Reaching in Children with and without Developmental Coordination Disorder (DCD) under normal and perturbed vision

The aim of this study is to describe the reaching action of children with developmental coordination disorder (DCD) and to investigate whether their use of visual feedback during the time course of this action differs from that of normally developing children. Fifty-two children subdivided into 2 age bands (7-8 and 9-10 years) within 2 groups (with and without DCD) participated in this experiment. They were asked to reach for a target positioned either ipsilaterally or contralaterally to the reaching hand in 2 visual conditions: a condition where vision was unrestrained (normal vision) and a condition where they wore glasses with prismatic lenses (perturbed vision). An analysis of the experimental data indicates that the trajectories followed by the DCD group were longer and more curved than those of the control group. Further, the deceleration times were longer for the DCD group than for the normally developing children. The introduction of the prismatic lenses supports the idea that the use of visual feedback by children with DCD may be different from that in children without DCD

D\ue9veloppement de l\u2019action planifi\ue9e chez le f\u153tus humain

\uc0 partir de quand un mouvement cesse-t-il d'\ueatre un r\ue9flexe pour acqu\ue9rir les caract\ue9ristiques de l'action volontaire ? L'interaction dynamique entre l'\ueatre humain et son environnement est-elle d\ue9j\ue0 pr\ue9sente avant la naissance ? L'\ue9tude des mouvements f'taux repr\ue9sente une occasion unique pour tenter de r\ue9pondre \ue0 ces questions en observant l'\ue9volution des mouvements des membres sup\ue9rieurs. Durant la gestation il y a des diff\ue9rences dans la fr\ue9quence des mouvements dirig\ue9s vers les diff\ue9rentes parties de la t\ueate, mais les mouvements de la main vers la bouche et les yeux semblent les plus fr\ue9quents. La pr\ue9sence de ces deux cat\ue9gories de mouvements \ue0 diff\ue9rents stades de la gestation permet d'\ue9tudier si une intentionnalit\ue9 dans le mouvement des membres sup\ue9rieurs appara\ueet \ue0 un certain moment de la p\ue9riode foetale. Cet objectif a \ue9t\ue9 suivi dans deux recherches. La premi\ue8re a pris en consid\ue9ration 8 grossesses monof'tales et la deuxi\ue8me 5 grossesses g\ue9mellaires. Dans la premi\ue8re recherche, les mouvements foetaux de la main ont \ue9t\ue9 enregistr\ue9s \ue0 la 14e, 18e et 22e semaine gestationnelle, alors que dans la deuxi\ue8me les mouvements n'ont pu \ueatre enregistr\ue9s qu'\ue0 la 14e et 18e semaine. L'enregistrement \ue9chographique pour chaque \ue2ge gestationnel a \ue9t\ue9 de 20 minutes. Il a \ue9t\ue9 analys\ue9 en utilisant un logiciel d\ue9velopp\ue9 sp\ue9cialement pour extraire, off-line, les param\ue8tres cin\ue9matiques : temps de d\ue9c\ue9l\ue9ration et temps de mouvement. Les r\ue9sultats sugg\ue8rent que les foetus, de grossesses simples ou g\ue9mellaires, peuvent ajuster le mouvement de la main en fonction de la cible \ue0 atteindre, sans doute en utilisant les diff\ue9rentes sensations de leurs organes sensoriels. Il semble donc que le f'tus \uab reconnaisse \ubb que la bouche est une cible moins d\ue9licate que ses yeux et que donc il peut s'en approcher plus rapidement que lors d'un mouvement vers l'oeil. En outre l'analyse temporelle des mouvements de la main vers le jumeau permet de v\ue9rifier que le contact vers le jumeau n'est pas accidentel et seulement d\ufb \ue0 la proximit\ue9 spatiale, mais volontairement dirig\ue9 vers lui. Ces donn\ue9es pr\ue9liminaires mettent en \ue9vidence la pr\ue9sence dans les mouvements des membres sup\ue9rieurs du f'tus d'une forme primitive d'action intentionnelle, avec un pattern cin\ue9matique qui varie en fonction de l'objectif de l'action

A comparison of the reach-to-grasp movement between children and adults: a kinematic study

In this study, the reach-to-grasp movement of 5-year-old children was compared to that of adults. Participants were required to reach out and grasp objects, with and without on-line visual feedback. Object size and distance were covaried in a within-subjects design and it was found that for both groups, grip formation and reach kinematics were affected by the manipulation of either variable. Although there are a large number of similarities, a few differences between the two groups emerge. For the reaching component, the children revealed a longer movement duration and deceleration time and a lower maximum height of wrist trajectory than in adults. For the grasp component, the children, in both the vision and no-vision condition, show a maximal finger aperture larger than the adults. Further, the children of this study were able to scale their grip aperture according to object size when visual feedback during the movement was lacking. These findings suggest that children adopt different strategies than adults when planning a reach-to-grasp movement on the basis of object size, distance, and the predictability of visual feedback. The results are discussed in terms of the neural mechanisms underlying hand action and how these mechanisms may not be fully developed by the age of 5

Evidence of early development of action planning in the human foetus: a kinematic study

The aim of the present study was to investigate whether foetal hand movements are planned and how they are executed. We performed a kinematic analysis of hand movements directed towards the mouth and the eyes in the foetuses of eight women with normally evolving pregnancies. At 14, 18 and 22 weeks of gestation, eight foetuses underwent a 20-min four-dimensional-ultrasound session. The video recordings for these movements were then imported into in-house software developed to perform kinematic analysis. We found that spatial and temporal characteristics of foetal movements are by no means uncoordinated or unpatterned. By 22 weeks of gestation the movements seem to show the recognizable form of intentional actions, with kinematic patterns that depend on the goal of the action, suggesting a surprisingly advanced level of motor planning

Wired to Be Social: The Ontogeny of Human Interaction.

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Wired to Be Social: The Ontogeny of Human Interaction

Background: Newborns come into the world wired to socially interact. Is a propensity to socially oriented action already present before birth? Twin pregnancies provide a unique opportunity to investigate the social pre-wiring hypothesis. Although various types of inter-twins contact have been demonstrated starting from the 11th week of gestation, no study has so far investigated the critical question whether intra-pair contact is the result of motor planning rather then the accidental outcome of spatial proximity. Methodology/Principal Findings: Kinematic profiles of movements in five pairs of twin foetuses were studied by using four-dimensional ultrasonography during two separate recording sessions carried out at the 14th and 18th week of gestation. We demonstrate that by the 14th week of gestation twin foetuses do not only display movements directed towards the uterine wall and self-directed movements, but also movements specifically aimed at the co-twin, the proportion of which increases between the 14th and 18th gestational week. Kinematic analysis revealed that movement duration was longer and deceleration time was prolonged for other-directed movements compared to movements directed towards the uterine wall. Similar kinematic profiles were observed for movements directed towards the co-twin and selfdirected movements aimed at the eye-region, i.e. the most delicate region of the body. Conclusions/Significance: We conclude that performance of movements towards the co-twin is not accidental: already starting from the 14th week of gestation twin foetuses execute movements specifically aimed at the co-twin