100 research outputs found

    Introduction to Psychology

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    Introduction to Psychology is a modified version of Psychology 2e - OpenStax

    Modern Developments in Transcranial Magnetic Stimulation (TMS) – Applications and Perspectives in Clinical Neuroscience

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    Transcranial magnetic stimulation (TMS) is being increasingly used in neuroscience and clinics. Modern advances include but are not limited to the combination of TMS with precise neuronavigation as well as the integration of TMS into a multimodal environment, e.g., by guiding the TMS application using complementary techniques such as functional magnetic resonance imaging (fMRI), electroencephalography (EEG), diffusion tensor imaging (DTI), or magnetoencephalography (MEG). Furthermore, the impact of stimulation can be identified and characterized by such multimodal approaches, helping to shed light on the basic neurophysiology and TMS effects in the human brain. Against this background, the aim of this Special Issue was to explore advancements in the field of TMS considering both investigations in healthy subjects as well as patients

    Learning Disabilities

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    Learning disabilities are a heterogeneous group of disorders characterized by failure to acquire, retrieve, or use information competently. They are the most severe and chronic form of learning difficulty in children. They can be present at birth or acquired as a result of illness, exposure to toxins, poor nutrition, medical treatment, sociocultural deprivation, or injury. Learning problems typically consist in failure to acquire reading, writing, or math skills, which are traditionally considered core domains. This book explores the epidemiology, neurobiological bases, and diagnostic tools necessary for a comprehensive assessment of children with learning disabilities. It also presents examples of children with specific learning disabilities and explains possible intervention strategies

    Physical and Mental Coordination in the Elderly: A Causal Role for the Cerebellum?

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    The mechanisms underlying the progressive changes in tissues and organs that characterise normal ageing remain unclear. The cerebellum is known to play a major role in motor function, but recent research suggests it plays an equivalent role in cognition. Working with the hypothesis that cortico-cerebellar loops ensure smooth and coordinated activity in both domains, this thesis investigates the possible role of the cerebellum in normal ageing and in interventions to improve function, seeking to contribute to both theoretical and applied approaches to ageing. Study one investigated relationships between motor and cognitive function using raw data from a national normative sample of adults aged 16 to 75, employing a test battery assessing motor and cognitive skills. Differences between age groups were demonstrated in some tests of complex processing speed, working memory and executive function, with suggestive evidence that senescence in tests is reflected in tests sensitive to cerebellar function. Study two refined the battery, while including further measures of motor and memory performance to investigate linkages between cognitive and cerebellar function. Using a sample of 256 older adults, results were variable but provided evidence that pegboard performance could act as a predictor of some cognitive functions. Study three investigated a proactive intervention for healthy older adults designed to improve cerebellar function, and therefore balance and executive function. This involved an 8-10 week self-administered, internet-based coordinative exercise intervention using a ‘cerebellar challenge’ suite of graded activities. Performance on a basket of tests was assessed before and after, and also compared with performance changes in a no-intervention control group. Significantly greater benefits for the intervention group than the controls were found for balance physical coordination and controlled information processing. Overall, these studies support current research indicating cerebellar contribution to both cognitive and motor problems arising in old age, and present evidence that non-verbal memory and controlled speeded information problems may be alleviated through targeted activities affecting cerebellar function improving postural stability and physical coordination

    Advances in the neurocognition of music and language

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    Watershed-based Segmentation of the Midsagittal Section of the Corpus Callosum in Diffusion MRI

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    Abstract -The corpus callosum (CC) is one of the most important white matter structures of the brain, interconnecting the two cerebral hemispheres. The CC is related to several diseases including dyslexia, autism, multiple sclerosis and lupus, which make its study even more important. We propose here a new approach for fully automatic segmentation of the midsagittal section of CC in magnetic resonance diffusion tensor images, including the automatic determination of the midsagittal slice of the brain . It uses the watershed transform and is performed on the fractional anisotropy map weighted by the projection of the principal eigenvector in the left-right direction. Experiments with real diffusion MRI data showed that the proposed method is able to quickly segment the CC and to the determinate the midsagittal slice without any user intervention. Since it is simple, fast a nd does not require parameter settings, the proposed method is well suited for clinical applications

