Maturation et apprentissage du contrôle postural anticipé au cours de l’adolescence : Expressions motrice et cérébrale
auteurs
mots-clés
- Cognitive neuroscience
- Neurosciences cognitives
type de document
THESErésumé
In order to achieve a specific goal, voluntary action requires an anticipatory behaviour,which predicts the consequence of the planned action on the postural control. Anticipatorybehaviour rests on action and body representations, which are in continual evolution acrosslife. Under hormonal influences, adolescence is characterized by body modifications andcerebral maturation. This thesis explored the link between the anticipatory function, action andbody representations, and the cerebral maturation during this key period.Anticipatory function was assessed using the bimanual load-lifting task, which engages apostural arm, supporting the load, and a motor arm, lifting the load. In this task, theanticipatory behaviour is expressed by anticipatory postural adjustments (APAs). Characterizedby an earlier inhibition of the postural flexors in adults, APAs cancel the destabilizing effect ofmovement on the postural reference. Kinematics, electromyographic andelectroencephalographic recordings were simultaneously used to explore the maturation andthe building of a sensorimotor representation during the adolescence.Although performances of postural stabilization were stable, APAs at the adolescencewere characterized by an earlier occurrence of the inhibition latency on the postural flexors. Inadults, the APAs are expressed by a mu rhythm desynchronization and a positive wave overthe sensorimotor cortex involved in postural stabilization. The electrophysiological signaturesrecorded in the adolescent group presented different temporal characteristics. Thus, theimprovement of the anticipatory function would be underlain by a maturation of theseelectrophysiological activities during the adolescence.Learning a new postural control was characterized, in adults as well as in adolescents,by a rapid followed by a slow improvement of the postural stabilisation. The acquisition ofanticipatory control rested on the mastering of the temporal parameters of the flexorsinhibition, which took more time during the adolescence. Integration of the proprioceptivefeedback coming from the action is the mechanism at the origin of the update of thesensorimotor representation.Expressed by the mastering of the temporal parameters, the update of the body andaction representations during the adolescence would imply an enhancement of the integrationof proprioceptive information, which would be still lacking at the adolescence. The maturationof the cerebral areas involved in these representations would be also a key element.
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