Central and sensory contributions to the activation and organization of muscle synergies during natural motor behaviors

Vincent C K Cheung, Andrea D'Avella, Matthew C. Tresch, Emilio Bizzi

Research output: Contribution to journalArticlepeer-review

Abstract

Previous studies have suggested that the motor system may simplify control by combining a small number of muscle synergies represented as activation profiles across a set of muscles. The role of sensory feedback in the activation and organization of synergies has remained an open question. Here, we assess to what extent the motor system relies on centrally organized synergies activated by spinal and/or supraspinal commands to generate motor outputs by analyzing electromyographic (EMG) signals collected from 13 hindlimb muscles of the bullfrog during swimming and jumping, before and after deafferentation. We first established that, for both behaviors, the intact and deafferented data sets possess low and similar dimensionalities. Subsequently, we used a novel reformulation of the non-negative matrix factorization algorithm to simultaneously search for synergies shared by, and synergies specific to, the intact and deafferented data sets. Most muscle synergies were identified as shared synergies, suggesting that EMGs of locomotor behaviors are generated primarily by centrally organized synergies. Both the amplitude and temporal patterns of the activation coefficients of most shared synergies, however, were altered by deafferentation, suggesting that sensory inflow modulates activation of those centrally organized synergies. For most synergies, effects of deafferentation on the activation coefficients were not consistent across frogs, indicating substantial interanimal variability of feedback actions. We speculate that sensory feedback might adapt recruitment of muscle synergies to behavioral constraints, and the few synergies specific to the intact or deafferented states might represent afferent-specific modules or feedback reorganization of spinal neuronal networks.

Original languageEnglish
Pages (from-to)6419-6434
Number of pages16
JournalJournal of Neuroscience
Volume25
Issue number27
DOIs
Publication statusPublished - Jul 6 2005

Keywords

  • Afferent
  • Central pattern generators
  • Deafferentation
  • Feedback
  • Frog
  • Jumping
  • Locomotion
  • Non-negative matrix factorization
  • Swimming

ASJC Scopus subject areas

  • Neuroscience(all)

Fingerprint Dive into the research topics of 'Central and sensory contributions to the activation and organization of muscle synergies during natural motor behaviors'. Together they form a unique fingerprint.

Cite this