190 research outputs found
Event-related potential alterations in fragile X syndrome
Fragile X Syndrome (FXS) is the most common form of X-linked intellectual disability (ID), associated with a wide range of cognitive and behavioral impairments. FXS is caused by a trinucleotide repeat expansion in the FMR1 gene located on the X-chromosome. FMR1 is expected to prevent the expression of the âfragile X mental retardation protein (FMRP)â, which results in altered structural and functional development of the synapse, including a loss of synaptic plasticity. This review aims to unveil the contribution of electrophysiological signal studies for the understanding of the information processing impairments in FXS patients. We discuss relevant event-related potential (ERP) studies conducted with full mutation FXS patients and clinical populations sharing symptoms with FXS in a developmental perspective. Specific deviances found in FXS ERP profiles are described. Alterations are reported in N1, P2, Mismatch Negativity (MMN), N2, and P3 components in FXS compared to healthy controls. Particularly, deviances in N1 and P2 amplitude seem to be specific to FXS. The presented results suggest a cascade of impaired information processes that are in line with symptoms and anatomical findings in FXS
Conservation génétique du chevalier cuivré (Moxostoma hubbsi) : effet tampon du temps de génération sur l'érosion de la diversité génétique
La constante hausse dâactivitĂ©s humaines, provoquant la destruction des habitats naturels, a menĂ© Ă lâextinction de plusieurs espĂšces. La diversitĂ© gĂ©nĂ©tique jouant un rĂŽle primordial dans le potentiel Ă©volutif dâune espĂšce, la conservation gĂ©nĂ©tique fournit de plus en plus dâoutils pour prĂ©server la biodiversitĂ©. Le Chevalier cuivrĂ© (Moxostoma hubbsi), espĂšce menacĂ©e exclusive au QuĂ©bec, a une distribution extrĂȘmement restreinte, limitĂ©e Ă la RiviĂšre Richelieu et Ă une courte section du fleuve Saint-Laurent. Etonnamment, cette population unique et vieillissante possĂšde un niveau de diversitĂ© gĂ©nĂ©tique trĂšs Ă©levĂ© sans signe apparent de consanguinitĂ©, alors que son histoire dĂ©mographique rĂ©cente ainsi que les divers estimĂ©s de taille effective suggĂšrent un dĂ©clin graduel Ă©chelonnĂ© sur une longue pĂ©riode temporelle. Les rĂ©sultats de ce mĂ©moire mettent en Ă©vidence le potentiel des donnĂ©es gĂ©nĂ©tiques dans un plan de rĂ©tablissement et identifient certains facteurs pouvant influencer lâimpact gĂ©nĂ©tique dâune rĂ©duction de taille chez les espĂšces Ă long temps de gĂ©nĂ©ration.Increasing human activities have caused destruction and fragmentation of natural habitats, leading to the extinction of many species. Since genetic diversity plays an important role in the evolutionary potential of a species, conservation genetics is increasingly providing adequate tools needed towards the preservation of biodiversity. The Copper redhorse (Moxostoma hubbsi), an endangered species of QuĂ©bec, has an extremely restricted distribution, limited to the Richelieu River and a short section of the St.Lawrence River. Surprisingly, this unique and ageing remaining population exhibits a high level of genetic diversity without sign of inbreeding, where recent demographic history and effective population size estimates suggest a gradual demographic decline scaled on a large time period. Our results clearly demonstrate the potential of genetic data towards effective conservation, as well suggesting that long generation times may act as a buffering effect contributing to reduce the pace of genetic diversity erosion in threatened species
Histoire critique de la transition entre paléolithiques moyen et supérieur en archéologie préhistorique française, des origines à la seconde moitié du XXe siÚcle
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal
Nature, culture et progrÚs : histoire comparative du concept de transition entre paléolithiques moyen et supérieur en archéologie préhistorique
Doctorat effectuĂ© en cotutelle Pour le dĂ©partement d'histoire de l'UniversitĂ© de MontrĂ©al, M.M. Jacques G. Ruelland et Othmar Keel, Pour le laboratoire P.A.C.E.A.â U.M.R. 5199. C.N.R.S., de l'Ăcole doctorale des sciences Terre-Mer, directeurs successifs, M. P.-Y. Demars, puis M. Michel Lenoir. ThĂšse soutenue Ă Bordeaux le 6 juin 2012.Cette thĂšse a pour objectif dâĂ©tudier sur le plan historique une controverse
scientifique persistante en préhistoire : le problÚme de la transition entre Paléolithiques
moyen et supĂ©rieur, en tentant dâen expliquer la durĂ©e en termes de construction et de
transformation des modĂšles antagoniques, ainsi que le rĂŽle de cette controverse dans
lâacquisition de connaissances, afin dâĂ©lucider comment sâest produit le dĂ©placement des
enjeux que prĂ©sente son Ă©tat actuel. Il sâagit de dresser un historique de la controverse
entourant la transition entre Paléolithiques moyen et supérieur afin de circonscrire sur le
plan chronologique les persistances et lâĂ©volution des positions antagonistes dans leurs
composantes Ă©pistĂ©mologiques. Pour clarifier cette dĂ©marche, il faut dâabord caractĂ©riser ce
qui constitue cette controverse particuliĂšre pour les prĂ©historiens Ă lâaide de lâapport de
lâhistoire des sciences, et quelle mĂ©thode dâanalyse sera utilisĂ©e dans le prĂ©sent travail. Il
sera ainsi possible de relier ces éléments au problÚme scientifique choisi comme sujet
dâĂ©tude, prĂ©sentĂ© dans ses caractĂšres gĂ©nĂ©raux et spĂ©cifiques, pour modĂ©liser la dĂ©finition
structurale des modÚles explicatifs protagonistes au débat sur la transition entre
Paléolithiques moyen et supérieur.
