Properties of Synergies Arising from a Theory of Optimal Motor Behavior

  • Authors:
  • Manu Chhabra;Robert A. Jacobs

  • Affiliations:
  • Department of Computer Science, University of Rochester, Rochester, NY 14627, U.S.A.;Department of Brain and Cognitive Sciences, University of Rochester, Rochester, NY 14627, U.S.A.

  • Venue:
  • Neural Computation
  • Year:
  • 2006
  • Action

    Foundations of cognitive science

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Abstract

Studies of the motor synergies reveal several interesting findings. First, optimal motor actions can be generated by summing a small number of scaled and time-shifted motor synergies, indicating that optimal movements can be planned in a low-dimensional space by using optimal motor synergies as motor primitives or building blocks. Second, some optimal synergies are task independent—they arise regardless of the task context—whereas other synergies are task dependent—they arise in the context of one task but not in the contexts of other tasks. Biological organisms use a combination of task-independent and task-dependent synergies. Our work suggests that this may be an efficient combination for generating optimal motor actions from motor primitives. Third, optimal motor actions can be rapidly acquired by learning new linear combinations of optimal motor synergies. This result provides further evidence that optimal motor synergies are useful motor primitives. Fourth, synergies with similar properties arise regardless if one uses an arm controlled by torques applied at the joints or an arm controlled by muscles, suggesting that synergies, when considered in “movement space,” are more a reflection of task goals and constraints than of fine details of the underlying hardware.