Time-varying characteristics of visually induced postural sway

Loughlin, Patrick J.; Redfern, Mark S.; Furman, Joseph M.

doi:10.1109/86.547944

Cited by 48 publications

(29 citation statements)

References 24 publications

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“…For the 0.3 Hz scene movement, COP power was calculated within the 0.25-0.35 Hz frequency band. This technique measures sway in response to the scene movement (entrainment) and not generalized destabilization (Redfern & Furman, 1994;Loughlin & Redfern, 1996).…”

Section: Data Processing and Statistical Analysesmentioning

confidence: 99%

Visually induced postural sway in anxiety disorders

Redfern

Furman

Jacob

2007

Journal of Anxiety Disorders

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Postural sensitivity to moving visual environments in patients with anxiety disorders was studied. We hypothesized that patients with anxiety disorders would have greater sway in response to a moving visual environment compared to healthy adults, especially if they have space and motion discomfort (SMD). Twenty one patients with generalized anxiety without panic (NPA), and 38 patients with panic and agoraphobia (PAG) were compared to 22 healthy controls. SMD was evaluated in all subjects via questionnaire. Subjects stood on a force platform that was either fixed or rotating with the subject (i.e. sway referenced) during exposure to a sinusoidally moving visual surround. Center of Pressure (COP) data were computed from force transducers in the platform as a measure of sway. Results showed that patients swayed significantly more in response to the moving visual scene compared to control subjects, with no differences between the NPA and PAG groups. SMD was a predictor of sway response in the patients: patients with high SMD swayed significantly more than both Controls and anxiety patients with low SMD. These results indicate that patients with anxiety disorders, particularly those with SMD, are more visually dependent for balance. This subgroup of patients may be amenable to treatment used for patients with balance disorders (i.e. vestibular rehabilitation) that focuses on sensory re-integration processes that address visual sensitivity.

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Section: Data Processing and Statistical Analysesmentioning

confidence: 99%

Visually induced postural sway in anxiety disorders

Redfern

Furman

Jacob

2007

Journal of Anxiety Disorders

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“…Med., 2008, 216 (3), 277-285. © 2008 Visual perception is closely related to postural control and provides afferent feedback regarding postural sway to the cerebellum (Loughlin et al 1996;Loughlin and Redfern, 2001). Visual function is mainly evaluated via visual acuity and the visual fields (Margolis et al 2002).…”

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confidence: 99%

Low Visual Acuity is Associated with the Decrease in Postural Sway

Uchiyama

Demura

2008

Tohoku J. Exp. Med.

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Vision contributes to upright postural control by providing afferent feedback to the cerebellum. Vision is generally classified into central and peripheral vision, but little is known about the respective role of central and peripheral vision for postural control with different visual acuity levels. This study examined the influence of visual acuity and visual field conditions on upright posture. Eleven males (21.1 ± 2.0 yrs) and 15 females (22.2 ± 2.2 yrs) were classified into high (above 1.0 binocular vision) and low (below 0.3) visual acuity groups. Postural sway was measured for 1 min in each of three visual field conditions (central vision, full vision, and no vision). Participants were given only central visual information (central vision), central and peripheral visual information (full vision), or no visual information (no vision). The effect of central vision on postural sway was detected as a difference between no vision and central vision conditions, and the effect of peripheral vision was assessed as a difference between central vision and full vision conditions. The low visual acuity group decreased their sway amplitude in antero-posterior direction using central plus peripheral visual information, but the high visual-acuity group did not. The high frequency sway was significantly smaller in the low visual-acuity group than that in the high visual-acuity group under the no vision and central vision conditions. These findings suggest the necessity of considering participants' visual acuity in examining the role of the visual information from the central and peripheral visual fields. postural control; visual acuity; upright stance; center of pressure; healthy young adults.Tohoku

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“…We have demonstrated that a time domain statistical model provides a more sensitive measure of postural organization than the more commonly used measure of center of pressure (Jonsson et al 2004(Jonsson et al , 2005Barbier et al 2003;Colobert et al 2006;Betker et al 2006) which is a global outcome measure and does not fully describe segmental postural behaviors. A perturbed postural system does not necessarily respond only at the driving frequency (Creath et al 2005;Loughlin et al 1996;Loughlin and Redfern 2001) and one of the advantages of this statistical model is that it is not limited to describing behavior just at the driving frequency. We believe that this model will enable us to explore the full bandwidth of adaptive postural control during complex tasks.…”

Section: Discussionmentioning

confidence: 99%

“…Previous studies have shown that sway during quiet stance (Carroll and Freedman 1993;Collins and De Luca 1993;Schumann et al 1995;Loughlin et al 1996;Creath et al 2005;Guelton et al 2008) exhibits non-linear and timevarying behavior suggesting shifting mechanisms for control. Furthermore, Creath et al (2005) have proposed that the whole body behaves like a multi-link pendulum during quiet stance and has two simultaneously co-existing excitable modes.…”

Section: Introductionmentioning

confidence: 99%

Examination of time-varying kinematic responses to support surface disturbances

Gürses¹,

Kenyon²,

Keshner³

2011

Biomedical Signal Processing and Control

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Abstract:To examine the evolution of inter-segmental coordination over time, a previously developed multi-variate model of postural coordination during quiet stance (Kuo et al. 1998) has been extended. In the original model, postural coordination was treated as an eigenvalue-eigenvector problem between two segmental degrees of freedom represented by angular displacements of the trunk and lower limb. Strategies of postural coordination were then identified using the sign of the covariance between the two segments' angular displacements. In contrast to the original model, the current model first subdivided the entire trial into smaller time segments, comprising four cycles of perturbation, i.e., a 16 sec window. This window marched along the data advancing in 8.3 ms steps, each time performing the computation from the original model on the terms of the covariance matrix. The resulting time-segment-dependent postural strategies estimated the changes in posture control that took place over the course of the experiment. In addition to the statistical modeling, the auto-power spectrums and cross-spectral density function estimates for the entire trial, as well as for the individual time-segments, were analyzed. In these experiments subjects experienced a 0.25 Hz sinusoidal perturbation of a platform while exposed to a virtual reality environment. The data we collected showed that the statistical and spectral characteristics across the entire trial may differ from individual time segments of the same trial indicating time varying postural behavior. Comparison of these results from young and elderly subjects revealed that the time dependency observed in postural behavior was sensitive to aging. The young population managed to be consistent in their postural behavior throughout the entire trial and responded to the perturbation frequency with an out-of-phase response between the postural segments. Elderly subjects, however, demonstrated inconsistent postural behaviors as they switched back and forth between different postural coordination patterns within a trial.

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Time-varying characteristics of visually induced postural sway

Cited by 48 publications

References 24 publications

Visually induced postural sway in anxiety disorders

Visually induced postural sway in anxiety disorders

Low Visual Acuity is Associated with the Decrease in Postural Sway

Examination of time-varying kinematic responses to support surface disturbances

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