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August 17, 2009

Announcements

  • Move the meeting to Friday at 2:15p?
  • Some new faces: Joey, Shalv, and Sharon.
  • Seminars: Phys - wed@12p; Emory Spinal Chord - wed@8:30a; Robotics - ???
  • Stroke papers: Reisman and Scholz 2003, Dewald 2001, Dewald 1995

Presentation

by Keith van Antwerp
Todorov, Jordan. 2002. Optimal Control as a Theory for Motor Coordination.  Nature Neuroscience.
  • Lots of degrees of freedom in the biological system
  • Biological systems are capable of reliably achieving high-level goals
    • Variability occurs on the uncontrolled manifold
  • Enforcing end-point trajectories often removes the variability observed in biology
  • Stochastic Optimal Control explains this better
    • Assumptions
      • Actuator noise increases with magnitude of signal
      • An internal forward model exists
      • The sensors have noise and the feedback is delayed
      • The system has a method of penalizing effort
  • The uncertainty of the system is projected onto the redundant degrees-of-freedom
    • Coupling of the control signals helps counter-act addition of "noise"

Paper discussion

  • Do muscle synergies produce task-level functions, or are they an artifact of a sophisticated analysis?
  • Are muscle synergies innate or learned?
  • How many muscle synergies are required for task performance?
  • Theory of sparse coding and how it applies to neuromechanics.
  • Variability of nervous and mechanics.
  • Optimal control
  • Pathologies
  • Sensory information.
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