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Force and Position Control in Humans - The Role of Augmented Feedback
Published on: June 19, 2016
Long-latency muscle activity reflects continuous, delayed sensorimotor feedback of task-level and not joint-level
Seyed A Safavynia1, Lena H Ting
1Neuroscience Program, Emory University, Atlanta, Georgia;
Journal of Neurophysiology
|June 28, 2013
Summary
Long-latency muscle responses rely on task-level error feedback, not joint-level errors. This suggests a common sensorimotor control mechanism for limb movements across the body.
Area of Science:
- Neuroscience
- Biomechanics
- Motor Control
Background:
- Electromyographic (EMG) responses show distinct short- and long-latency modulation patterns.
- Long-latency responses are thought to be goal-directed, related to task achievement.
- Previous work identified an error-based sensorimotor feedback transformation for balance.
Purpose of the Study:
- To test the robustness of a sensorimotor transformation under varied perturbation conditions and postural states.
- To determine if sensorimotor transformation relies on task-level or joint-level error feedback.
- To investigate the continuous modulation of long-latency responses by task-level error.
Main Methods:
- Developed novel acceleration pulse perturbation trains for dynamic balance tasks.
- Applied perturbations during recovery from preceding disturbances to create complex postural states.
- Reconstructed electromyographic (EMG) responses using center of mass (CoM) kinematics at long latencies.
- Compared reconstruction accuracy using CoM versus joint kinematics.
Main Results:
- EMG responses were accurately reconstructed using CoM kinematics at long delays (∼100 ms).
- CoM and joint kinematics decorrelated during perturbation trains, enabling direct comparison of feedback types.
- Reconstruction using joint kinematics was significantly poorer and required unphysiologically short delays (∼10 ms).
Conclusions:
- Continuous, long-latency feedback of task-level variables likely regulates long-latency responses.
- This task-level error feedback mechanism may be common across upper and lower limb movements.
- Findings support a unified sensorimotor control strategy for goal-directed limb actions.
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