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This current article presents the main work of the experts gathered by INSERM within the framework of the collective expertise procedure attached to the Institute of Public Health to respond to the request of the Caisse nationale de solidarité pour l’autonomie (French National Solidarity Fund for Autonomy) concerning the support and care of people with a developmental coordination disorder (DCD) or dyspraxia. This report (synthesis, analyses and recommendations) was published in December 2019. The work of the experts has made it possible to review the scientific knowledges on developmental coordination disorder at both national and international levels based on the available scientific literature. In this synthesis, we will attempt to present the essential points of the analyses and recommendations resulting from the work of the experts group concerning terminology, typology, epidemiology, brain imaging, genetics, sensory-motor and cognitive deficits, writing disorders, impact on activities of daily living, identification and diagnosis. International studies on DCD show recurrent methodological bias and DCD is a generic term poorly defined by the DSM-5, for which the diagnosis includes a necessary but insufficient standardized assessment of motor coordination. Developmental tests assessing the maturation of neuromotor development underlying motor function should complement the assertion of the diagnosis, as well as other multidimensional investigations of cognitive, sensorial and motor function in order to make a differential diagnosis and report a typology. In addition, the individual impact of the disability on activities, participation and quality of life must be evaluated, not only in childhood but also as adults., L’objectif de cet article est de faire connaître les principaux travaux des experts réunis par l’INSERM dans le cadre de la procédure d’expertise collective rattaché à l’Institut de santé publique pour répondre à la demande de la Caisse nationale de solidarité pour l’autonomie concernant l’accompagnement et la prise en charge des personnes présentant un trouble développemental de la coordination (TDC) ou dyspraxie. Le rapport (synthèse, analyses et recommandations) a été publié en décembre 2019. Les travaux des experts ont permis de faire un état des connaissances scientifiques sur le trouble développemental de la coordination à un niveau tant national qu’international, basé sur la littérature scientifique disponible. Nous tenterons à travers cette article de synthèse de présenter les points essentiels des analyses et recommandations issues des travaux du groupe d’experts concernant la terminologie, la typologie, l’épidémiologie, l’imagerie cérébrale, la génétique, les fonctions déficitaires sensorimotrices et cognitives, le trouble de l’écriture, l’impact sur les activités de la vie quotidiennes, le repérage et le diagnostic. Les études au niveau international sur le TDC font apparaître des biais méthodologiques récurrents et le TDC est un terme générique mal défini par le DSM-5, pour lequel le diagnostic comporte une évaluation de la coordination motrice standardisée et normée, nécessaire mais pas suffisante. Des tests développementaux évaluant la maturation du développement neuromoteur sous-jacent à la fonction motrice doivent compléter l’affirmation du diagnostic, ainsi que d’autres investigations multidimensionnelles des fonctions cognitives, sensorielles et motrices afin de réaliser un diagnostic différentiel et de rendre compte d’une typologie. De plus, l’impact individuel du handicap sur les activités, la participation et la qualité de vie, doit être évalué, non seulement dans l’enfance mais aussi à l’âge adulte.

Introduction NF1 children have cognitive disorders, especially in executive functions, visuospatial, and language domains, the pathophysiological mechanisms of which are still poorly understood. Materials and methods A correlation study was performed from neuropsychological assessments and brain MRIs of 38 NF1 patients and 42 controls, all right-handed, aged 8–12 years and matched in age and gender. The most discriminating neuropsychological tests were selected to assess their visuospatial, metaphonological and visuospatial working memory abilities. The MRI analyses focused on the presence and location of Unidentified Bright Objects (UBOs) (1), volume analysis (2) and diffusion analysis (fractional anisotropy and mean diffusivity) (3) of the regions of interest including subcortical structures and posterior fossa, as well as shape analysis of subcortical structures (4). The level of attention, intelligence quotient, age and gender of the patients were taken into account in the statistical analysis. Then, we studied how diffusion and volumes parameters were associated with neuropsychological characteristics in NF1 children. Results NF1 children present different brain imaging characteristics compared to the control such as (1) UBOs in 68%, (2) enlarged total intracranial volume, involving all subcortical structures, especially thalamus, (3) increased MD and decreased FA in thalamus, corpus callosum and hippocampus. These alterations are diffuse, without shape involvement. In NF1 group, brain microstructure is all the more altered that volumes are enlarged. However, we fail to find a link between these brain characteristics and neurocognitive scores. Conclusion While NF1 patients have obvious pathological brain characteristics, the neuronal substrates of their cognitive deficits are still not fully understood, perhaps due to complex and multiple pathophysiological mechanisms underlying this disorder, as suggested by the heterogeneity observed in our study. However, our results are compatible with an interpretation of NF1 as a diffuse white matter disease.

