL2 consisting of three students with developmental dyslexia that did not participate in the intervention. Group II (DA) was subdivided into GDA1 consisting of three students with learning disability that participated in the intervention and GDA2 consisting of three students with learning disability that did not participate in the intervention. The research presented the design: pretesting, tutorship, post-testing. The data were collected in sessions held in pre and post-testing with tasks of the Diagnostic Survey (Clay, 1993). The interventions, based on instructional tutorship, were performed in twelve individual sessions, once a week, lasting one hour each during the first semester of 2008. The results were analyzed in a descriptive way by the score in percentage of correct answers. Positive effects were verified on the teaching of strategies and the study also provides strong evidence that instructional tutorship focused on book reading gives students with developmental dyslexia and learning disabilities benefits with significant differences shown by the development of students who participated in interventions. However, the results of this study revealed that there was an improvement in the tasks that were observed and strategies that were trained in students with a learning disability when compared with students with developmental dyslexia. / O objetivo geral deste estudo foi verificar os efeitos da tutoria instrucional centrada na leitura de livros em escolares com dislexia do desenvolvimento e com distúrbio de aprendizagem baseada nas propostas do programa de recuperação de leitura de Clay (1993). Dentre os objetivos específicos, o estudo visou; caracterizar o desempenho em porcentagem e identificar as estratégias relacionadas a leitura e escrita observadas na pré e pós-testagem de todos os grupos envolvidos na pesquisa (com e sem intervenção) e comparar os resultados na pré e pós-testagem de escolares com quadro de dislexia do desenvolvimento e distúrbio de aprendizagem. Participaram deste estudo doze escolares, sendo o grupo I (DL) subdivido em: GDL1 composto por três escolares com dislexia do desenvolvimento submetidos à intervenção, e GDL2, composto por três escolares com dislexia do desenvolvimento não submetidos à intervenção. O grupo II (DA), subdividido em GDA1, composto por três escolares com distúrbio de aprendizagem submetidos as sessões de intervenção e GDA2, composto por três escolares com distúrbio de aprendizagem não submetidos. A pesquisa apresentou o desenho: prétestagem, tutoria, pós-testagem. Os dados foram coletados nas sessões realizadas na pré e pós-testagem em tarefas do Levantamento Diagnóstico (Clay, 1993) As intervenções, baseada na tutoria instrucional, foram realizadas em doze sessões individuais, uma vez por semana e com duração de uma hora cada, durante o primeiro semestre de 2008. Os resultados foram analisados de forma descritiva pela pontuação obtida em porcentagem de acertos. Foram verificados efeitos positivos em relação ao ensino de estratégias, bem como o estudo fornece fortes indícios de que a tutoria instrucional centrada na leitura de livros propicia aos alunos com dislexia do desenvolvimento e distúrbio de aprendizagem benefícios com diferença relevantes demonstrada pelo desenvolvimento dos alunos que participaram das intervenções. Porém, os resultados deste estudo revelaram que houve uma melhora nas tarefas observadas e nas estratégias treinadas nos alunos com distúrbio de aprendizagem quando comparados com os escolares com dislexia do desenvolvimento.

