Human motor skills are remarkably complex because they require coordinating many muscles acting on many joints. A widely held, but controversial, hypothesis in neuroscience is that the nervous system simplifies learning and control using a modular architecture, based on modules called synergies. Previous evidence for modularity had been indirect, based on statistical regularities in the motor commands. In contrast, we designed a novel approach based virtual surgeries, and simulated surgical rearrangements of the tendons of human subjects that contributed to force generation in the hand. We tested the prediction that in a truly modular controller it must be harder to adapt to surgeries that are incompatible with the synergies. Our results provide direct evidence that muscle synergies are key elements of a modular architecture underlying motor control and adaptation.
This work was funded by a collaborative international Human Frontier Science Program grant, to Andrea d’Avella (Italy) and Dinesh K. Pai (Canada).
- D. Berger, R. Gentner, T. Edmunds, D. K. Pai, A. d’Avella, “Differences in adaptation rates after virtual surgeries provide direct evidence for modularity,” J. Neuroscience, 33(30), July 2013, pp. 12384-12394. [DOI]
- A. d’Avella and D. K. Pai, “Modularity for Sensorimotor Control: Evidence and a New Prediction,” in J. Motor Behavior, 42: 6, November 2010. pp. 361-369. [DOI]
Additional details and elaborations:
- D. Borzelli, D. J. Berger, D. K. Pai, A. D’avella, “Effort minimization and synergistic muscle recruitment for three-dimensional force generation, “Frontiers in Computational Neuroscience, 7:120. December 2013. [DOI]
- R. Gentner, T. Edmunds, D. K. Pai, A. d’Avella, “Robustness of muscle synergies during visuomotor adaptation,” Frontiers in Computational Neuroscience, 7:120. September 2013. 12 pages. [DOI]
- D. Borzelli, R. Gentner, T. Edmunds, D. K. Pai, A. d’Avella, “Directional tuning of arm muscle activation in isometric force generation and its prediction by flexible and synergistic models.” Proceedings of 4th IEEE RAS & EMBS International Conference on Biomedical Robotics and Biomechatronics (BioRob), 2012. pp 1241-1246. [DOI]
- T. Edmunds, R. Gentner, A. d’Avella, and D. K. Pai, “Feasible Wrench Space and its Estimation for Isometric Haptic Interaction,” in Proceedings of the IEEE Haptics Symposium, Vancouver, BC, March 4-7, 2012. pp.323-327. [DOI]