MorphoTELEQ : élaboration d’un test évaluant la conscience morphologique chez les enfants québécois de la 1re à la 6e année du primaire

Essai doctoral présenté à la Faculté des études supérieures en vue de l’obtention du grade de Doctorat en psychologie (D. Psy.) - option neuropsychologie clinique.Au courant des dernières décennies, la conscience morphologique a suscité l’intérêt de plusieurs chercheurs et intervenants puisqu’elle semble influencer l’apprentissage de la lecture et de l’écriture. Toutefois, aucun outil standardisé n’est actuellement disponible en français pour évaluer la conscience morphologique chez les enfants du primaire. L’objectif de cette étude est de créer et pré-valider un test visant à évaluer cette habileté métalinguistique chez les élèves franco-québécois : le MorphoTELEQ. Ce test administré à l’oral est composé de cinq épreuves permettant d’évaluer les connaissances relationnelles, syntaxiques et distributionnelles acquises par l’enfant en morphologie dérivationnelle. Lors de la sélection des items du test, la fréquence lexicale, la productivité des affixes, la transparence de la relation morphologique, la complexité de la structure syllabique et les familles de mots ont été prises en considération. Trois experts ont ensuite été invités à se prononcer sur la méthodologie et la pertinence du choix des épreuves afin d’en valider le contenu. La version révisée a ensuite été administrée à 13 élèves normolecteurs de la 1re à la 6e année du primaire. À la lumière de la performance de ces élèves, la sélection des items, leur niveau de difficulté et la formulation des consignes d’administration ont été peaufinés et finalisés Le MorphoTELEQ pourra ainsi être validé auprès d’un échantillon représentatif des élèves franco-québécois afin d’en vérifier les qualités psychométriques et d’obtenir des normes correspondant à chaque niveau scolaire. Nous pensons que cet outil contribuera à mieux caractériser le développement de la conscience morphologique chez élèves franco-québécois du primaire ayant ou non des difficultés d’apprentissage en langage écrit, ainsi qu’à mieux orienter les interventions auprès de ces jeunes apprenants.In the last decades, morphological awareness has aroused the interest of researchers and professionals as it seems to influence the acquisition of literacy. However, no standardized tool is actually available in French to assess morphological awareness in elementary school children. This study aims to create and pre-validate a test assessing that metalinguistic ability in French-speaking Quebecer students : the MorphoTELEQ. This oral test consists of five tasks assessing the relational, syntactic, and distributional knowledge acquired by children in derivational morphology. During item selection, lexical frequency, affix productivity, opacity of the morphological relation, syllable structure complexity, and word families were considered. In order to validate the content, three experts were invited to comment on the methodology and the choice of tasks to be administered. The revised version was subsequently completed by 13 students from 1st to 6th grade without difficulties in written language. After reviewing the student’s performances, the item selection, level of difficulty and instructions wording were refined and finalised. Validation of the MorphoTELEQ can therefore be completed with a representative sample of French-speaking Quebecer students to verify its psychometric qualities and establish the norms for each grade. We think that this tool will contribute to better describe the development of morphological awareness in the French-speaking elementary school students in Quebec with and without difficulties in written language, and to help guide interventions for this pediatric population

Neural changes associated with semantic processing in healthy aging despite intact behavioral performance

Semantic memory recruits an extensive neural network including the left inferior prefrontal cortex (IPC) and the left temporoparietal region, which are involved in semantic control processes, as well as the anterior temporal lobe region (ATL) which is considered to be involved in processing semantic information at a central level. However, little is known about the underlying neuronal integrity of the semantic network in normal aging. Young and older healthy adults carried out a semantic judgment task while their cortical activity was recorded using magnetoencephalography (MEG). Despite equivalent behavioral performance, young adults activated the left IPC to a greater extent than older adults, while the latter group recruited the temporoparietal region bilaterally and the left ATL to a greater extent than younger adults. Results indicate that significant neuronal changes occur in normal aging, mainly in regions underlying semantic control processes, despite an apparent stability in performance at the behavioral level

Integrated systems research for sustainable smallholder agriculture in the Central Mekong: Achievements and challenges of implementing integrated systems research

Internal Revie

A MEG study of the neural substrates of semantic processing in semantic variant primary progressive aphasia

Despite a well-documented pattern of semantic memory (SM) impairment, the patterns of brain activation during semantic processing in svPPA still remain poorly understood. The current study aimed to investigate the neural substrates of residual semantic processing in the context of this significant but selective SM impairment, through the case study of one svPPA patient. One svPPA patient (EC) and six elderly controls carried out a general-level semantic categorization task (biological and manufactured objects) while their brain activity was recorded using magnetoencephalography (MEG). Despite similar behavioral performance, EC showed hyperactivation of the left inferior temporal gyrus (ITG) and right anterior temporal lobe (ATL) relative to controls. This suggests that periatrophic regions within the ATL region may support preserved semantic abilities in svPPA. These results thus contribute to our understanding of the brain regions which are recruited to compensate for bilateral atrophy of the ATL and ensure residual semantic processing in svPPA