Made available in DSpace on 2016-03-15T19:41:23Z (GMT). No. of bitstreams: 1 Darlene Godoy de Oliveira.pdf: 3172504 bytes, checksum: 95d543d037f25f72c573d89ce7ccd732 (MD5) Previous issue date: 2014-07-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Developmental Dyslexia has a main deficit the effective word recognition, which is a complex cognitive processing due perceptual skills, language and later stages of syntactic and semantic integration. Among the wide range neurobiological evidence related this disorder in childhood and across life-span, event-related potential measures indicates differentiated pattern in amplitudes, latencies and hemispheric processing in different stages of sensory/perceptual, orthographic, phonologic and semantic processing. These electrophysiological evidences are related to behavioral deficits and to reading compensatory mechanisms in Dyslexia. The present thesis aimed to verify and compare the behavioral and electrophysiological pattern of adults (Study 1) and children and adolescents (Study 2) with and without Dyslexia during a Lexical Decision task. The sample of Study 1 comprised by 20 dyslexics and 23 normal readers with college degree. In Study 2, twenty dyslexic children and adolescents and twenty normal readers were included. All participants were matched for gender, age and educational level and performed a battery of intelligence, reading, writing and phonological awareness tasks. The lexical decision task was composed by regular high frequency words in Brazilian Portuguese, quasi-words derived from real words and pseudowords not derived from real words. Behavioral results in both studies revealed that dyslexics had worse accuracy and increased reaction times in all lexical categories. ERPs analysis of Study 1 indicated greater amplitudes in right P100 for both groups. The N170, N400 and LPC were reduces on the left hemisphere for dyslexics. N400 and LPC were higher for words and quasi-words, stimuli that are represented on orthographic and phonological lexicon. Correlations data in all sample verified reduced N170 and LPC left amplitudes associated with good performance in behavioral reading, writing and phonological awareness tests. GD with slow behavioral performance exhibited higher N170 and N400 on left hemisphere. Study 2 results indicated greater P100 on right hemisphere for all lexical categories in all sample, and reduced for DG. N170 were higher at left side and for quasi-words. N400 were higher for words and quasi-words, as well reduced in left hemisphere for DG. LPC were higher in left hemisphere for pseudowords and reduced in dyslexics. Correlational results revealed reduced left N170, N400 and LPC in dyslexics with slow behavioral performance. Controls with slow performance exibithed higher P100 amplitudes, as well higher left N400 if they had higher reading skills. Generally, ERP analysis indicated lacks of hemispheric specialization in dyslexics. The absence of ERP group differences on Study 2 can be related to developmental reading fluency processes, although we verified positive correlations between higher linguistic ERP amplitudes and better behavioral performances for both children and adults. We conclude that dyslexic children and adults present differenciated ERP amplitudes and hemispheric distribution during reading in Brazilian Portuguese. / A Dislexia do Desenvolvimento tem como déficit principal o reconhecimento eficaz de palavras, sendo este um processamento cognitivo complexo. Dentre as evidências neurobiológicas do transtorno, disléxicos apresentam alterações nos potenciais relacionados a eventos durante o reconhecimento de palavras, com padrão diferenciado de latência, amplitude e processamento hemisférico nos estágios sensório/perceptual, ortográfico, fonológico e semântico. Estes indicam déficits no processamento eletrofisiológico e uso de mecanismos compensatórios de leitura. Esta tese objetivou mensurar e comparar o padrão comportamental e eletrofisiológico de adultos (Estudo 1) e crianças e adolescentes (Estudo 2) com e sem Dislexia do Desenvolvimento durante uma tarefa de decisão lexical. Participaram do Estudo 1 vinte universitários disléxicos e vinte e três adultos bons leitores. Participaram do Estudo 2 vinte crianças e adolescentes disléxicos e vinte controles bom leitores. Os participantes foram pareados por sexo, idade e nível de escolaridade e realizaram uma bateria de testes de inteligência, leitura, escrita e consciência fonológica. A tarefa de decisão lexical foi composta por palavras regulares de alta frequência no português brasileiro, quase-palavras derivadas de palavras reais e pseudopalavras não derivadas. Os resultados comportamentais da tarefa de decisão lexical nos estudos indicaram pior acurácia, maior omissão e lentidão no julgamento dos itens de todas as classes lexicais pelos disléxicos. Análises dos ERPs no Estudo 1 indicaram maior amplitude do P100 no hemisfério direito em ambos os grupos. Os potenciais N170, N400 e LPC foram reduzidos no hemisfério esquerdo dos disléxicos. O N400 e o LPC foram mais pronunciados nas palavras e quase-palavras, estímulos com representação no léxico fonológico e ortográfico. Correlações com os dados da amostra total; indicaram menores amplitudes N170 e LPC no hemisfério esquerdo associadas à alta acurácia nos testes comportamentais de leitura, escrita e consciência fonológica, enquanto que no GD, o N170 e o N400 foram mais pronunciados no hemisfério esquerdo dos sujeitos mais lentos nas tarefas. Análises do Estudo 2 indicaram P100 maior no hemisfério direito em todas as categorias lexicais nos dois grupos, e reduzido no GD. O N170 tendeu a ser mais pronunciado no hemisfério esquerdo e nas quase-palavras. O N400 foi maior nas palavras e quase-palavras, sendo reduzido no hemisfério esquerdo do GD. O LPC foi maior no hemisfério esquerdo para as pseudopalavras e foi reduzido no GD. Foram encontradas correlações negativas entre amplitudes do N170, N400 e LPC esquerdo nos disléxicos com o tempo de execução nas tarefas comportamentais. No GC, o P100 foi maior nos sujeitos mais lentos e houve associação positiva dasamplitudes do N400 esquerdo e acurácia na leitura. No geral, as análises dos ERPs nos experimentos indicam déficits de especialização hemisférica em disléxicos. Ausências de diferenças entre os grupos do Estudo 2 nos ERPs analisados podem estar relacionadas a fatores desenvolvimentais da leitura, embora tanto em crianças como em adultos disléxicos já haja associação positiva entre bom desempenho comportamental e maiores amplitudes nos ERPs linguísticos. Conclui-se que crianças e adultos disléxicos apresentam padrão diferenciado de amplitudes e distribuição hemisférica em distintos ERPs durante a leitura no Português Brasileiro.

