The cost of moving optimally: kinematic path selection

D.A. Kistemaker, J.D. Wong, P.L. Gribble

    Research output: Contribution to JournalArticleAcademicpeer-review

    Abstract

    It is currently unclear whether the brain plans movement kinematics explicitly or whether movement paths arise implicitly through optimization of a cost function that takes into account control and/or dynamic variables. Several cost functions are proposed in the literature that are very different in nature (e.g., control effort, torque change, and jerk), yet each can predict common movement characteristics. We set out to disentangle predictions of the different variables using a combination of modeling and empirical studies. Subjects performed goal-directed arm movements in a force field (FF) in combination with visual perturbations of seen hand position. This FF was designed to have distinct optimal movements for muscle-input and dynamic costs while leaving kinematic cost unchanged. Visual perturbations in turn changed the kinematic cost but left the dynamic and muscle-input costs unchanged. An optimally controlled, physiologically realistic arm model was used to predict movements under the various cost variables. Experimental results were not consistent with a cost function containing any of the control and dynamic costs investigated. Movement patterns of all experimental conditions were adequately predicted by a kinematic cost function comprising both visually and somatosensory perceived jerk. The present study provides clear behavioral evidence that the brain solves kinematic and mechanical redundancy in separate steps: in a first step, movement kinematics are planned; and in a second, separate step, muscle activation patterns are generated.
    Original languageEnglish
    Pages (from-to)1815-24
    JournalJournal of Neurophysiology
    Volume112
    Issue number8
    Early online date18 Jun 2014
    DOIs
    Publication statusPublished - 2014

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    Biomechanical Phenomena
    Costs and Cost Analysis
    Muscles
    Arm
    Cost Control
    Brain
    Torque
    Hand

    Cite this

    Kistemaker, D.A. ; Wong, J.D. ; Gribble, P.L. / The cost of moving optimally: kinematic path selection. In: Journal of Neurophysiology. 2014 ; Vol. 112, No. 8. pp. 1815-24.
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    The cost of moving optimally: kinematic path selection. / Kistemaker, D.A.; Wong, J.D.; Gribble, P.L.

    In: Journal of Neurophysiology, Vol. 112, No. 8, 2014, p. 1815-24.

    Research output: Contribution to JournalArticleAcademicpeer-review

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