In a bimanual task, proprioception provides information about position and movement of upper arms. Developmental studies showed improvement of proprioceptive accuracy and timing adjustments of muscular events from childhood to adulthood in bimanual tasks. However, the cortical maturational changes related to bimanual coordination is not fully understood. The aim of this study was to investigate cortical correlates underlying motor planning and upper limb stabilization performance at left (C3) and right (C4) sensorimotor cortices using event-related potential (ERP) analyses. We recruited 46 participants divided into four groups (12 children: 8–10 years, 13 early adolescents: 11–13 years, 11 late adolescents: 14–16 years and 10 young adults: 20–35 years). Participants performed a bimanual load-lifting task, where the left postural arm supported the load and the right motor arm lifted the load. Maximal amplitude of elbow rotation (MA%) of the postural arm, reaction time (RT) and EMG activity of biceps brachii bilaterally were computed. Laplacian-transformed ERPs of the electroencephalographic (EEG) signal response-locked to motor arm biceps EMG activity onset were analyzed over C3 and C4. We found a developmental effect for behavioral and EEG data denoted by significant decrease of MA% and RT with age, earlier inhibition of the biceps brachii of the postural arm in adults and earlier EEG activation/inhibition onset at C3/C4. Amplitude of the negative wave at C4 was higher in children and early adolescents compared to the other groups. In conclusion, we found a maturational process in cortical correlates related to motor planning and upper limb stabilization performance with interhemispheric lateralization appearing during adolescence. Findings may serve documenting bimanual performance in children with neurodevelopmental disorders.

Developmental dyslexia (DD) and developmental coordination disorder (DCD) are distinct diagnostic disorders. However, they also frequently co-occur and may share a common etiology. It was proposed conceptually a neural network framework that explains differences and commonalities between DD and DCD through impairments of distinct or intertwined cortico-subcortical connectivity pathways. The present study addressed this issue by exploring intrinsic cortico-striatal and cortico-cerebellar functional connectivity in a large (n = 136) resting-state fMRI cohort study of 8–12-year-old children with typical development and with DD and/or DCD. We delineated a set of cortico-subcortical functional circuits believed to be associated with the brain’s main functions (visual, somatomotor, dorsal attention, ventral attention, limbic, frontoparietal control, and default-mode). Next, we assessed, using general linear and multiple kernel models, whether and which circuits distinguished between the groups. Findings revealed that somatomotor cortico-cerebellar and frontoparietal cortico-striatal circuits are affected in the presence of DCD, including abnormalities in cortico-cerebellar connections targeting motor-related regions and cortico-striatal connections mapping onto posterior parietal cortex. Thus, DCD but not DD may be considered as an impairment of cortico-subcortical functional circuits.

Sensorimotor disorders have been frequently reported in children and adults with dyslexia over the past 30 years. The present study aimed to determine the impact of sensorimotor comorbidity risks in dyslexia by investigating the functional links between phonological and sensorimotor representations in young dyslexic adults. Using 52 dyslexic participants and 58 normo-readers, we investigated whether the underlying phonological deficit, which is reported in the literature, was associated with a general impairment of sensorimotor representations of articulatory and bodily actions. Internal action representations were explored through motor imagery tasks, consisting of measuring and comparing the durations of performed or imagined actions chosen from their current repertoire of daily life activities. To detect sensorimotor deficits, all participants completed the extended version of the M-ABC 2, as a reference test. We found sensorimotor impairments in 27% of the young adult dyslexics, then considered as sensorimotor comorbid, as opposed to much less in the normo-reader group (5%). While motor slowdown, reflecting motor difficulty, was present in all dyslexic adults, motor imagery performance was impacted only in the specific dyslexic subgroup with sensorimotor impairments. Moreover, in contrast with slowness, only the comorbid subgroup showed an increased variability in execution durations. The present study highlights the importance of the quality of perception-action coupling, questions the relevance of investigating sensorimotor impairment profiles beyond phonological deficits and provides new arguments supporting the perspective of multiple deficits approaches in dyslexia.

La motricite constitue la premiere voie d’interaction entre l’individu et son environnement et reste la principale au cours des premieres annees de vie. Elle offre a ce titre un acces privilegie pour comprendre le developpement typique et atypique.Cet article presente une conception integree du developpement moteur etablie a partir du modele neuroconstructiviste. Celui-ci est dependant de la croissance et la maturation des systemes physiques et cerebraux, mais egalement des developpements perceptif, cognitif, social et affectif, que le developpement moteur influence en retour.Appliquee a la pathologie, cette approche implique qu’un trouble moteur developpemental est souvent associe a la desorganisation de dimensions variees du fonctionnement. De plus, la transition du developpement typique vers le developpement atypique des actions se realise sur un continuum. Il convient alors d’identifier les trajectoires et les cascades qui conduisent aux dysfonctionnements specifiques ainsi que les adaptations mises en place au cours du developpement. Au travers de plusieurs exemples de troubles, et en particulier le trouble de l’acquisition de la coordination, cet article illustre les mecanismes fondamentaux du developpement moteur, ainsi que leurs adaptations dans le cas du developpement atypique. Une ouverture sur les modes d’accompagnement et de prise en charge des difficultes motrices est proposee.