    The brain structure during language development: neural correlates of sentence comprehension in preschool children

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    Language skills increase as the brain matures and language specialization is linked to the left hemisphere. Among distinct language domains, sentence comprehension is particularly vital in language acquisition and, by comparison, requires a much longer time-span before full mastery in children. Although accumulating studies have revealed the neural mechanism underlying sentence comprehension acquisition, the development of the brain’s gray matter and its relation to sentence comprehension had not been fully understood. This thesis employs structural magnetic resonance imaging and diffusion-weighted imaging data to investigate the neural correlates of sentence comprehension in preschoolers both cross-sectionally and longitudinally. The first study examines how cortical thick- ness covariance is relevant for syntax in preschoolers and changes across development. Results suggest that the cortical thickness covariance of brain regions relevant for syntax increases from preschoolers to adults, whilst preschoolers with superior language abilities show a more adult-like covariance pattern. Reconstructing the white matter fiber tract connecting the left inferior frontal and superior temporal cortices using diffusion-weighted imaging data, the second study suggests that the reduced cortical thickness covariance in the left frontotemporal regions is likely due to immature white matter connectivity during preschool. The third study then investigated the cortical thickness asymmetry and its relation to sentence comprehension abilities. Results show that longitudinal cortical thick- ness asymmetry in the inferior frontal cortex was associated with improvements in sentence comprehension, further suggesting the crucial role of the inferior frontal cortex for sentence comprehension acquisition. Taken together, evidence from gray and white matter data provides new insights into the neuroscientific model of language acquisition and the emergence of syntactic processing during language development

    Examining Brain Connectivity and Reading Ability in Children

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    In this thesis, I investigated the relationship between functional and structural connectivity and reading ability in children. Prior research has tended to use single word reading measures or composite measures, however this is problematic as reading is a complex skill relying on multiple subskills, such as decoding efficiency, sight word reading efficiency, reading comprehension, and rapid automatized naming. As a result, the multi-faceted relationship between brain connectivity and reading ability is not well understood. I aimed to address this issue by considering multiple reading subskills while examining the neural substrates of reading. In Chapter 2, I examined how individual differences in decoding efficiency, sight word reading efficiency, reading comprehension, and rapid automatized naming relate to resting-state functional connectivity from regions of the brain’s reading network. I found that distinct functional networks in both hemispheres of the brain support different components of reading in children. In Chapter 3, I built on these findings to examine how individual differences in the same reading subskills are associated with structural connectivity in reading-related white matter tracts, as measured by diffusion tensor imaging. Similar to Chapter 2, the results of Chapter 3 suggested that different components of reading ability are supported by structural characteristics in distinct bilateral tracts of the brain. Importantly, many of the effects observed in Chapters 2 and 3 were found to be specific to reading subskills and were not associated with more general cognitive abilities. In Chapter 4, I examined how improvements in reading ability are related to changes in structural and functional connectivity, by measuring brain connectivity pre- and post-intervention in a group of children with reading disability. I also investigated whether individual differences in the amount of improvement in reading ability post-intervention was predicted by pre-intervention brain connectivity. I found that gains in reading ability were associated with changes in resting-state functional connectivity, particularly between reading-related regions and frontal regions as well as regions of the default mode network. Changes in white matter microstructure of the right arcuate fasciculus were strongly associated with gains in single word reading abilities. Additionally, results showed that distinct pre-intervention characteristics of resting-state functional connectivity and white matter integrity predicted the magnitude of subsequent gains in reading ability following the reading intervention. Chapter 5 summarizes the findings of this thesis in relation to the current literature and presents recommendations for future research on reading ability and brain connectivity

    Réorganisation cérébrale chez l’adulte sourd : de la privation à la restauration auditive