Developmental dyslexia is a specific reading and spelling disability with several explanatory proposals. Previous research has shown that there is a strong relation between developmental dyslexia and difficulties in phonological processing, which has resulted in the theory that the cause of developmental dyslexia is a specific weakness in phonological awareness. However, such a specific weakness does not explain the non-linguistic difficulties that are also common in developmental dyslexia. According to the Procedural Deficit Hypothesis (PDH), several (both linguistic and non-linguistic) difficulties that are observed in developmental dyslexia can be explained by abnormal development of the procedural memory system. Moreover, this hypothesis implies that the declarative memory system remains intact and may have a compensatory role for the reading disabilities in developmental dyslexia. In this study, the aspect of declarative memory that is visual recognition memory after incidental encoding was examined. 10 children with diagnosed developmental dyslexia and 10 typically developed children participated in the study. The results indicated an intact declarative memory in children with developmental dyslexia. However, no significant correlation between declarative memory and reading ability was found. Thus, the prediction that declarative memory can serve a compensatory role in developmental dyslexia was not supported. / Dyslexi är en specifik läs- och skrivsvårighet med flera förklaringsmodeller. Tidigare forskning har visat på ett starkt samband mellan dyslexi och svårigheter med fonologiskt processande, vilket har lett fram till hypotesen att orsaken till dyslexi är en specifik svaghet i fonologisk medvetenhet. En sådan specifik nedsättning kan dock inte förklara de icke-språkliga svårigheter som också är vanligt förekommande vid dyslexi. Enligt the procedural deficit hypothesis (PDH) kan många (både språkliga och icke-språkliga) svårigheter vid dyslexi förklaras av en nedsättning i det procedurella minnet. Vidare innebär hypotesen att det deklarativa minnet är intakt och kan fungera som kompensation för svårigheterna vid dyslexi. I denna studie undersöktes det deklarativa minnet i form av visuellt igenkänningsminne efter oavsiktlig inkodning. I studien deltog 10 barn med dyslexi och 10 barn utan dyslexi. Resultatet indikerade att det deklarativa minnet var intakt hos barnen med dyslexi. Däremot kunde inget signifikant samband mellan deklarativt minne och läsförmåga ses. Antagandet att deklarativt minne kan fungera som kompensation vid dyslexi kunde därför inte stödjas.

