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Contribution of stretch reflexes to locomotor control: a modeling study
S Yakovenko1, V Gritsenko, A Prochazka
1Centre for Neuroscience, University of Alberta 513 HMRC, Edmonton, Alberta T6G 2S2, Canada.
Biological Cybernetics
|March 5, 2004
Summary
Muscle properties offer automatic load compensation, but sensory control is crucial, especially at low central activity levels. Finite-state control significantly enhances locomotor system adaptability.
Area of Science:
- Biomechanics
- Neuroscience
- Robotics
Background:
- Muscle properties provide inherent load compensation during locomotion.
- The precise role of sensory feedback in motor control remains a key question.
Purpose of the Study:
- To investigate the significance of sensory control versus intrinsic muscle properties in load compensation.
- To test hypotheses regarding the contribution of stretch reflexes and state-dependent sensory processing.
Main Methods:
- A 9-segment, 2-legged planar locomotor model with 12 musculotendon actuators was developed.
- Simulated stretch reflexes (Ia afferents) and tendon organ feedback (Ib afferents) with 35 ms latency were incorporated.
- Locomotor stability was assessed via open-loop (deafferented) and closed-loop (sensory feedback, finite-state rules) simulations.
Main Results:
- Intrinsic muscle stiffness alone can yield stable gait patterns without sensory input.
- Stretch reflexes become critical for load compensation when central neural drive is low.
- Finite-state control significantly expands the locomotor system's adaptive capacity.
Conclusions:
- Intrinsic limb mechanics contribute substantially to stable locomotion.
- Sensory feedback, particularly stretch reflexes, plays a vital, context-dependent role in load compensation.
- Advanced control strategies like finite-state rules offer superior adaptability.