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    On estime que 5 % de la population dans le monde souffre d’une perte auditive handicapante, dont 34 millions d’enfants. Ce déficit perceptif, lorsqu’il survient dès la naissance ou lors des premières années de vie, a de multiples répercussions sur le développement cérébral et neurocognitif. La réorganisation cérébrale ayant cours dans le cerveau des individus privés de l’audition précocement constitue un sujet d’étude très prisé par la communauté scientifique, mais pour laquelle de nombreuses questions restent en suspens. Ainsi, les articles qui composent cette thèse ont pour objectif principal d’améliorer nos connaissances portant sur les mécanismes de réorganisation cérébrale, tant au niveau fonctionnel que structurel afin de mieux comprendre leur implication comportementale chez les individus sourds. Pour ce faire, nous avons souhaité investiguer, par le biais de l’imagerie par résonance magnétique fonctionnelle, quel était le lien entre les activations cérébrales et les performances comportementales lors d’une tâche portant sur les mouvements biologiques chez des adultes sourds congénitaux, en comparaison à des pairs neurotypiques. L’article 1 révèle que les individus sourds présentent une sensibilité accrue à la reconnaissance du mouvement biologique, et notamment des emblèmes, en comparaison à des individus neurotypique. De plus, cette spécificité comportementale observée uniquement chez les individus sourds, s’accompagne d’un recrutement extensif des régions comprises dans le gyrus temporal supérieur, et tout particulièrement le cortex auditif primaire ainsi que le planum temporale. Nos résultats supportent la présence d’une réorganisation intermodale qui s’exprime par le recrutement cérébral des régions auditives lors de stimulations visuelles complexes, entraînant une amélioration de la reconnaissance des mouvements biologiques chez les adultes sourds. Par la suite, nous avons souhaité préciser les mécanismes de réorganisation cérébrale de type structurel. En raison de l’hétérogénéité des résultats rapportés précédemment dans la littérature à propos des changements de matière grise et de matière blanche chez les enfants, les adolescents et les adultes sourds privés de l’audition précocement, la réalisation d’une revue systématique a permis de répertorier l’ensemble des changements structurels obtenus par le biais de diverses techniques d’analyse en imagerie par résonance magnétique. L’article 2 de la présente thèse offre une généralisation des altérations structurelles et intègre une visée clinique à la compréhension de ces changements anatomiques et notamment leur impact sur le développement langagier et neurocognitif. Mis ensemble, ces résultats contribuent à une meilleure appréciation des changements cérébraux à la suite d’une privation précoce de l’audition. En outre, ils offrent une perspective développementale à ces changements par la description de comportements adaptatifs à la situation de handicap auditif, ainsi que du profil neurocognitif de ces individus, dans le but d’apporter de nouvelles pistes aux stratégies de restauration de l’audition et du langage.It is estimated that 5% of the world’s population suffers from a disabling hearing loss, including 34 million children. This sensory deficit, when it occurs at birth or in the first years of life, has multiple repercussions on the brain and neurocognitive development. The brain reorganization taking place in the brain of early-deaf individuals is an area of research highly valued by the scientific community but for which many questions remain unanswered. Thus, the main objective of the articles in this thesis is to improve our knowledge of brain reorganization mechanisms, both at the functional and structural levels, in deaf individuals. This will allow a better understanding of their impact on the behavioural adaptations of deaf individuals. To do this, we investigated, through functional magnetic resonance imaging, the relationship between brain activation and behavioural performance in a task involving biological motions in early-deaf adults, compared to hearing peers. Article 1 reveals that deaf individuals are more sensitive to the recognition of biological motion, including emblems, than hearing individuals. In addition, this behavioural specificity, observed only in deaf individuals, is accompanied by extensive recruitment of the regions included in the superior temporal gyrus, such as the primary auditory cortex but more particularly, the planum temporale. Our results support the presence of intermodal reorganization, which is expressed by brain recruitment of auditory regions during complex visual stimuli, leading to improved recognition of the biological motion in early deaf adults. On the other hand, we wanted to specify the mechanisms of structural brain reorganization. Due to the heterogeneity of the results previously reported in the literature on changes in grey matter and white matter in early-deaf children, adolescents, and adults, the completion of a systematic review identified all the structural changes obtained through various magnetic resonance imaging analysis techniques. The second article of this thesis offers a generalization of structural alterations. It also integrates a clinical frame to the understanding of these anatomical changes to optimize the language and neurocognitive development of these individuals. Together, these results contribute to a better appreciation of brain changes following an early hearing loss at both the functional and structural levels. Besides, they offer a developmental perspective to these changes by describing adaptive behaviours and the neurocognitive profile of these individuals, with providing new insights into hearing and language restoration strategies
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