Anticipatory postural adjustments (APAs) cancel the destabilizing effects of movement on posture. Across development, the maturation of APAs is characterized by an accurate adjustment of the timing parameters of electromyographic (EMG) response. The study aimed at investigating the maturation of cortical oscillations involved in the improvement of APAs efficiency. Thirty-six healthy participants (8–16 yr) performed the bimanual load-lifting task in which subjects are instructed to lift a load, placed on the left forearm, with the right hand. EMG data were acquired over the biceps brachii on the postural arm to the determine EMG response onset. Electroencephalographic signals were analyzed in the time-frequency domain by convolution with complex Gaussian Morlet wavelets. Electrophysiological signature of APAs in children and adolescents consisted of a mu-rhythm desynchronization over the sensorimotor cortex contralateral to the postural arm. Across development, the mu-rhythm desynchronization was characterized by a progressive shift forward of the onset of the desynchronization, lower amplitude, and velocity. These changes occurred along with an alteration of the timing of the EMG response, as shown by an earlier onset of the flexor inhibition with increasing age. The maturational changes in the Mu-oscillations might sustain the development of APAs. A possible role of the Mu-oscillation in the generation of postural command is discussed. NEW & NOTEWORTHY Across development, our study showed a progressive shift forward of the parameters of the mu-rhythm desynchronization. These changes occurred along with an alteration of the timing parameters of the electromyographic response, as shown by an earlier onset of the flexor inhibition with increasing age. The progressive development of APAs during childhood and adolescence might therefore be sustained by maturational electrophysiological changes that include mu-rhythm oscillation modifications in the postural sensorimotor cortex.

Background and aim Feedforward and online controls are two facets of predictive motor control from internal models, which is suspected to be impaired in learning disorders. We examined whether the feedforward component is affected in children (8–12 years) with developmental dyslexia (DD) and/or with developmental coordination disorder (DCD) compared to typically developing (TD) children. Methods Children underwent a bimanual unloading paradigm during which a load supported to one arm, the postural arm, was either unexpectedly unloaded by a computer or voluntary unloaded by the subject with the other arm. Results All children showed a better stabilization (lower flexion) of the postural arm and an earlier inhibition of the arm flexors during voluntary unloading, indicating anticipation of unloading. Between-group comparisons of kinematics and electromyographic activity of the postural arm revealed that the difference during voluntary unloading was between DD-DCD children and the other groups, with the former showing a delayed inhibition of the flexor muscles. Conclusion Deficit of the feedforward component of motor control may particularly apply to comorbid subtypes, here the DD-DCD subtype. The development of a comprehensive framework for motor performance deficits in children with learning disorders will be achieved only by dissociating key components of motor prediction and focusing on subtypes and comorbidities.

International audience; Non-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.

Le controle anticipe et le controle en ligne sont les deux facettes du controle predictif, bases sur les modeles internes, qui sont suspectes d’etre impactes dans les troubles des apprentissages. Nous avons examine le controle anticipe dans une tâche bimanuelle de delestage, qui teste la coordination entre la posture du bras qui soutient le poids et le bras manipulateur qui realise le delestage, chez des enfants dyslexiques (DD) et/ou dyspraxiques (DCD), compares a des enfants au developpement typique (TD). Il ressort de cette etude une meilleure stabilisation du bras postural, basee sur une inhibition plus precoce des muscles flechisseurs au cours du delestage volontaire, traduisant ainsi l’anticipation de l’effet destabilisateur du delestage, pour l’ensemble des sujets. En revanche, seul le groupe avec une comorbidite DD/DCD, presente une anticipation des muscles flechisseurs moins precoce que les autres groupes (Cignetti et al., 2018). Ainsi cette tâche permet de reveler que sans contrainte temporelle, tous les enfants sont capables de construire une representation interne de leur action, y compris les enfants DCD. Par ailleurs, lorsque les contraintes temporelles sont tres elevees, comme dans le cas d’un apprentissage moteur en 60 essais, les enfants DCD et DD/DCD presentent des performances moins elevees. La question de la comorbidite, qui est de plus en plus renseignee dans la litterature, permet de nuancer certains resultats anterieurs et devient une veritable question en matiere d’etiologie et de remediation.

Introduction La question posee chez le jeune adulte dyslexique est de savoir si une atteinte des representations phonemiques (imprecision des representations ou difficulte d’acces) est assortie d’une atteinte plus generale des representations internes de l’action. Materiel et methodes Pour repondre a cette question, nous avons teste 45 dyslexiques et 45 normolecteurs âges de 19 a 24 ans avec un protocole d’ideation motrice assorti d’une etude detaillee du controle postural. Au prealable la motricite manuelle fine et la motricite globale ont ete evaluees au moyen du MABC2 dans sa version etendue de 3 a 17 ans, pour tous les sujets. Diverses epreuves impliquant l’ensemble du corps, les membres superieurs ou encore le systeme articulatoire ont ete proposes. Le sujet chronometre lui-meme son action qu’elle soit executee ou imaginee. Resultats Les sujets normolecteurs presentent une isochronie dans les deux situations executee et imaginee pour les epreuves de locomotion, de redressement (assis-debout), de saisie d’objet, et de repetition de phrase, ce qui atteste la robustesse de la representation interne de l’action (Chabeauti et al., 2012). Les acquisitions des sujets dyslexiques sont en cours. Discussion/conclusion Au-dela des comparaisons des durees d’execution entre les deux groupes, qui pourraient traduire un ralentissement des sujets dyslexiques, et ainsi elargir le probleme de reglage temporel du controle phonemique au controle moteur, nous cherchons a determiner si cette isochronie est affectee plus specifiquement chez certains adultes dyslexiques, presentant des troubles moteurs detectes avec le MABC2, qui pourrait traduire un deficit plus global des representations sensorimotrices.

