title: Age-related differences in the reaching and grasping coordination in children: unimanual and bimanual tasks.
abstract: This study examined age-related differences in the coordinative mechanism of the reach-to-grasp movement in three groups of children aged 6, 8, and 11 year, and in healthy adults. Three prehension conditions were manipulated: an unimanual and a bimanual self-driven tasks in which the reaching and grasping of the object were performed by participants, and a bimanual externally-driven task, in which the experimenter brought the object into the vicinity of the participant which grasped it. Classical kinematics data-peak velocities of the reaching and the grasping, the time to onset grip opening, maximum grip opening and grip closure-were calculated. Moreover, to obtain equivalent kinematics variables for all age groups, relative time to peak velocity (% of reaching duration), relative maximum grip opening (% of object size), and percentage of the four types of phase plans between reaching velocity and grip size have been calculated for each group of age. Our main results showed (1) a high variability at age 6, (2) an age-related change between the 6- and 8-year old for almost all of the dependent variables, and (3) a significant difference between the 11-year olds and adults. In summary, at 6 years, the interdependence between the reaching and grasping programs was unstable. A transitory feedback-based coordination between reaching and grasping appeared at 8 years of age. Finally, the adults' relationship between reaching and grasping was not attained at the age of 11.
authors.affiliation: Laboratoire TIMC, Equipe Santé Plasticité Motricité, UMR CNRS 5525, UFR APS, Université Joseph Fourier, BP 53 X, 38 041 Grenoble Cedex, France. Isabelle.Olivier@ujf-grenoble.fr
authors.forename: Isabelle
authors.initials: I
authors.lastname: Olivier
authors.forename: Laurette
authors.initials: L
authors.lastname: Hay
authors.forename: Chantal
authors.initials: C
authors.lastname: Bard
authors.forename: Michelle
authors.initials: M
authors.lastname: Fleury
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology*; D001132:Arm / Q000294:innervation / Q000502:physiology*; D001696:Biomechanical Phenomena; D002648:Child; D005246:Feedback / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D009048:Motor Skills / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D009420:Nervous System / Q000254:growth & development*; D009483:Neuropsychological Tests