Dans le cadre des travaux sur le rôle des connaissances phonologiques dans le processus de reconnaissance de mot écrit, l’objectif de notre thèse est de contribuer à mieux décrire la nature du code impliqué et de comprendre les mécanismes par lesquels les connaissances phonologiques interviennent en lecture. Nous voudrions avant tout défendre l’idée selon laquelle les premières étapes du processus de reconnaissance de mot écrit impliquent un code phonologique suffisamment fin pour être décrit en termes de traits phonologiques, en montrant que les lecteurs sont sensibles à des aspects infra-phonémiques et qu’il existerait une organisation hiérarchique de ces traits. D’autre part, cette thèse vise à apporter des arguments en faveur de l’existence de troubles phonologiques chez les enfants dyslexiques, à préciser certaines anomalies de leurs représentations au niveau infra-phonémique, tout en tenant compte de disparités possibles dans ces anomalies selon le type de dyslexie.Nous présenterons en premier lieu le cadre théorique et les travaux expérimentaux en psychologie cognitive et psycholinguistique nous conduisant à formuler des questions précises à ce propos. La présentation de travaux réalisés en linguistique et en neuropsychologie étayera les hypothèses que nous proposerons ensuite. Dans la partie théorique, nous présenterons notamment une proposition de modèle de lecture articulant deux mécanismes basés sur les traits phonologiques et l’orientation de nos hypothèses sera guidée par les contraintes de ce modèle.Une démarche expérimentale sera développée en plusieurs étapes pour apporter des données comportementales permettant de discuter nos hypothèses à propos d’adultes bons lecteurs, d’enfants présentant un développement ordinaire et d’enfants dyslexiques. / Some studies in literature show the involvement of phonological knowledge in printed words processing. The goal of this work is to contribute to describe the nature of the code involved in printed word recognition, and to understand the mechanisms of phonological knowledge involvement in reading. We firstly want to show that the early steps of printed words recognition involve a phonological code described in terms of phonological features, by showing that skilled readers are sensitive to infra-phonemic elements and that a hierarchical organisation of these features could exist. Otherwise, this work aims to provide clues in favour of the existence of phonological impairments in dyslexic children, to define some deficits of their infra-phonemic organisation, and to show that these deficits could be different according to the type of developmental dyslexia. On the one hand, we present the theory and the experimental studies in cognitive psychology and in psycholinguistics that lead us to some questions. On the other hand, the presentation of studies in linguistics and in neuropsychology provide clues in favour of our hypothesis. In the theorical part, we present a reading model that involve two reading mechanisms based on phonological features, and our hypothesis allow us to test this model. Our experimental word is developped in several steps to provide behavior data that lead us to discuss our hypothesis about adult skilled readers, normal reading children, and dyslexic chilmdren.

Made available in DSpace on 2016-04-04T18:28:12Z (GMT). No. of bitstreams: 1 RAUNI JANDE ROAMA ALVES.pdf: 1597487 bytes, checksum: 2c5fc0e1ecfc2b3e4750ae14cfbd068e (MD5) Previous issue date: 2013-12-13 / Pontif?cia Universidade Cat?lica de Campinas / Dyslexia is a disorder resulting from neuropsychological dysfunction and mostly causes difficulties in learning to read. International studies speculate that this framework does not only involve deficient cognitive skills, but also well developed, such as creativity. Starting from this hypothesis, the present study aimed to compare the creativity of children with dyslexia (GC) with children without difficulties in reading and writing (GN). It was also investigated how the intelligence is related to that performance in both groups. The GC was recruited at the Clinical Hospital of the State University of Campinas (UNICAMP) and the GN in a regular school of the state of S?o Paulo. It was investigated 13 children in each group, ranging in age from eight years to 11 years and eight months (GC: M=10,92+1,03; GN: M=10,61+0,50), with five females and eight males in group GC and nine females and four males in group GN. To survey the creativity was used the "Test of Figural Creativity for Children (TCFI) and for intelligence was administered the test "Raven Coloured Progressive Matrices (MPCR)", "Human Figure Drawing (DFH)" and "Wechsler Intelligence Scale for Children - third version (WISC-III)", the