Introduction De nombreuses etudes rapportent que la scoliose idiopathique de l’adolescent (SIA) s’accompagne d’un defaut d’integration centrale des informations sensorielles [1] , [2] , [3] , [4] . Methode Afin de mieux comprendre si les processus d’integration proprioceptive sont impactes chez les sujets atteints de SIA, nous avons explore les bases neurales de l’integration proprioceptive en IRMf de stimulation, par vibration tendineuse, chez les enfants et les adolescents au developpement typiques [5] , [6] ainsi que chez 13 adolescents atteints de SIA (Assaiante et al., en preparation). La question principale etait de savoir si les reseaux responsables de l’integration proprioceptive presentent un dysfonctionnement ou un retard de maturation dans le cas de la scoliose. Resultats Il ressort de nos etudes neurodeveloppementales que les cartes d’activation cerebrales consecutives aux vibrations tendineuses rapportent des activations similaires chez les adolescents SIA, les enfants typiques et adolescents typiques, suggerant ainsi que les principaux reseaux impliques dans la construction de la representation du corps sont actifs et preserves. Neanmoins, les adolescents SIA presentent un pattern de connectivite fonctionnelle frontostriatale et frontoparietale plus diffus que les adolescents typiques ainsi qu’une epaisseur corticale des cortex frontaux et parietaux plus importante, rappelant ainsi les caracteristiques des sujets plus jeunes. Discussion/conclusion Plutot qu’un dysfonctionnement, ces resultats semblent etre plus en faveur d’un retard de maturation des reseaux qui contribuent a construire et a reactualiser la representation du corps en action.

There is evidence that adolescence is a critical period in development, most likely involving important modifications of the body schema and of the sensorimotor representations. The present study addressed this issue, by investigating the differences between adolescents and adults regarding the integration of proprioceptive information at both perceptual and postural levels and the visual recognition of human movement. Proprioceptive integration was examined using muscle-tendon vibration that evoked either a postural response or an illusory sensation of movement. The ability to recognize human movement was investigated from a paradigm where the participants had to discern between human movements performed with and without gravity. The study produced three main findings. First, the adolescents had larger postural responses to tendon vibrations than the adults, with visual information enabling them to reduce this exaggerated postural reaction. Second, the adolescents had a greater illusory perception of movement compared with the adults. Third, the adolescents had the same perceptual ability as adults in the human movement perception task. In conclusion, we were able to highlight notable differences between adolescents and young adults, which confirms the late maturation of multisensory integration for postural control and the privileged visual contribution to postural control.

El desarrollo de las estrategias de mantenimiento del equilibrio postural y locomotor durante la infancia y la adolescencia no es lineal. Dichas estrategias alcanzan su madurez en la edad adulta. En el transcurso de esta larga adquisicion se observan varios periodos de transicion. Numerosos factores contribuyen de manera determinante en la buena (normal) o mala (patologica) adquisicion de las estrategias posturales y locomotrices. Las caracteristicas filogeneticas y ontogeneticas, el aprovechamiento de las informaciones sensoriales, la estabilizacion cefalica y pelvica, ademas del gasto atencional, son factores que deben considerarse para comprender los patrones del desarrollo postural y locomotor en el ser humano. Suele suceder que algunas anomalias como la marcha digitigrada, la torsion del esqueleto, la enfermedad motriz cerebral o el autismo perturban el desarrollo postural, por lo que es fundamental profundizar en su conocimiento.

International audience; This kinematic study investigated the effects of visual factors on the angular oscillations of the head and trunk during various locomotor tasks in 3- to 8-yr.-old children and adults. The oscillations of the head under normal vision were limited and changed little across ages. Oscillations of both head and trunk about the roll axis were the most sensitive to difficulty in maintaining lateral equilibrium. On narrow supports, the lateral oscillations of the trunk increased between the ages of 3 and 6 years, with a maximum amplitude at the latter age and then decreased up to adulthood, suggesting a transition phase around the age of 6 years. Visual restriction had little effect on the control of angular oscillations of the head in children or adults. On a narrow support in darkness, adults increased oscillations of the trunk but reduced oscillations of the head. It can be concluded that, regardless of the age, control of locomotor equilibrium aims at limiting the angular oscillations of the head. Vision seems to contribute little to stabilization of the head.

