Abstract
Trunk stabilization is required to control posture and movement during daily activities. Various sensory modalities, such as muscle spindles, Golgi tendon organs and the vestibular system, might contribute to trunk stabilization and our aim was to assess the contribution of these modalities to trunk stabilization. In 35 healthy subjects, upper-body sway was evoked by continuous unpredictable, force-controlled perturbations to the trunk in the anterior direction. Subjects were instructed to either 'maximally resist the perturbation' or to 'relax but remain upright' with eyes closed. Frequency response functions (FRFs) of admittance, the amount of movement per unit of force applied, and reflexes, the modulation of trunk extensor activity per unit of trunk displacement, were obtained. To these FRFs, we fitted physiological models, to estimate intrinsic trunk stiffness and damping, as well as feedback gains and delays. The different model versions were compared to assess which feedback loops contribute to trunk stabilization. Intrinsic stiffness and damping and muscle spindle (short-delay) feedback alone were sufficient to accurately describe trunk stabilization, but only with unrealistically low reflex delays. Addition of muscle spindle acceleration feedback or inhibitory Golgi tendon organ feedback yielded realistic delays and improved the model fit, with a significantly better model fit with acceleration feedback. Addition of vestibular feedback did not improve the model fit. In conclusion, muscle spindle feedback and intrinsic mechanical properties are sufficient to describe trunk stabilization in the sagittal plane under small mechanical perturbations, provided that muscle spindles encode acceleration in addition to velocity and position information.
Original language | English |
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Pages (from-to) | 219-227 |
Number of pages | 9 |
Journal | Journal of Biomechanics |
Volume | 70 |
Early online date | 5 Aug 2017 |
DOIs | |
Publication status | Published - 21 Mar 2018 |
Funding
The authors would like to thank Mariette Griffioen, Jeffrey Warmerdam and Drs. Erwin Maaswinkel and Matej Voglar for help in data collection and Dr. Huub Maas for reviewing a draft version of this paper. The study was partially supported by the Dutch Technology Foundation STW , which is part of the Netherlands Organization for Scientific Research (NWO), and which is partly funded by the Ministry of Economic Affairs . See www.neurosipe.nl – Project 10732: QDISC. The authors would like to thank Mariette Griffioen, Jeffrey Warmerdam and Drs. Erwin Maaswinkel and Matej Voglar for help in data collection and Dr. Huub Maas for reviewing a draft version of this paper. The study was partially supported by the Dutch Technology Foundation STW, which is part of the Netherlands Organization for Scientific Research (NWO), and which is partly funded by the Ministry of Economic Affairs. See www.neurosipe.nl ? Project 10732: QDISC.
Funders | Funder number |
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Netherlands Organization for Scientific Research | |
Ministerie van Economische Zaken | 10732 |
Nederlandse Organisatie voor Wetenschappelijk Onderzoek | |
Stichting voor de Technische Wetenschappen |
Keywords
- Feedback
- Postural control
- Spine
- System identification