Linearity, motor primitives and low-dimensionality in the spinal organization of motor control

The typical biological system is nonlinear, high-dimensional and highly redundant, all of which are burdens on controller design. Yet despite these complications, the central nervous system is able to control motor systems with an impressive level of complexity and effectivity. One such example is the frog. Evidence suggests that in frogs, the central nervous system, and the spinal cord in particular, may adopt simplifying strategies to ease the motor control problem. For instance, despite the known nonlinear nature of muscle, it has been demonstrated experimentally that spinally induced force production in the frog limb is linear in stimulation. Spinally encoded force fields have also been implicated as building blocks for generating hind limb movements. Furthermore, muscle EMG measurements for both intact and spinalized animals, have been shown to be low-dimensional; these measurements can be reconstructed as linear combinations of fixed muscle activations, or synergies. The evidence above suggests that the central nervous system may adopt simplifying strategies for the motor control problem. First, the thesis addresses the issue of linearity in isometric force fields. It proposes that this behavior can be explained as a result of biomechanical properties. To this end, a physiologically realistic model of the frog hind limb is analyzed.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Mechanical Engineering

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Berniker, Max (Max Sam), 1971-

Advisor dc:contributor.advisor

• Emilio Bizzi.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/33919

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/33919