Optic flow provides visual self-motion information and is shown to modulate gait and provoke postural reactions. We have previously reported an increased reliance on the visual, as opposed to the somatosensory-based, egocentric frame of reference (FoR) for spatial orientation with age. In this study, we evaluated FoR reliance for self-motion perception with respect to the ground surface. We examined how effects of ground optic flow direction on posture may be enhanced by an intermittent podal contact with the ground, and reliance on the visual FoR and aging. Young, middle-aged and old adults stood quietly (QS) or stepped in place (SIP) for 30s under static stimulation, approaching and receding optic flow on the ground and a control condition. We calculated center of pressure (COP) translation and optic flow sensitivity was defined as the ratio of COP translation velocity over absolute optic flow velocity: the visual self-motion quotient (VSQ). COP translation was more influenced by receding flow during QS and by approaching flow during SIP. In addition, old adults drifted forward while SIP without any imposed visual stimulation. Approaching flow limited this natural drift and receding flow enhanced it, as indicated by the VSQ. The VSQ appears to be a motor index of reliance on the visual FoR during SIP and is associated with greater reliance on the visual and reduced reliance on the egocentric FoR. Exploitation of the egocentric FoR for self-motion perception with respect to the ground surface is compromised by age and associated with greater sensitivity to optic flow.

Proprioceptive processing is important for appropriate motor control, providing error-feedback and internal representation of movement for adjusting the motor command. Although proprioceptive functioning improves during childhood and adolescence, we still have few clues about how the proprioceptive brain network develops. Here, we investigated developmental changes in the functional organization of this network in early adolescents (n = 18, 12 ± 1 years), late adolescents (n = 18, 15 ± 1), and young adults (n = 18, 32 ± 4), by examining task-evoked univariate activity and patterns of functional connectivity (FC) associated with seeds placed in cortical (supramarginal gyrus) and subcortical (dorsal rostral putamen) regions. We found that although the network is already well established in early adolescence both in terms of topology and functioning principles (e.g., long-distance communication and economy in wiring cost), it is still undergoing refinement during adolescence, including a shift from diffuse to focal FC and a decreased FC strength. This developmental effect was particularly pronounced for fronto-striatal connections. Furthermore, changes in FC features continued beyond adolescence, although to a much lower extent. Altogether, these findings point to a protracted developmental time course for the proprioceptive network, which breaks with the relatively early functional maturation often associated with sensorimotor networks.

International audience; During action, Anticipatory Postural Adjustments (APAs) cancel the consequences of a movement on postural stabilization. Their muscular expression is characterized by early changes in the activity of the postural muscles, before the movement begins. To explore the mechanisms enabling the acquisition of APAs, a learning paradigm was designed in which the voluntary lifting of a load with one hand triggered the unloading of another load suspended below the contralateral forearm. The aim of this study was to investigate changes in the muscular expression that uncovers the progressive learning of new APAs. A trial-by-trial analysis of kinematic and electromyographic signals recorded on the right arm was conducted in twelve adults through six sessions of learning. Kinematic results reported an enhancement of the postural stabilization across learning. The main EMG pattern found during learning consisted of a flexor inhibition, where latency was shifted towards an earlier occurrence in parallel with the improvement of the postural performance. A linear regression analysis conducted between the inhibition latency and the maximal amplitude of elbow rotation showed that the earlier the inhibition onset, the better the postural stabilization. This study revealed that the progressive shift of the postural flexor inhibition latency could be considered as a reliable neurophysiological marker of the progressive learning of new APAs. Importantly, this marker could be used to track motor learning abnormalities in pathology. We relate our findings to the update of a forward predictive model of action, defined as a system that predicts beforehand the consequences of the action on posture.

Resume Les troubles du spectre de l’autisme (TSA) se caracterisent par des alterations qualitatives dans les relations sociales et dans la communication tant verbale que non verbale. Dans cette etude, nous avons evalue si les enfants atteints de TSA utilisent les informations relatives au corps en mouvement pour categoriser des scenes avec ou sans interactions sociales. Les performances des enfants avec TSA ont ete comparees a celles d’enfants de developpement typique apparies en âge mental non verbal et en âge chronologique. Le modele minimaliste de Johansson a ete utilise afin d’isoler les indices sociaux issus de la cinematique du corps. Ces animations illustrant deux acteurs, engages ou non dans une interaction sociale, ont ete proposees aux participants. Nos resultats soulignent les competences des enfants avec TSA a extraire de l’information sociale a partir de mouvements corporels bien qu’ils soient moins performants que des enfants de developpement typique apparies. Cette difference ne s’explique ni par un deficit du traitement configural, ni par leur niveau intellectuel, ni meme par les aspects emotionnels des scenes observees. L’interpretation de ces resultats s’appuie sur un deficit de la construction des representations de l’action et du developpement du mecanisme miroir dans l’autisme. En conclusion, le modele de Johansson se revele etre un outil pertinent et prometteur a developper dans une perspective de remediation cognitive.

