Considerations on the application of the chaos paradigm to describe the postural sway

Pascolo, P.; Barazza, Fausto; Carniel, Roberto

doi:10.1016/j.chaos.2005.04.111

Cited by 22 publications

(17 citation statements)

References 16 publications

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“…In [18,19] it was demonstrated that the postural act is indeed chaotic although it was difficult to discriminate between control and Parkinsonian subjects. In fact the difficulty in estimating nonlinear parameters, i.e., LLE and dimension of correlation, did not help to clarify the chaoticity of the system.…”

Section: Introductionmentioning

confidence: 97%

Nonlinear analysis of posturographic data

Ladislao

Fioretti

2007

Med Bio Eng Comput

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The aim of this work is to determine whether postural sway can be well described by nonlinear deterministic modelling. Since the results of nonlinear analysis depend on experimental data processing, emphasis was given to the assessment of a proper methodology to process posturographic data. Centre of Pressure (CoP) anterior-posterior (AP) displacements (stabilogram) were obtained by static posturography tests performed on control subjects. A nonlinear determinism test was applied to investigate the nature of data. A nonlinear filtering method allowed us to estimate properly the parameters of the nonlinear model without altering signal dynamics. The largest Lyapunov exponent (LLE) was estimated to quantify the chaotic behaviour of postural sway. LLE values were found to be positive although close to zero. This suggests that postural sway derives from a process exhibiting weakly chaotic dynamics.

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Section: Introductionmentioning

confidence: 97%

Nonlinear analysis of posturographic data

Ladislao

Fioretti

2007

Med Bio Eng Comput

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“…The LLE results were all positive but with near-zero values which implied a weakly-chaotic nature for the body reactions to the rotational perturbations. Such a behavior was identified for the quiet standing when the parameter of nonlinear analysis was the CoP (Ladislao and Fioretti 2007, Lamoth and van Heuvelen 2012, Pascolo et al 2006, Yamada 1995. Application of nonlinear dynamics on the CoM displacement in perturbed stance also showed weak chaotic responses of the body in different physical and sensory conditions.…”

Section: Nonlinear Dynamicsmentioning

confidence: 97%

“…Obviously, the stance in the perturbed cases requires more neural and muscular efforts compared with quiet standing (Creath et al 2005). The later, however, has been subjected to a wide range of nonlinear analyses from assuring its chaotic nature (Buzzi et al 2003, Collins et al 1995, Hausdorff et al 2001, Yamada 1995 to developing a discriminative metric for the sensory interference (Ladislao andFioretti 2007, Negahban et al 2013), muscular frailty or aging (Blaszczyk andKlonowski 2001, Han et al 2005), locomotive diseases (Pascolo et al 2006), and also in environmental changes (Murata andIwase 1998, Negahban et al 2013).…”

Section: Introductionmentioning

confidence: 99%

“…The LLE assesses the convergence or divergence of a time series trajectory relative to a reference one. Many researchers (Ladislao and Fioretti 2007, Murata and Iwase 1998, Pascolo et al 2006, Safi et al 2015, Yamada 1995 found the LLE positive or slightly above zero and concluded that the postural sway is chaotic and the better standing conditions e.g. youth, health, open eyes, fixed support, etc.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Nonlinear dynamics analysis of the human balance control subjected to physical and sensory perturbations

Ashtiani¹,

Azghani²

2017

Acta Neurobiologiae Experimentalis

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Postural control after applying perturbation involves neural and muscular efforts to limit the center of mass (CoM) motion. Linear dynamical approaches may not unveil all complexities of body efforts. This study was aimed at determining two nonlinear dynamics parameters (fractal dimension (FD) and largest Lyapunov exponent (LLE)) in addition to the linear standing metrics of balance in perturbed stance. Sixteen healthy young males were subjected to sudden rotations of the standing platform. The vision and cognition during the standing were also interfered. Motion capturing was used to measure the lower limb joints and the CoM displacements. TheCoM path length as a linear parameter was increased by elimination of vision (p<0.01) and adding a cognitive load (p<0.01). The CoM nonlinear metric FD was decreased due to the cognitive loads (p<0.001). The visual interference increased the FD of all joints when the task included the cognitive loads (p<0.01). The slightly positive LLE values showed weakly-chaotic behavior of the whole body. The local joint rotations indicated higher LLEs. Results indicated weakly chaotic response of the whole body. Increase in the task difficulty by adding sensory interference had difference effects on parameters. Linear and nonlinear metrics of the perturbed stance showed that a combination of them may properly represent the body behavior.

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“…The lag times of the muscular activation and the internal respiration are also considered (Pascolo et al, 2003;. Finally, Pascolo et al ( , 2005 discussed the implications of nonlinearities and the possible presence of chaos in the postural sway.…”

Section: Article In Pressmentioning

confidence: 98%