latter two only in GC. For the selection of the GN was used a questionnaire for parents and a semistructured interview for teachers to eliminate diagnostic criteria for dyslexia, besides the "Academic Performance Test", with the aim of selecting children with reading and writing performance expected for age and grade. The results showed no statistically significant differences between both groups in creativity. However, the GC had a lower average than the GN in the total TCFI, while also showed higher scores for 18 of the 31 characteristics evaluated by it. High correlation was observed between the MPCR and the TCFI in both groups and no significant correlations between the DFH and the WISC-III with the TCFI in GC. Some hypotheses have been formulated: the existence of possible relationships between creativity and executive functions, the latter being to the detriment of individuals with dyslexia, which could explain the result of the total TCFI; the influence of emotional and possibly aspects of personality that are characteristic of dyslexia, which could explain the better performance in the majority of the characteristics evaluated in TCFI. There was no pattern in the correlations between measures of intelligence and creativity in both investigated groups, as found in the literature. It is concluded that this study provided important findings for early clarification on a possible relationship between creativity and dyslexia, however, considering the complexity of both constructs, studies involving the investigation of their relations with other psychological variables as well as expansion and diversification of the sample are needed. / A dislexia ? um transtorno decorrente de disfun??es neuropsicol?gicas e acarreta principalmente dificuldades no aprendizado da leitura. Estudos internacionais especulam que esse quadro n?o somente envolveria habilidades cognitivas deficit?rias, mas tamb?m bem desenvolvidas, como a criatividade. Partindo-se dessa hip?tese, o presente estudo objetivou comparar a criatividade de crian?as com dislexia (GC) com o de crian?as sem dificuldades em leitura e escrita (GN). Tamb?m se investigou a rela??o entre criatividade e intelig?ncia em ambos os grupos. O GC foi recrutado no Hospital de Cl?nicas da Universidade Estadual de Campinas (UNICAMP) e o GN em uma escola de ensino regular de uma cidade do interior de S?o Paulo. Foram investigadas 13 crian?as em cada grupo, com faixa et?ria de oito anos a 11 anos e oito meses (GC: M=10,92+1,03; GN: M=10,61+0,50), sendo cinco do sexo feminino e oito do masculino no GC e nove do sexo feminino e quatro do masculino no GN. Para a avalia??o da criatividade foi utilizado o Teste de Criatividade Figural Infantil (TCFI) e para intelig?ncia foram administrados os testes Matrizes Progressivas Coloridas de Raven (MPCR) , Desenho da Figura Humana (DFH) e Escala de Intelig?ncia Wechsler para crian?as (WISC-III) , sendo os dois ?ltimos somente no GC. Para a sele??o do GN foi utilizado um question?rio para os pais e uma entrevista semiestruturada para os professores a fim de eliminar crit?rios diagn?sticos para dislexia, al?m do Teste de Desempenho Escolar , com o objetivo de selecionar somente aquelas crian?as que apresentassem desempenho em leitura e em escrita esperado para a idade e s?rie. Os resultados encontrados n?o evidenciaram diferen?as estat?sticas significativas entre ambos os grupos na medida de criatividade. No entanto, o GC apresentou menor m?dia em rela??o ao GN no total do TCFI, ao mesmo tempo em que tamb?m apresentou m?dias mais altas em 18 das 31 caracter?sticas avaliadas por esse mesmo teste. Foi verificada alta correla??o entre os testes MPCR e o TCFI em ambos os grupos e correla??es n?o significativas entre o DFH e o WISC-III com o TCFI no GC. Algumas hip?teses foram elaboradas: a exist?ncia de poss?veis rela??es entre criatividade e fun??es executivas, sendo essas ?ltimas em preju?zo em sujeitos com dislexia, que poderia explicar o resultado obtido no total do TCFI; a influ?ncia de aspectos emocionais e possivelmente de personalidade, caracter?sticos a dislexia, que poderiam explicar o melhor desempenho obtido na maioria das caracter?sticas avaliadas no TCFI. N?o foi verificado um padr?o nas correla??es entre as medidas de intelig?ncia e de criatividade em ambos os grupos investigados, assim como encontrado na literatura. Conclui-se que o presente estudo forneceu achados importantes para o in?cio do esclarecimento sobre uma poss?vel rela??o entre criatividade e dislexia, no entanto, considerando a complexidade de ambos os constructos, estudos que envolvam a investiga??o de suas rela??es com outras vari?veis psicol?gicas bem como amplia??o e diversifica??o da amostra se fazem necess?rios.