Our scientific activity is focused on the field of action and representation of action from various adaptative situations during the life span, including pathology and extreme environment such as microgravity. The early action/perception matching, subserving the motor simulation network, is probably a major milestone for the building of action and representation of action during the course of ontogenesis. We have developed a functional approach of motor development based on a gradual mastering of coordination, adaptation and anticipation in postural control in the course of ontogenesis from babies to adolescents. This functional approach is recently associated with studies of brain structures involved in action and representation of action in children and adolescents with typical or atypical neurodevelopment. From our developmental studies, it was possible to put in light two turning points during motor development, such as 6/7 years of age and adolescence. The first step for children consists in building a repertoire of postural strategies. The second step consists in learning to select postural strategy depending on the characteristics of the task and the environmental requirements. An appropriate selection means to anticipate the consequence of the movement in order to maintain balance control and efficiency of the task. Taking into account the complexity of the parameters to control and the late maturation of anticipation and representation of action, it is not surprising that the development of postural control continues up to late periods during childhood and adolescence.

Resume Comprendre une interaction sociale que l’on observe necessite d’interpreter les actions realisees, parfois uniquement sur la base d’une analyse subtile du langage corporel. L’objectif de cette etude a ete de determiner le decours developpemental de l’aptitude a utiliser les informations portees par le corps en action pour comprendre une interaction sociale. Afin d’isoler les indices sociaux issus de la cinematique du corps en action, le modele minimaliste de Johansson (1973) a ete utilise. Des animations silencieuses de 3 secondes en points lumineux animes illustrant deux acteurs engages ou non dans une interaction sociale ont ete proposees a 36 enfants, âges de 4 a 10 ans. Nos resultats montrent que des l’âge de 4 ans, le corps en action se revele un indice clef dans la comprehension des interactions sociales, avec une amelioration notable aux alentours de 7-8 ans. En conclusion, cette etude comportementale montre l’existence d’une capacite precoce a extraire du langage corporel un contenu social qui s’accompagne d’un perfectionnement au cours de l’enfance. Cette capacite serait intimement liee au developpement des representations de l’action et vraisemblablement a rapprocher du developpement du mecanisme miroir.

La construction chez l’enfant et l’adolescent des representations de l’action, qui comprend le developpement du schema corporel et le repertoire des strategies motrices, constitue une ligne de recherche privilegiee pour notre groupe. Nous abordons le developpement moteur a partir d’une approche fonctionnelle qui resulte, au cours des differentes etapes de la vie, de la maitrise progressive de la fonction de coordination entre posture et mouvement, de la fonction d’anticipation qui permet de predire les effets perturbateurs lies au mouvement sur la base d’une representation interne et de la fonction d’adaptation qui permet de prendre en compte le contexte environnemental dans lequel se deroule l’action. L’ensemble de nos etudes developpementales a contribue a mettre en evidence des periodes dites « charnieres » au cours du developpement moteur, telles que 6/7 ans et l’adolescence. Si la premiere etape pour l’enfant consiste a construire les elements de son repertoire moteur, la deuxieme etape consiste a apprendre a selectionner les elements pertinents de ce repertoire, en fonction de l’action a executer et du contexte environnemental. Selectionner la strategie appropriee revient a anticiper les consequences de l’action dans le but de preserver l’efficacite du geste. L’anticipation se developpe tardivement au cours de l’enfance, en meme temps que se construisent les representations de l’action. Dans ces conditions, il n’est pas etonnant que le developpement moteur soit particulierement long au cours de l’ontogenese et perdure au-del a de l’adolescence.

Introduction La posture est consideree comme un element essentiel dans la phonation pour optimiser la communication. En situation de forcage vocal, lorsque le locuteur doit surmonter des difficultes comme la distance de son auditeur, son inattention ou le bruit ambiant, des modifications globales apparaissent au niveau de la posture, telle que la perte de la verticalite et de l’alignement postural. Une perturbation fonctionnelle de la coordination posture-voix peut alors amener le sujet a utiliser des solutions posturales generatrices de tensions. Le but de cette etude est de determiner si les mouvements du corps sont une consequence de l’effort vocal ou bien une strategie a part entiere pour optimiser l’effort de communication. Materiel et methode Nous avons entrepris une etude de correlations entre les marqueurs de la phonation, enregistres au moyen du systeme d’enregistrement EVA (SQLab, LPL, Aix-en-Provence) et ceux de la posture, enregistres au moyen d’un systeme automatique d’analyse de mouvement (SMART) chez 20 jeunes femmes realisant trois tâches de communication verbale avec des difficultes croissantes d’effort vocal. Resultats Les parametres vocaux augmentent effectivement en fonction des difficultes de l’environnement de communication. Les parametres cinematiques (amplitudes et durees des mouvements corporels) augmentent avec l’effort vocal. Enfin, parametres vocaux et cinematiques sont intimement correles avec une anticipation posturale. Discussion/Conclusion Ainsi, tâches posturale et vocale sont coordonnees et l’anticipation posturale est consideree comme une veritable strategie de communication qui consiste a capter l’attention de l’auditeur afin qu’il puisse se focaliser sur le contenu du message [1] .

AIM 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.

