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.