Ce travail de thèse porte essentiellement sur le cervelet. Nous y suivons deux axes majeurs : en termes de fonctions cérébelleuses, nous nous intéressons à l’apprentissage et l’adaptation du contrôle moteur ; en termes de dysfonctions cérébelleuses, nous nous intéressons à la dyslexie développementale.Nous nous orientons vers l’apprentissage du contrôle moteur afin d’en proposer un modèle computationnel fonctionnel appliqué aux mouvements oculaires volontaires. Pour ce faire, la Logique Floue est un de nos outils précieux. Nous avons proposé deux modèles. Le premier, AFCMAC (Auto-adaptive Fuzzy Cerebellar Model Articulation Controller), le résultat de l’intégration de la Logique Floue dans l’architecture de CMAC (Cerebellar Model Articulation Controller), est pourvu d’améliorer la vitesse/durée d’apprentissage et le besoin en termes de mémoire par rapport à CMAC. Le second modèle est CMORG (fuzzy logiC based Modeling for Oculomotor contRol LearninG), dont sa structure est également basée sur la Logique Floue, et dans lequel, le réseau de neurones est utilisé comme la mémoire pour gérer les règles Floues. Les résultats des évaluations des modèles proposés (AFCMAC et CMORG) et étudiés (CMAC et FCMAC – Fuzzy Cerebellar Model Articulation Controller), via les données oculomotrices des groupes d’enfants dyslexiques et contrôles lors de la lecture, montrent que CMORG est le plus performant à la fois, en termes de vitesse/durée d’apprentissage et également, de consommation de mémoire. Un autre avantage principal de CMORG par rapport aux autres modèles, est son interprétabilité par les experts.Concernant la dyslexie développementale, nous avons mené une étude expérimentale sur les déficits du contrôle moteur binoculaire lors des saccades des six enfants dyslexiques pendant les deux tâches différentes (la lecture d’un texte et la visualisation des chaînes de caractères) et dans les deux distances de vision (40 cm et 100 cm). Nous corroborons et adhérons à l’idée que la (mauvaise) qualité de la coordination binoculaire des saccades chez les enfants dyslexiques est indépendante des difficultés en lecture, associée peut-être aux hypothèses du déficit du magnosystème et du dysfonctionnement cérébelleux. / This thesis focuses on the cerebellum. We follow two main lines: in terms of cerebellar functions, we are interested in learning and adaptation motor control ; in terms of cerebellar dysfunctions, we are interested in developmental dyslexia.We focus on learning motor control in order to provide a functional computational model applied to voluntary eye movements. To this end, Fuzzy Logic is one of our valuable tools. We proposed two models. The former is AFCMAC (Auto-adaptive Fuzzy Cerebellar Model Articulation Controller), the result of the integration of Fuzzy Logic in CMAC (Cerebellar Model Articulation Controller) architecture, in order to improve learning speed/time and memory requirements compared to the CMAC. The latter is CMORG (fuzzy logiC based Modeling for Oculomotor contRol LearninG), whose structure is also based on Fuzzy Logic, and in which, the neural network is used as the memory to handle Fuzzy rules. The evaluation results of the proposed (AFCMAC and CMORG) and studied (CMAC and FCMAC – Fuzzy Cerebellar Model Articulation Controller) models via oculomotor data of dyslexic and control groups while reading show that CMORG is the most efficient both in terms of learning speed/time and also memory consumption. Another main advantage of CMORG over the other models is its interpretability by experts. Regarding the developmental dyslexia, we conducted an experimental study on binocular motor control deficits during saccades in six dyslexic children while two different tasks (text reading and character string scanning) and in two viewing distances (40 cm and 100 cm). We corroborate and adhere to the idea that the (bad) quality of binocular coordination of saccades in dyslexic children is independent of reading difficulties, maybe associated with magnosystem and cerebellar deficit hypothesis.

