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Experimental Methods to Study Human Postural Control
Published on: September 11, 2019
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Identification of the Unstable Human Postural Control System
Sungjae Hwang1, Peter Agada2, Tim Kiemel2
1Department of Kinesiology, Temple University Philadelphia, PA, USA.
Frontiers in Systems Neuroscience
|March 26, 2016
Summary
Human balance control adapts to different surfaces, but the exact control strategy changes are unclear. New methods show postural changes stem from altered body mechanics, not just strategy shifts, aiding balance disorder treatments.
Area of Science:
- Biomechanics
- Neuroscience
- Systems Biology
Background:
- Maintaining upright bipedal posture necessitates adaptive control systems for varying environmental conditions, like different support surfaces.
- Observed behavioral shifts (e.g., ankle vs. hip strategy) on different surfaces are often attributed to altered control strategies, but pinpointing these changes within the control loop is difficult.
Purpose of the Study:
- To identify musculoskeletal and neural feedback components of the human postural control loop using the joint input-output (JIO) method.
- To determine how control loop changes correspond to behavioral adaptations on different support surfaces.
Main Methods:
- Employed the joint input-output (JIO) method for closed-loop system identification.
- Subjects experienced simultaneous mechanical and sensory perturbations while standing on normal and short support surfaces.
Main Results:
- A significant phase reversal occurred between visual input and body kinematics when changing support surfaces.
- This phase reversal shifted from trunk-leading-legs to legs-leading-trunk with increasing visual perturbation frequency.
- Decomposition revealed that behavioral changes on different surfaces are linked to alterations in the 'plant' (body dynamics), not necessarily a revised control strategy.
Conclusions:
- The joint input-output (JIO) method effectively identifies contributions of specific components within closed-loop systems to postural behavior.
- Observed postural adaptations to different support surfaces are primarily due to changes in the physical properties of the body (the plant), rather than a fundamental shift in the neural control strategy.
- This approach offers potential for improving treatments for balance disorders.
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