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Postural control and adaptation to threats to balance stability

Patel, Mitesh LU (2009) In Lund University, Faculty of Medicine Doctoral Dissertation Series 2009:47.
Abstract
Postural control is the ability to maintain equilibrium and orientation in a gravitational environment. It is dependent on feedback and feedforward mechanisms that generate appropriate corrective movement based on body-sway motion detected primarily by visual, vestibular, and proprioceptive sensory systems. Since information from the various senses is not always accurate (e.g. by disease) or available (e.g. with eyes closed), the postural control system must adapt to maintain stance. This thesis aimed to investigate postural control and adaptation to threats of balance.

Effective approaches for the clinical measurement of postural control still remains to be developed. In the past, it has been common to investigate patients’... (More)
Postural control is the ability to maintain equilibrium and orientation in a gravitational environment. It is dependent on feedback and feedforward mechanisms that generate appropriate corrective movement based on body-sway motion detected primarily by visual, vestibular, and proprioceptive sensory systems. Since information from the various senses is not always accurate (e.g. by disease) or available (e.g. with eyes closed), the postural control system must adapt to maintain stance. This thesis aimed to investigate postural control and adaptation to threats of balance.

Effective approaches for the clinical measurement of postural control still remains to be developed. In the past, it has been common to investigate patients’ balance by having them stand upon compliant foam blocks with eyes open and closed since standing on foam is believed to affect the accuracy of information from cutaneous mechanoreceptors on the soles of the feet. However, when assessing balance on foam blocks with different compliances and mechanical properties, it was found that postural sway was larger on firmer compliant surfaces, which also increased the importance of visual information.

Postural adaptation was also investigated by repeatedly perturbing balance using muscle vibrations. In healthy, young persons, a slow adaptive change was observed. This adaptation involved decreased costs of standing including decreased energy, body movement and muscle activity and changes to the relationship between muscle activity and movement. The characteristics of the adaptation also depended on the availability of visual information. The elderly had poor postural control with and without being perturbed but were able to adapt to improve their poor balance. However, decreased mechanoreceptive sensation in the elderly prevented them from adapting their balance to the level of younger test subjects. Sleep deprivation decreased attention and alertness and resulted in decreased postural control and adaptation.

The findings in this thesis extend what is known about motor learning. The adaptive learning capability of the postural control system, and hence the accurate reconstruction of the kinematics and kinetics of movement, was dependant on ones own mechanoreceptive somatosensation and availability of visual information. Decreasing attention and alertness through sleep deprivation decreased adaptive capabilities, suggesting an important role for sleep in memory and consolidation of a new motor skill. (Less)
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author
supervisor
opponent
  • Prof Wuyts, Floris, Department of Otorhinolaryngology, University Hospital Antwerp, Belgium
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Postural control, Visual, Vestibular, Somatosensory, Proprioception, Posturography, Complaint surface, Ageing, Mechanoreceptive sensation, Sleep deprivation, Adaptation, Muscle activity
in
Lund University, Faculty of Medicine Doctoral Dissertation Series
volume
2009:47
pages
146 pages
publisher
Lund University: Faculty of Medicine
defense location
Belfragesalan (D15), BMC, Lund University
defense date
2009-05-16 09:00
ISSN
1652-8220
ISBN
978-91-86253-35-6
language
English
LU publication?
yes
id
e591a4d4-1ec1-40fa-bd7f-d0fdbb0cc083 (old id 1369259)
date added to LUP
2009-04-24 13:26:41
date last changed
2016-09-19 08:44:48
@phdthesis{e591a4d4-1ec1-40fa-bd7f-d0fdbb0cc083,
  abstract     = {Postural control is the ability to maintain equilibrium and orientation in a gravitational environment. It is dependent on feedback and feedforward mechanisms that generate appropriate corrective movement based on body-sway motion detected primarily by visual, vestibular, and proprioceptive sensory systems. Since information from the various senses is not always accurate (e.g. by disease) or available (e.g. with eyes closed), the postural control system must adapt to maintain stance. This thesis aimed to investigate postural control and adaptation to threats of balance.<br/><br>
Effective approaches for the clinical measurement of postural control still remains to be developed. In the past, it has been common to investigate patients’ balance by having them stand upon compliant foam blocks with eyes open and closed since standing on foam is believed to affect the accuracy of information from cutaneous mechanoreceptors on the soles of the feet. However, when assessing balance on foam blocks with different compliances and mechanical properties, it was found that postural sway was larger on firmer compliant surfaces, which also increased the importance of visual information.<br/><br>
Postural adaptation was also investigated by repeatedly perturbing balance using muscle vibrations. In healthy, young persons, a slow adaptive change was observed. This adaptation involved decreased costs of standing including decreased energy, body movement and muscle activity and changes to the relationship between muscle activity and movement. The characteristics of the adaptation also depended on the availability of visual information. The elderly had poor postural control with and without being perturbed but were able to adapt to improve their poor balance. However, decreased mechanoreceptive sensation in the elderly prevented them from adapting their balance to the level of younger test subjects. Sleep deprivation decreased attention and alertness and resulted in decreased postural control and adaptation. <br/><br>
The findings in this thesis extend what is known about motor learning. The adaptive learning capability of the postural control system, and hence the accurate reconstruction of the kinematics and kinetics of movement, was dependant on ones own mechanoreceptive somatosensation and availability of visual information. Decreasing attention and alertness through sleep deprivation decreased adaptive capabilities, suggesting an important role for sleep in memory and consolidation of a new motor skill.},
  author       = {Patel, Mitesh},
  isbn         = {978-91-86253-35-6},
  issn         = {1652-8220},
  keyword      = {Postural control,Visual,Vestibular,Somatosensory,Proprioception,Posturography,Complaint surface,Ageing,Mechanoreceptive sensation,Sleep deprivation,Adaptation,Muscle activity},
  language     = {eng},
  pages        = {146},
  publisher    = {Lund University: Faculty of Medicine},
  school       = {Lund University},
  series       = {Lund University, Faculty of Medicine Doctoral Dissertation Series},
  title        = {Postural control and adaptation to threats to balance stability},
  volume       = {2009:47},
  year         = {2009},
}