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The ability to read proficiently is key to social participation and an important premise for individual well-being and vocational success. Individuals with developmental dyslexia, a highly prevalent neurodevelopmental disorder affecting hundreds of millions of children and adults worldwide, face severe and persistent difficulties in attaining adequate reading levels. Despite years of extensive research efforts to elucidate the neurobiological origin of this disorder, its exact etiology remains unclear to date. In this context, most neuroimaging research on dyslexia in humans has focused on the cerebral cortex and has identified alterations in a distributed left-lateralized cortical language network. However, pioneering post-mortem human studies and animal models suggest that dyslexia might also be associated with alterations in subcortical sensory thalami and early sensory pathways. The largely cortico-centric view of dyslexia is due in part to considerable technical challenges in assessing the human sensory thalami non-invasively using conventional magnetic resonance imaging (MRI). As a result, the role that sensory thalami may play in dyslexia has been largely unaddressed. In this dissertation, I leveraged recent advances in high-field MRI to investigate the role of the human lateral geniculate nucleus (LGN) of the visual thalamus in adults with dyslexia in-vivo. In three multi-modal high-field MRI studies, I show that (i) dyslexia is associated with structural alterations in the direct V1-bypassing white matter pathway connecting the LGN with cortical motion-sensitive area V5/MT in the left hemisphere; (ii) the connectivity strength of which predicts a core symptom of the disorder, i.e., rapid naming ability. I further demonstrate that (iii) the two major functional subdivisions of the LGN can be distinguished non-invasively based on differences in tissue microstructure; and that (iv) adults with dyslexia show functional response alterations specifically in the magnocellular subdivision of the LGN. I also demonstrate that this subdivision deficit (v) is more pronounced in male than female dyslexics; and (vi) predicts rapid naming ability in male dyslexics only. The results of this doctoral thesis are the first to confirm previous post-mortem evidence of LGN alterations in dyslexia in-vivo and point to their relevance to key symptoms of the disorder. In synergy, our research findings offer new perspectives on explanatory models of dyslexia and bear potential implications also for prospective treatment strategies.:Contribution Statement i Acknowledgments iii Abstract v Table of Contents vii 1 General Introduction 1 1.1 Developmental Dyslexia 1 1.1.1 Diagnostic Criteria 1 1.1.2 Prevalence and Etiology 2 1.1.3 Cognitive and Behavioral Symptoms 3 1.1.4 Explanatory Models in Cognitive Neuroscience 4 1.2 Lateral Geniculate Nucleus 7 1.2.1 Anatomy and Function 7 1.2.2 Technical Challenges in Conventional MRI 8 1.2.3 High-Field MRI 9 1.3 Research Aim and Chapter Outline 10 2 Altered Structural Connectivity of the Left Visual Thalamus in Developmental Dyslexia 13 2.1 Summary 14 2.2 Results and Discussion 15 2.3 Conclusions 22 2.4 Materials and Methods 23 2.4.1 Subject Details 23 2.4.2 High-Resolution MRI Acquisition and Preprocessing 23 2.4.3 Lateral Geniculate Nucleus Definition 24 2.4.4 Cortical Region of Interest Definition 26 2.4.5 Probabilistic Tractography 27 2.4.6 Quantification and Statistical Analysis 29 2.5 Supplementary Information 30 3 Mapping the Human Lateral Geniculate Nucleus and its Cytoarchitectonic Subdivisions Using Quantitative MRI 33 3.1 Abstract 34 3.2 Introduction 35 3.3 Materials and Methods 37 3.3.1 In-Vivo MRI 37 3.3.2 Post-Mortem MRI and Histology 41 3.4 Results 44 3.4.1 Lateral Geniculate Nucleus Subdivisions in In-Vivo MRI 44 3.4.2 Lateral Geniculate Nucleus Subdivisions in Post-Mortem MRI 46 3.5 Discussion 50 3.6 Supplementary Information 54 3.6.1 In-Vivo MRI 54 3.6.2 Post-Mortem MRI and Histology 58 3.6.3 Data and Code Availability 60 4 Dysfunction of the Visual Sensory Thalamus in Developmental Dyslexia 61 4.1 Abstract 62 4.2 Introduction 63 4.3 Materials and Methods 66 4.3.1 Subject Details 66 4.3.2 High-Resolution MRI Experiments 66 4.3.3 High-Resolution MRI Acquisition and Preprocessing 67 4.3.4 Lateral Geniculate Nucleus Definition 68 4.3.5 Quantification and Statistical Analysis 69 4.4 Results 70 4.5 Discussion 75 4.6 Supplementary Information 77 4.6.1 Supporting Methods 77 4.6.2 Supporting Results 81 4.6.3 Data and Code Availability 82 5 General Conclusion 83 5.1 Summary of Research Findings 83 5.2 Implications for Dyslexia Models 84 5.2.1 Phonological Deficit Hypothesis 84 5.2.2 Magnocellular Theory 84 5.2.3 Model According to Ramus 85 5.2.4 Need for Revised Model 86 5.3 Implications for Remediation 87 5.4 Research Prospects 88 5.5 Brief Concluding Remarks 90 6 Bibliography 91 7 List of Tables 113 8 List of Figures 115 9 Selbstständigkeitserklärung 117