Anticipatory postural adjustments in a bimanual load-lifting task in children with developmental coordination disorder

International audienceAIM Postural control is a fundamental component of action in which deficits have been shown to contribute to motor difficulties in children with developmental coordination disorder (DCD). The purpose of this study was to examine anticipatory postural adjustments (APAs) in children with DCD in a bimanual load-lifting task. METHOD Sixteen children with reported motor problems (two females, 14 males; mean age 9y; SD 2y) and 16 typically developing, age-matched children (six females, 10 males; mean age 9y; SD 2y) took part in the study. The task required the children to maintain a stable elbow angle, despite imposed or voluntary unloading of the forearm. APAs were assessed using electromyography and kinematics analysis. RESULTS Although children with DCD could compensate for the consequences of unloading, the results demonstrated that APAs were less efficient in children with DCD than in typically developing children. A positive and significant coefficient of regression between the flexor inhibition latency and the postural stabilization was only found in typically developing children. INTERPRETATION The impaired fine-tuning of the muscle contribution and the poor stabilization performances demonstrate poor predictive modelling in DCD

Recruitment of Both the Mirror and the Mentalizing Networks When Observing Social Interactions Depicted by Point-Lights: A Neuroimaging Study

Background: Understanding social interactions requires the ability to accurately interpret conspecifics ’ actions, sometimes only on the basis of subtle body language analysis. Here we address an important issue that has not yet received much attention in social neuroscience, that of an interaction between two agents. We attempted to isolate brain responses to two individuals interacting compared to two individuals acting independently. Methodology/Principal Findings: We used minimalistic point-light displays to depict the characters, as they provide the most straightforward way to isolate mechanisms used to extract information from motion per se without any interference with other visual information. Functional magnetic resonance imaging (fMRI) method was used to determine which brain regions were recruited during the observation of two interacting agents, mimicking everyday social scenes. While the mirror and mentalizing networks are rarely concurrently active, we found that both of them might be needed to catch the social intentions carried by whole-body motion. Conclusions/Significance: These findings shed light on how motor cognition contributes to social cognition when social information is embedded in whole-body motion only. Finally, the approach described here provides a valuable and origina

Comprendre une interaction sociale par le corps en action : contribution de mécanisme miroir et implication dans l'autisme

Body language plays a major role in social communication. The overall aim of this thesis is to enlighten the contribution of the body in action in social interaction (SI) understanding. A developmental approach reveals the mechanisms responsible for the set-up of social abilities in children, who by nature are extensively social. In autism, a complex developmental disorder, on the contrary the social dimension is deeply affected. Our studies tackle the use of information carried by the body in action, in a social context in this pathology. The originality of our experimental paradigm relies on the use of human motion (HM), or point-light animations, that enable to isolate the social information carried by the body in action only. Subjects watched two actors engaged or not in a social interaction. A two-fold approach, behavioral and using fMRI, reveals the use and the set-up of motor simulation and questions its implication in autism. Children from 4- to 6-years of age and children with autism make use of visual information extracted from HM to understand SI, even though their performance does not reach those of adults. In adults, beyond the mentalizing network, we enlighten the importance of the mirror-neuron system for social cognition. In children, fMRI revealed the early functional recruitment of the inferior frontal gyrus, which is part of the mirror-neuron system, during the observation of social scenes. The general discussion establishes a tight link between the set-up of the mirroring system and the building of action representations. We also question the integrity of this process in autism. In conclusion, these studies bring to light the fundamental role of the mirroring mechanism in the social development of a child.Le langage du corps tient une place prépondérante dans la communication sociale et ceci dès la petite enfance. L'objectif de ce travail de thèse est de déterminer la contribution du corps en action dans la compréhension des interactions sociales (IS). L'approche développementale nous renseigne sur les mécanismes présidant à sa mise en place chez l'enfant, être éminemment social. En revanche dans l'autisme, trouble neurodéveloppemental complexe, la dimension sociale est altérée. Nos études questionnent dans cette pathologie l'utilisation de l'information portée par le corps en mouvement, dans un contexte social. L'originalité de notre paradigme expérimental repose sur l'utilisation de mouvements humains (MH), ou animations en points lumineux, qui permettent d'isoler l'information sociale portée par le corps en action. Nous avons présenté à nos sujets des scènes visuelles présentant deux acteurs engagés dans une interaction sociale ou pas. Une double approche, comportementale et en IRMf, nous éclaire sur l'utilisation et la mise en place de la simulation motrice et nous permet de questionner son implication dans l'autisme. Nous montrons que les enfants entre 4 et 6 ans et les enfants autistes utilisent les informations visuelles portées par le MH pour comprendre une IS, bien que leurs performances ne soient pas encore optimales. Chez l'adulte, en plus du réseau de la mentalisation attendu, nous avons mis en évidence l'importance du réseau des mécanismes miroirs dans la cognition sociale. Chez l'enfant, l'IRMf nous a permis de rapporter pour la première fois un recrutement fonctionnel précoce du gyrus frontal inférieur, siège du système des neurones miroirs, lors de l'observation des scènes sociales. La discussion générale établit un lien étroit entre la mise en place du mécanisme miroir et la construction des représentations de l'action, elle interroge aussi l'intégrité de ce processus dans l'autisme. En conclusion, ces études ouvrent la voie au rôle fondateur du mécanisme miroir dans le développement social de l'enfant

Hand preferences in preschool children: Reaching, pointing and symbolic gestures

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From Action to Interaction: Exploring the Contribution of Body Motion Cues to Social Understanding in Typical Development and in Autism Spectrum Disorders

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Hand preferences in preschool children: Reaching, pointing and symbolic gestures

International audienceManual asymmetries emerge very early in development and several researchers have reported a significant right-hand bias in toddlers although this bias fluctuates depending on the nature of the activity being performed. However, little is known about the further development of asymmetries in preschoolers. In this study, patterns of hand preference were assessed in 50 children aged 3–5 years for different activities, including reaching movements, pointing gestures and symbolic gestures. Contrary to what has been reported in children before 3 years of age, we did not observe any difference in the mean handedness indices obtained in each task. Moreover, the asymmetry of reaching was found to correlate with that of pointing gestures, but not with that of symbolic gestures. In relation to the results reported in infants and adults, this study may help deciphering the mechanisms controlling the development of handedness by providing measures of manual asymmetries in an age range that has been so far rather neglected

Anticipatory postural adjustments in a bimanual load-lifting task in children with developmental coordination disorder

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Deciphering human motion to discriminate social interactions: a developmental neuroimaging study

International audienceNon-verbal communication plays a major role in social interaction understanding. Using functional magnetic resonance imaging, we explored the development of the neural networks involved in social interaction recognition based on human motion in children (8-11), adolescents (13-17), and adults (20-41). Participants watched point-light videos depicting two actors interacting or moving independently and were asked whether these agents were interacting or not. All groups successfully performed the discrimination task, but children had a lower performance and longer response times than the older groups. In all three groups, the posterior parts of the superior temporal sulci and middle temporal gyri, the inferior frontal gyri and the anterior temporal lobes showed greater activation when observing social interactions. In addition, adolescents and adults recruited the caudate nucleus and some frontal regions that are part of the mirror system. Adults showed greater activations in parietal and frontal regions (part of them belonging to the social brain) than adolescents. An increased number of regions that are part of the mirror system network or the social brain, as well as the caudate nucleus, were recruited with age. In conclusion, a shared set of brain regions enabling the discrimination of social interactions from neutral movements through human motion is already present in 8-year-old children. Developmental processes such as refinements in the social brain and mirror system would help grasping subtle cues in non-verbal aspects of social interactions