Most striking in a child with autism is the absence, or the alteration, of communication. Meanwhile, an essential aspect of motor development is to achieve a fundamental adaptive function: communication. This is enabled by a constant dialog between a child and its environment, in particular through sensory-motor stimulations, and already at a very early age. Our approach relies on the hypothesis of a general deficit in the building up of action representations in autism. We present some studies aimed at studying the development of the function of anticipation that enables the world to be predictable and coherent. To anticipate, the brain needs some representations of the body characteristics, the external world and their reciprocal interactions. Action representations are not innate and they need time to mature during childhood. Exploring some motor parameters and their cortical correlates in lifting tasks, we found that the function of anticipation is altered in autism, which might indicate a deficit in the building of action representations. Finally, the question of human motion representation, in particular within the context of social interaction is also questioned in autism, as well as which structures are involved. The coupling between action and perception strongly depending on the building of multiple representations (including body scheme, the representation of the feasibility of a movement and the representation of the meaning of an action), our hypothesis is that impairments in the building-up of representation perturb this coupling and consequently slow down the sensory-motor and cognitive development in autism., Un aspect majeur de l'autisme réside dans l'altération des capacités de communication. Or, une des fonctions essentielles de la motricité est, précisément, de permettre le dialogue entre l'organisme et son environnement, notamment au travers des entrées sensorielles, et ce dès le plus jeune âge. C'est dans le cadre de l'hypothèse d'une atteinte générale de la construction des représentations de l'action dans l'autisme que nous rapportons un ensemble de résultats visant à étudier chez l'enfant le développement de la fonction d'anticipation qui permet de rendre le monde prédictible et cohérent. Pour anticiper, le cerveau s'appuie sur des représentations des caractéristiques du corps, du monde extérieur et de leurs interactions réciproques. Les représentations de l'action ne sont pas innées et nécessitent un temps de maturation assez long au cours de l'enfance. A partir de tâches de soulèvement alliant paramètres moteurs et corrélats corticaux, on constate chez l'enfant avec autisme un déficit de la fonction d'anticipation, d'origine centrale, qui indiquerait une atteinte de la construction des représentations de l'action. Enfin se pose actuellement la question dans l'autisme de la représentation du mouvement humain, en particulier dans un contexte d'interactions sociales, et de l'identification des structures centrales impliquées. Sachant que le couplage entre la perception et l'action dépend fortement de la construction de multiples représentations (incluant le schéma corporel, la représentation de la faisabilité du mouvement et la représentation de l'action dans sa globalité), nous faisons l'hypothèse qu'une atteinte de la construction des représentations perturbe ce couplage et en conséquent freine le développement sensori-moteur et cognitif dans l'autisme.

In the current study, we adopted the hypothesis that the body scheme disturbances occurring during adolescence might lead subjects to transiently neglect proprioceptive information and that adolescents might rely more strongly on vision to control their orientation and stabilize their body. To check this point, we asked adolescents 14–15 years to maintain vertical stance while very slow sinusoidal oscillations in the frontal plane were applied to the supporting platform at 0.01 Hz (below the detection threshold of the semicircular canal system) and at 0.06 Hz (above) with the eyes open and closed. Two postural components, orientation and segmental stabilization, were analyzed at the head, shoulder, trunk, and pelvis levels. At the lowest frequency without vision, the performances of adolescents were much less efficient than those of adults. Moreover, this study showed that vision plays a predominant role in adolescents’ control of orientation and body stabilization. At 0.06 Hz without vision, a clearcut difference was observed between the strategies used by girls and boys; specifically, the maturation of the segmental stabilization processes was found to be more advanced in girls than in boys. However, no such difference was observed at 0.01 Hz. Lastly, comparisons between the data obtained in adolescents and those previously obtained in young adults (Vaugoyeau, Viel, Amblard, Azulay, & Assaiante, 2008) clearly show that adolescents use different postural strategies and that they are not yet capable of reaching comparable postural performance levels to those observed in adults. Because adolescents were not able to use the proprioceptive information available to improve their postural control, we concluded that they showed a maturational lag in comparison with adults. This suggests that the mechanisms underlying postural control are still maturing during adolescence, which might constitute a transient period of proprioceptive neglect in sensory integration of postural control.

Study design Locomotor balance control assessment was performed to study the effect of idiopathic scoliosis on head-trunk coordination in 17 patients with adolescent idiopathic scoliosis (AIS) and 16 control subjects. Objective The aim of this study was to explore the functional effects of structural spinal deformations like idiopathic scoliosis on the balance strategies used during locomotion. Summary of background data Up to now, the repercussion of the idiopathic scoliosis on head-trunk coordination and balance strategies during locomotion is relatively unknown. Methods Seventeen patients with AIS (mean age 14 years 3 months, 10 degrees 30 degrees) and 16 control subjects (mean age 14 years 1 month) were tested during various locomotor tasks: walking on the ground, walking on a line, and walking on a beam. Balance control was examined in terms of rotation about the vertical axis (yaw) and on a frontal plane (roll). Kinematics of foot, pelvis, trunk, shoulder, and head rotations were measured with an automatic optical TV image processor in order to calculate angular dispersions and segmental stabilizations. Results Decreasing the walking speed is the main adaptive strategy used in response to balance problems in control subjects as well as patients with AIS. However, patients with AIS performed walking tasks more slowly than normal subjects (around 15%). Moreover, the pelvic stabilization is preserved, despite the structural changes affecting the spine. Lastly, the biomechanical defect resulting from idiopathic scoliosis mainly affects the yaw head stabilization during locomotion. Conclusions Patients with AIS show substantial similarities with control subjects in adaptive strategies relative to locomotor velocity as well as balance control based on segmental stabilization. In contrast, the loss of the yaw head stabilization strategies, mainly based on the use of vestibular information, probably reflects the presence of vestibular deficits in the patients with AIS.

