title: Directional constraints during bimanual coordination: the interplay between intrinsic and extrinsic directions as revealed by head motions.
abstract: The role of directional compatibility was investigated during the production of in-phase and anti-phase coordination patterns involving both arms as well as the head. Our first aim was to compare the quality of coordination between both arms when symmetrical arm posture manipulations were used to disentangle muscle homology from the mutual direction of limb motions in extrinsic space. Findings revealed that in-phase coordination, characterized by the simultaneous activation of homologous muscle groups, was resistant to posture manipulations. Conversely, during anti-phase coordination, the influence of extrinsic direction became more prevalent whereby isodirectionality in extrinsic space contributed to stabilization of anti-phase coordination patterns. The second aim was to study the effect of periodic head movements upon the assembling of a coordinative synergy among the body segments. The findings demonstrated that the in-phase patterns were hardly affected by directionality of head motion. Conversely, the anti-phase patterns were more vulnerable to the directional influence of head movements, showing less accurate and stable coordination during non-isodirectional than isodirectional head motions. These observations underscore the robust nature of coordination patterns based on muscle homology, even in the absence of symmetric arm positions. Moreover, isodirectional head movements became easily integrated with the overall coordination pattern, whereas head-limb coupling was poor when the head moved anti-directional with the limbs.
authors.affiliation: Motor Control Laboratory, Research Center for Motor Control and Neuroplasticity, Department of Biomedical Kinesiology, K.U.L., Tervuurse Vest 101, 3001 Leuven, Belgium.
authors.forename: R L J
authors.initials: RL
authors.lastname: Meesen
authors.forename: N
authors.initials: N
authors.lastname: Wenderoth
authors.forename: J J
authors.initials: JJ
authors.lastname: Temprado
authors.forename: S P
authors.initials: SP
authors.lastname: Swinnen
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001132:Arm / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006225:Hand / Q000502:physiology; D019416:Head Movements / Q000502:physiology*; D006801:Humans; D007699:Kinesthesis / Q000502:physiology*; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D009048:Motor Skills / Q000502:physiology; D009068:Movement / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D009949:Orientation / Q000502:physiology; D004856:Postural Balance / Q000502:physiology; D012016:Reference Values; D013028:Space Perception / Q000502:physiology; D013037:Spatial Behavior / Q000502:physiology*