title: Initial information prior to movement onset influences kinematics of upward arm pointing movements.
abstract: To elaborate a motor plan and perform online control in the gravity field, the brain relies on priors and multisensory integration of information. In particular, afferent and efferent inputs related to the initial state are thought to convey sensorimotor information to plan the upcoming action. Yet it is still unclear to what extent these cues impact motor planning. Here we examined the role of initial information on the planning and execution of arm movements. Participants performed upward arm movements around the shoulder at three speeds and in two arm conditions. In the first condition, the arm was outstretched horizontally and required a significant muscular command to compensate for the gravitational shoulder torque before movement onset. In contrast, in the second condition the arm was passively maintained in the same position with a cushioned support and did not require any muscle contraction before movement execution. We quantified differences in motor performance by comparing shoulder velocity profiles. Previous studies showed that asymmetric velocity profiles reflect an optimal integration of the effects of gravity on upward movements. Consistent with this, we found decreased acceleration durations in both arm conditions. However, early differences in kinematic asymmetries and EMG patterns between the two conditions signaled a change of the motor plan. This different behavior carried on through trials when the arm was at rest before movement onset and may reveal a distinct motor strategy chosen in the context of uncertainty. Altogether, we suggest that the information available online must be complemented by accurate initial information.
authors.affiliation: Université de Bourgogne Franche-Comté (UBFC), Cognition Action et Plasticité Sensorimotrice (CAPS) UMR1093, Dijon, France; Institut National de Santé et de Recherche Médicale (INSERM U1093), Cognition Action et Plasticité Sensorimotrice (CAPS) UMR1093, Dijon, France; and celiarousseau.rousseau@gmail.com.
authors.forename: Célia
authors.initials: C
authors.lastname: Rousseau
authors.affiliation: Université de Bourgogne Franche-Comté (UBFC), Cognition Action et Plasticité Sensorimotrice (CAPS) UMR1093, Dijon, France; Institut National de Santé et de Recherche Médicale (INSERM U1093), Cognition Action et Plasticité Sensorimotrice (CAPS) UMR1093, Dijon, France; and.
authors.forename: Charalambos
authors.identifier: 0000-0003-1955-8269
authors.initials: C
authors.lastname: Papaxanthis
authors.affiliation: Université de Bourgogne Franche-Comté (UBFC), Cognition Action et Plasticité Sensorimotrice (CAPS) UMR1093, Dijon, France; Institut National de Santé et de Recherche Médicale (INSERM U1093), Cognition Action et Plasticité Sensorimotrice (CAPS) UMR1093, Dijon, France; and.
authors.forename: Jérémie
authors.identifier: 0000-0001-8827-1486
authors.initials: J
authors.lastname: Gaveau
authors.affiliation: Université de Bourgogne Franche-Comté (UBFC), Cognition Action et Plasticité Sensorimotrice (CAPS) UMR1093, Dijon, France; Institut National de Santé et de Recherche Médicale (INSERM U1093), Cognition Action et Plasticité Sensorimotrice (CAPS) UMR1093, Dijon, France; and Institut Universitaire de France (IUF), Paris, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Pozzo
authors.affiliation: Université de Bourgogne Franche-Comté (UBFC), Cognition Action et Plasticité Sensorimotrice (CAPS) UMR1093, Dijon, France; Institut National de Santé et de Recherche Médicale (INSERM U1093), Cognition Action et Plasticité Sensorimotrice (CAPS) UMR1093, Dijon, France; and.
authors.forename: Olivier
authors.initials: O
authors.lastname: White
mesh_terms: D000328:Adult; D001132:Arm / Q000502:physiology*; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D006112:Gravitation; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009068:Movement / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D011434:Proprioception; D012782:Shoulder / Q000502:physiology*; D019415:Torque; D014796:Visual Perception; D055815:Young Adult
keywords: arm movement; gravitational force; initial information; motor planning