Reliance on the visual frame of reference for spatial orientation (or visual field dependence) has been reported to increase with age. This has implications on old adults' daily living tasks as it affects stability, attention, and adaptation capacities. However, the nature and underlying mechanisms of this increase are not well defined. We investigated sensorimotor and cognitive factors possibly associated with increased visual field dependence in old age, by considering functions that are both known to degrade with age and important for spatial orientation and sensorimotor control: reliance on the (somatosensory-based) egocentric frame of reference, visual fixation stability, and attentional processing of complex visual scenes (useful field of view, UFOV). Twenty young, 18 middle-aged, and 20 old adults completed a visual examination, three tests of visual field dependence (RFT, RDT, and GEFT), a test of egocentric dependence (subjective vertical estimation with the body erect and tilted at 70°), a visual fixation task, and a test of visual attentional processing (UFOV®). Increased visual field dependence with age was associated with reduced egocentric dependence, visual fixation stability, and visual attentional processing. In addition, visual fixation instability and reduced UFOV were correlated. Results of middle-aged adults fell between those of the young and old, revealing the progressive nature of the age effects we evaluated. We discuss results in terms of reference frame selection with respect to ageing as well as visual and non-visual information processing. Inter-individual differences amongst old adults are highlighted and discussed with respect to the functionality of increased visual field dependence.

Resume Les troubles de la marche sont frequents en neurologie. Leur semiologie clinique permet parfois d'etablir des correlations anatomocliniques et d'en deduire une etiologie avec ou sans l'aide d'examens complementaires. De nombreuses classifications basees sur l’examen clinique ont ete proposees mais ne permettent pas dans de nombreux cas de trancher. L’apport des techniques recentes d’analyse quantifiee du mouvement appliquees a la locomotion ou de systemes specifiques est interessant tant au point de vue de la connaissance des mecanismes physiologiques du controle posturolocomoteur, de leur acquisition tout au long du developpement chez l’enfant que de la determination des mecanismes physiopathologiques impliques dans les troubles de la marche pathologiques ou lies au vieillissement.

International audience; The development of the ability to integrate postural adjustments into the gait initiation process was investigated in children, using both kinematic and electromyographic (EMG) analysis. Subjects included children of 1 year of age (1-4 months' walking experience), 2-3 years of age (9-17 months' walking experience), 4-5 years of age (3-4 years' walking experience), and adults. We perturbed the balance of the children during gait initiation to determine the point at which infants begin to develop and finally master the ability to respond to external threats to balance during the gait initiation process. A magnet attached to the force platform on which the child stood was activated and served to resist the child's gait initiation (metal plaques on the soles of the shoes were attracted by the magnet) and thus served as an external perturbation during the gait initiation process. Kinematic and EMG analysis indicated that, while the ability to use preparatory postural adjustments in the gait initiation process emerges early in development, the ability to react efficiently to perturbations during gait initiation does not develop until after about 4-5 years of age. Though even the youngest age groups showed some response to the perturbation, it was highly variable, indicating its primitive form. The main response to the perturbation was a slight decrease in latency and increase in amplitude in the muscles used for push-off for gait initiation. Interestingly there was a shift in response pattern at 4-5 years of age, in both kinematic and EMG patterns. The amplitudes of the lateral and anteroposterior trunk and stance leg oscillations were significantly increased. In addition, the muscle response amplitudes (hamstrings and second quadriceps burst) of the swing leg were significantly increased and delayed (hamstring and gastrocnemius), with coactivation of agonist and antagonist muscles at the knee and ankle joint, concomitant with an exaggerated foot height of the first step.

International audience; In order to perceive and act in its environment, the individual's body and its interactions with the sensory and social environment are represented in the brain. This internal representation of the moving body segments is labeled the body schema. Throughout life, body schema develops based on the sensory information used by the moving body and by its interactions with the environment including other people. Internal representations including body schema and representations of the outside world develop with learning and actions throughout ontogenesis and are constantly updated based on different sensory inputs. The aim of this review is to present some concepts and experimental data about body schema, internal representations and updating process during childhood and adolescence, as obtained using a neurosensory approach. From our developmental studies, it was possible to explore the slow maturation of the sensorimotor representations by examining the anticipatory control. By manipulating proprioceptive and visual information, which are at the heart of the construction of body schema, we wished to highlight notable differences between adolescents and young adults on both a postural and perceptual level, which confirms the late maturation of multisensory integration for central motor control.