Developmental Coordination Disorder (DCD) corresponds to a clumsiness, a slowness and an inaccuracy of motor performance. This neurodevelopmental disorder affects 6% of school-aged children, and disturbs daily life activities and academic performances. The etiology of DCD is still unknown. An understanding of this disorder is necessary to improve interventions and therefore quality of life of these people.

A deficit of the so-called internal models is the most commonly described hypothesis of DCD. Indeed, children with DCD exhibit difficulties in predictive control. Internal models, useful for motor control, are closely related to the sensory system, as they are elaborated on and constantly fed by sensory feedback. Deficits in sensory performance are described in DCD, mostly in the visual system, which could in turn partly explain poor motor performance. However, visuo-perceptual deficits cannot explain the entire motor difficulties because some activities in daily life, as buttoning a shirt, are often performed without visual control. Although the integrity of proprioceptive and tactile systems is necessary for the building of internal models, and therefore for a stable motor control, these sensory systems have been very little investigated in DCD.

Moreover, using a tool is often disturbed in children with DCD. In neurotypical subjects, tool use induces a plasticity of body representation, as reflected by modifications of movement kinematics after tool use. Proprioceptive abilities are necessary for this update of the body schema. Thus, potential deficits of the proprioceptive system in children with DCD could impair the plastic modification of the body schema, and hence of motor performance, when using a tool. The aim of this study is to identify the main cause of the DCD, both by evaluating the tactile and proprioceptive abilities and by assessing the body schema updating abilities in children with DCD.

While some daily life activities improve with age, some motor difficulties persist in adults with DCD. To our knowledge, perceptual abilities have never been investigated in adults with DCD and it is thus unknown whether perceptual deficits are still present in adulthood. This information could allow us to understand if motor difficulties in adult DCD are caused by enduring perceptual deficits and/or impaired plasticity of body schema. The second aim of this study is to evaluate abilities of perception and of body schema plasticity in adults with DCD.

Inclusion Criteria:

• Male or female
• Aged 9 to 11 or 18 to 40
• Affiliated to a health care organism
• Signed written informed consent (adult subjects)
• One of the legal guardians of children subjects providing their free, informed and written consent to participate in the study; With the child also giving orally his consent to participate.

For participants with Developmental coordination disorder:

• Subjects fulfilling the diagnostic criteria for dyspraxia of DSM-5 (these criteria will be verified by the principal investigator)
• Total MABC-2 score below the 15th percentile (if this MABC-2 assessment is already available).

Exclusion Criteria:

• Prematurity
• Known neurological pathology (other than dyspraxia)
• Intellectual disability
• Visual impairment
• Surgery or trauma to the upper limbs that has occurred too recently to allow proper testing
• Subject under tutorship or curatorship
• Subject deprived of liberty by a judicial or administrative decision

For healthy volunteers only:

- History of developmental coordination disorder in close relatives (parents, children, siblings).