Functional changes in the cortical semantic network in amnestic mild cognitive impairment

Semantic memory impairment has been documented in older individuals with amnestic Mild cognitive impairment (aMCI), who are at risk of developing Alzheimer’s disease (AD), yet little is known about the neural basis of this breakdown. The main objective of this study was to investigate the brain mechanisms associated with semantic performance in patients with aMCI. Method: A group of aMCI patients and a group of healthy older controls carried out a semantic categorization task while their brain activity was recorded using magnetoencephalography (MEG). During the task, participants were shown famous faces and had to determine whether each famous person matched a given occupation. The main hypotheses were that: (i) semantic processing should be compromised for aMCI patients, and (ii) these deficits should be associated with cortical dysfunctions within specific areas of the semantic network. Results: Behavioural results showed that aMCI participants were significantly slower and less accurate than control participants at the semantic task, corroborating previous reports. Additionally, relative to controls, a significant pattern of hyperactivation was found in the aMCI group within specific regions of the semantic network, including the right anterior temporal lobe and inferior prefrontal cortex. Conclusions: Abnormal functional activation within key areas of the semantic network suggests that it is compromised early in the disease process. Moreover, this pattern of increased activation in aMCI was positively associated with grey matter integrity in specific areas, but was not associated with any specific pattern of atrophy, suggesting that functional hyperactivation may precede atrophy of the semantic network in aMCI

Lipid-Induced Peroxidation in the Intestine Is Involved in Glucose Homeostasis Imbalance in Mice

BACKGROUND: Daily variations in lipid concentrations in both gut lumen and blood are detected by specific sensors located in the gastrointestinal tract and in specialized central areas. Deregulation of the lipid sensors could be partly involved in the dysfunction of glucose homeostasis. The study aimed at comparing the effect of Medialipid (ML) overload on insulin secretion and sensitivity when administered either through the intestine or the carotid artery in mice. METHODOLOGY/PRINCIPAL FINDINGS: An indwelling intragastric or intracarotid catheter was installed in mice and ML or an isocaloric solution was infused over 24 hours. Glucose and insulin tolerance and vagus nerve activity were assessed. Some mice were treated daily for one week with the anti-lipid peroxidation agent aminoguanidine prior to the infusions and tests. The intestinal but not the intracarotid infusion of ML led to glucose and insulin intolerance when compared with controls. The intestinal ML overload induced lipid accumulation and increased lipid peroxidation as assessed by increased malondialdehyde production within both jejunum and duodenum. These effects were associated with the concomitant deregulation of vagus nerve. Administration of aminoguanidine protected against the effects of lipid overload and normalized glucose homeostasis and vagus nerve activity. CONCLUSIONS/SIGNIFICANCE: Lipid overload within the intestine led to deregulation of gastrointestinal lipid sensing that in turn impaired glucose homeostasis through changes in autonomic nervous system activity

CBP-HSF2 structural and functional interplay in Rubinstein-Taybi neurodevelopmental disorder

Rubinstein-Taybi syndrome (RSTS) is a neurodevelopmental disorder with unclear underlying mechanisms. Here, the authors unravel the contribution of a stress-responsive pathway to RSTS where impaired HSF2 acetylation, due to RSTS-associated CBP/EP300 mutations, alters the expression of neurodevelopmental players, in keeping with hallmarks of cell-cell adhesion defects.Patients carrying autosomal dominant mutations in the histone/lysine acetyl transferases CBP or EP300 develop a neurodevelopmental disorder: Rubinstein-Taybi syndrome (RSTS). The biological pathways underlying these neurodevelopmental defects remain elusive. Here, we unravel the contribution of a stress-responsive pathway to RSTS. We characterize the structural and functional interaction between CBP/EP300 and heat-shock factor 2 (HSF2), a tuner of brain cortical development and major player in prenatal stress responses in the neocortex: CBP/EP300 acetylates HSF2, leading to the stabilization of the HSF2 protein. Consequently, RSTS patient-derived primary cells show decreased levels of HSF2 and HSF2-dependent alteration in their repertoire of molecular chaperones and stress response. Moreover, we unravel a CBP/EP300-HSF2-N-cadherin cascade that is also active in neurodevelopmental contexts, and show that its deregulation disturbs neuroepithelial integrity in 2D and 3D organoid models of cerebral development, generated from RSTS patient-derived iPSC cells, providing a molecular reading key for this complex pathology.</p

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead