A neural mechanism of synergy formation for whole body reaching

  • Authors:

  • Pietro Morasso;Maura Casadio;Vishwanathan Mohan;Jacopo Zenzeri

  • Affiliations:

  • Italian Inst. of Technology, Dept. of Robotics, Brain and Cognitive Sci., Genoa and Univ. of Genoa, Dept. of Informatics, Systems, Telecommunications (DIST), Via Opera Pia 13, 16145, Genoa and Nat ...;Italian Institute of Technology, Department of Robotics, Brain and Cognitive Sciences, Genoa, Italy and University of Genoa, Department of Informatics, Systems, Telecommunications (DIST), Via Oper ...;Italian Institute of Technology, Department of Robotics, Brain and Cognitive Sciences, Genoa, Italy;Italian Institute of Technology, Department of Robotics, Brain and Cognitive Sciences, Genoa, Italy and University of Genoa, Department of Informatics, Systems, Telecommunications (DIST), Via Oper ...

  • Venue:
  • Biological Cybernetics
  • Year:
  • 2010

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Abstract

The present study proposes a computational model for the formation of whole body reaching synergy, i.e., coordinated movements of lower and upper limbs, characterized by a focal component (the hand must reach a target) and a postural component (the center of mass must remain inside the support base). The model is based on an extension of the equilibrium point hypothesis that has been called Passive Motion Paradigm (PMP), modified in order to achieve terminal attractor features and allow the integration of multiple constraints. The model is a network with terminal attractor dynamics. By simulating it in various conditions it was possible to show that it exhibits many of the spatio-temporal features found in experimental data. In particular, the motion of the center of mass appears to be synchronized with the motion of the hand and with proportional amplitude. Moreover, the joint rotation patterns can be accounted for by a single functional degree of freedom, as shown by principal component analysis. It is also suggested that recent findings in motor imagery support the idea that the PMP network may represent the motor cognitive part of synergy formation, uncontaminated by the effect of execution.