Neuro-mechanical model for limb movement control
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1
Pazmany Peter Catholic University, Faculty of Information Technology, Hungary
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2
New York University Medical center, Department of Physiology and Neuroscience, United States
We proposed a concept of a general multilevel model to control limb movements and to mimic muscle activities and joint rotations as a function of spinal motoneuron pool discharge rate. The modeled relationship between neural signals, muscle forces and joint rotations, considers how motoneuron pool stimulation patterns and biomechanical characteristics of the musculoskeletal system affect kinematic movement patterns. We consider geometric and inertial properties of limb segments, muscle attachment sites, muscle force-length, force-frequency, force-velocity relationships, and a load parameter that simulates body weight. The issue is to compute underlying motoneuron firing activities based on given experimentally observed angular changes in limb posture. There are a large number of solutions for the generation of a given joint rotation with muscle activation. This is known as an overcompletness problem and we approach it proposing that each joint is controlled by a pair of muscle groups (one flexor and one extensor) and that only 1 of the 2 groups is activated at a given time. Using this assumption we developed an inverse model to provide firing frequencies of flexor and extensor motoneuron pools that would generate the given angular change in each joint. We applied the model to swimming and walking rats. We studied the sensitivity of the model to limb posture examining how motoneuron activity patterns would change if joints would be more flexed or extended during the execution of a motor task. In the more extended case, lower activation frequencies for the muscles were computed while the opposite was the case when the joints were more flexed. This may be explained by biomechanical laws and by motor control principles. Posture may be optimized for more extended locomotion patterns, requiring lower motoneuron pool discharge rates. The model can be applied to provide stimulation patterns for functional electrical stimulation in human locomotion as cycling or walking.
Conference:
IBRO International Workshop 2010, Pécs, Hungary, 21 Jan - 23 Jan, 2010.
Presentation Type:
Poster Presentation
Topic:
Sensory and motor systems
Citation:
Laczkó
J,
Walton
K and
Llinas
R
(2010). Neuro-mechanical model for limb movement control.
Front. Neurosci.
Conference Abstract:
IBRO International Workshop 2010.
doi: 10.3389/conf.fnins.2010.10.00242
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Received:
05 May 2010;
Published Online:
05 May 2010.
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Correspondence:
József Laczkó, Pazmany Peter Catholic University, Faculty of Information Technology, Budapest, Hungary, laczko@itk.ppke.hu