La méthodologie proposée sera ensuite appliquée à la controverse, pour découper
son déroulement chronologique en trois phases historiques distinctes par leur axe de
recherche spécifique, chacune des phases étant décrite sur trois niveaux structuraux
(donnĂ©es et mĂ©thodologie, paradigmes opĂ©ratoires, paradigme mĂ©taphysique), afin dâisoler
les constantes et les inflexions, et dâĂ©tablir un modĂšle explicatif de sa dynamique historique
jusquâĂ son Ă©tat actuel. Lâambition de cette thĂšse est de sâappuyer sur lâhistoire des sciences
pour clarifier sur le plan théorique pour les préhistoriens la dynamique historique de cette
controverse centrale Ă lâĂ©tude du changement culturel en prĂ©histoire, et des modĂšles qui sây
confrontent toujours, et tenter, Ă partir de lâĂ©tude de ce problĂšme dâarchĂ©ologie
prĂ©historique, dâĂ©baucher en retour un modĂšle historique et structural dâĂ©tude de cas dâune
controverse spécifique et de son apport au niveau du changement conceptuel en science qui
pourrait ĂȘtre utile Ă lâhistoire des sciences.This thesisâ main object is to study on an historical level a long-lasting scientific
controversy in Prehistoric archaeology, the Middle to Upper Palaeolithic transition, by
attempting to explain the persistence of that debate in terms of construction and
transformation of antagonistic models of explanation, and by showing how that controversy
had play a role on the acquisition of knowledge, to elucidate how the debate itself had
change since its origin. On a chronological scale, the evolution of some epistemological
elements inside the confrontation of opposed hypothesis could be contrasted with
conservative notions. To make that process clear, it is necessary to characterize what
constitute that specific controversy for prehistorians with the tool given by the history of
sciences, and what kind of analytical methodology can be call upon for doing so. Then, it
will be possible to link those elements with the scientific problem itself to establish a
structural model of this debateâs theoretical positions of the protagonists. This methodology
could then be use to separate the history of that debate in three sections, each with its
specific research axis, each phase in three structural level (data and methods, paradigms,
meta-paradigm) to create a general model of the evolution of that controversy. The ambition
of that thesis is to use history of scienceâs contribution as a way to clarify on a theoretical
level the goals of that debate, and its implication on the study of cultural change for
prehistorical archaeologists community, and to initiate for scienceâs historians a historical
and structural model of scientific controversies, and their weight on conceptual change base
on a specific case study
Développement cérébral normal et convulsions fébriles : étude d'électrophysiologie visuelle
ThÚse numérisée par la Direction des bibliothÚques de l'Université de Montréal
Differential Maturation of Brain Signal Complexity in the Human Auditory and Visual System
Brain development carries with it a large number of structural changes at the local level which impact on the functional interactions of distributed neuronal networks for perceptual processing. Such changes enhance information processing capacity, which can be indexed by estimation of neural signal complexity. Here, we show that during development, EEG signal complexity increases from one month to 5 years of age in response to auditory and visual stimulation. However, the rates of change in complexity were not equivalent for the two responses. Infantsâ signal complexity for the visual condition was greater than auditory signal complexity, whereas adults showed the same level of complexity to both types of stimuli. The differential rates of complexity change may reflect a combination of innate and experiential factors on the structure and function of the two sensory systems
The quantitative genetics of incipient speciation: Heritability and genetic correlations of skeletal traits in populations of diverging favia fragum ecomorphs
Recent speciation events provide potential opportunities to understand the microevolution of reproductive isolation. We used a marker-based approach and a common garden to estimate the additive genetic variation in skeletal traits in a system of two ecomorphs within the coral species Favia fragum: a Tall ecomorph that is a seagrass specialist, and a Short ecomorph that is most abundant on coral reefs. Considering both ecomorphs, we found significant narrow-sense heritability (h 2) in a suite of measurements that define corallite architecture, and could partition additive and nonadditive variation for some traits. We found positive genetic correlations for homologous height and length measurements among different types of vertical plates (costosepta) within corallites, but negative correlations between height and length within, as well as between costosepta. Within ecomorphs, h 2 estimates were generally lower, compared to the combined ecomorph analysis. Marker-based estimates of h 2 were comparable to broad-sense heritability (H) obtained from parent-offspring regressions in a common garden for most traits, and similar genetic co-variance matrices for common garden and wild populations may indicate relatively small G à E interactions. The patterns of additive genetic variation in this system invite hypotheses of divergent selection or genetic drift as potential evolutionary drivers of reproductive isolation. