Mechanical analysis and hierarchies of multidigit synergies during accurate object rotation

Wei Zhang, Halla B. Olafsdottir, Vladimir M. Zatsiorsky, Mark L. Latash

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

We studied the mechanical variables (the grip force and the total moment of force) and multidigit synergies at two levels (the virtual finger-thumb level, VF-TH, and the individual finger level, IMRL) of a hypothetical control hierarchy during accurate rotation of a hand-held instrumented handle. Synergies were defined as covaried changes in elemental variables (forces and moments of force) that stabilize the output at a particular level. Indices of multidigit synergies showed higher values at the hierarchically higher level (VF-TH) for both normal and tangential forces. The moment of force was stabilized at both hierarchical levels during the steady-state phases but not during the movement. The results support the principles of superposition and of mechanical advantage. They also support an earlier hypothesis on an inherent trade-off between synergies at the two hierarchical levels, although the controller showed more subtle and versatile synergic control than the one hypothesized earlier.

Original languageEnglish (US)
Pages (from-to)251-279
Number of pages29
JournalMotor control
Volume13
Issue number3
DOIs
StatePublished - Jul 2009

All Science Journal Classification (ASJC) codes

  • Physical Therapy, Sports Therapy and Rehabilitation
  • Clinical Neurology
  • Physiology (medical)

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