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution
Could we use parent report as a valid proxy of child report on anxiety, depression, and distress? : a systematic investigation of fatherâmotherâchild triads in children successfully treated for leukemia
Background
Systematic assessment of emotional distress is recommended in after care. Yet, it is unclear if parent report may be used as a proxy of child report. The aim of this study was to assess agreements and differences and explore possible moderators of disagreement between child and parent ratings.
Methods
Sixtyâtwo young survivors treated for acute lymphoblastic leukemia (9â18 years) and both parents responded to the Beck Youth Inventory (anxiety and depression) and the distress rating scale on the child's status. Parents completed the Brief Symptom Inventoryâ18 on their own psychological status. Systematic analyses of agreement and differences were performed.
Results
Motherâchild and fatherâchild agreements were fair on anxiety, depression, and distress (median intraclass correlation coefficient = 0.37). Differences between parents and children were medium sized (median d = 0.55) with parents giving higher scores than their children on anxiety, depression, and distress. Mothers reported distress more frequently than fathers (39 vs. 17%) when children reported none. The child being female and lower parental income were associated with lower agreement in fathers when rating child distress. Higher levels of parental psychological symptoms were consistently associated with lower agreement.
Conclusions
Parentâchild differences when rating adolescent survivorsâ difficulties may be more important than previously thought. Parent report probably cannot be considered as a valid proxy of older child report on such internalized domains as anxiety, depression, or distress in the afterâcare clinic. Parentsâ report is also likely to be influenced by their own mood, a factor that should be corrected for when using their report
Prolonged and unprolonged complex febrile seizures differently affect frontal theta brain activity
Objective: Studies have identified persistent cognitive and functional deficits, which could be
linked to each other, in children with complex febrile seizures (FS). Our aim was to investigate
differences in brain activity in children with a history of complex FS, through a study paradigm
associated with the development of learning capacities and using electroencephalographic
(EEG) signal. To further increase our understanding of these differences, complex FS were
studied separately depending on their type.
Method: EEG was recorded in 43 children with past FS. Brain activity associated with auditory
learning was investigated using a habituation paradigm, in which repetition suppression (RS) is
typically found following stimulus repetition. Auditory stimuli were repeated three times, and
each presentation were analysed separately in the time-frequency (TF) domain. A mixedanalysis of variance was used to assess differences in spectral power between stimulus repetition
and FS type (simple vs complex prolonged; CP vs complex unprolonged; CUP).
Results: Repetition effects were found in the 3-6 Hz during 150-600ms time window after
stimulus onset at frontal sites (F(2, 40)=5.645, p=0.007, η2p=0.220). Moreover, an interaction
effect between stimulus repetition and FS type (F(4, 80)=2.607, p=0.042, η2p=0.115) was
found. Children with CP FS showed greater increase in spectral power in response to the first
stimulus presentation, while children with CUP FS failed to show a RS pattern.
Significance: Our results show distinct abnormalities in brain activity to a habituation paradigm.
We argue that these changes suggest children with CP FS may be hyperexcitable, while children
with CUP FS show impaired habituation processes. Still, these differences may be associated
with other clinical features linked to complex FS as well. Hence, the role of these differences in
complex FS incidence and prognosis should be the subject of future studies
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