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The filtering of the posturographic signals shows the age related features.

Michalak KP, Przekoracka-Krawczyk A, Nawrot P, Woźniak P, Vieregge P - ScientificWorldJournal (2014)

Bottom Line: The statistically significant differences in the mutual dependence between x and y components between the groups of patients were analyzed using MANOVA.The significant differences were observed mainly in the range of filter frequencies f = 0.1-1.5 Hz and f = 2.2-5.5 Hz with a maximum effect at approximately 4-5 Hz.A detailed post-hoc analysis is also presented.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Vision Science and Optometry, Faculty of Physics, Adam Mickiewicz University of Poznań, Umultowska Street 85, 61-614 Poznań, Poland.

ABSTRACT

Objective: Lower frequencies of slow oscillations of the posturographic signals can be removed using high-pass filtering. This procedure releases postural reflexes possessing higher frequencies and lower amplitude range. Mutual dependence between the x and y components of posturographic signals was analyzed using principal component analysis (PCA). The posturographic signals of old patients with idiopathic gait disturbance were compared with the control group of similar age and with younger patients. There was also the analysis of the influence of the eyes state (open versus closed) and the head position (normal or bent back). The statistically significant differences in the mutual dependence between x and y components between the groups of patients were analyzed using MANOVA. The significant differences were observed mainly in the range of filter frequencies f = 0.1-1.5 Hz and f = 2.2-5.5 Hz with a maximum effect at approximately 4-5 Hz. A detailed post-hoc analysis is also presented. The differences in the higher frequency range suggest the main disturbance to be connected with the spinal reflexes. Visual and vestibular support appear insufficient for postural stability control in the idiopathic gait disturbance group. The results suggest that idiopathic gait disturbance is the final stage of the aging process of postural system.

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Related in: MedlinePlus

Example of the posturographic signal after 2.6 Hz high-pass filtering. The low frequency and large-amplitude oscillations are removed uncovering the relation between xn and yn components. After the PCA rotation, the first column S1 represents the long diagonal of the path area and the second column (S2) represents the short diagonal.
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fig1: Example of the posturographic signal after 2.6 Hz high-pass filtering. The low frequency and large-amplitude oscillations are removed uncovering the relation between xn and yn components. After the PCA rotation, the first column S1 represents the long diagonal of the path area and the second column (S2) represents the short diagonal.

Mentions: Figure 1 shows the example of the high-pass filtered posturographic signal using filter frequency f = 2.6 Hz in which high relation between xn and yn is observed. xn and yn components are visible to be dependent each to other. This figure shows also the necessity of the preliminary normalization of the components. If one of the components xn/yn would be stronger than the second one, the ratio between SII and SI in PCA method would refer mainly to the ratio between them and not to their common dependence.


The filtering of the posturographic signals shows the age related features.

Michalak KP, Przekoracka-Krawczyk A, Nawrot P, Woźniak P, Vieregge P - ScientificWorldJournal (2014)

Example of the posturographic signal after 2.6 Hz high-pass filtering. The low frequency and large-amplitude oscillations are removed uncovering the relation between xn and yn components. After the PCA rotation, the first column S1 represents the long diagonal of the path area and the second column (S2) represents the short diagonal.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4281402&req=5

fig1: Example of the posturographic signal after 2.6 Hz high-pass filtering. The low frequency and large-amplitude oscillations are removed uncovering the relation between xn and yn components. After the PCA rotation, the first column S1 represents the long diagonal of the path area and the second column (S2) represents the short diagonal.
Mentions: Figure 1 shows the example of the high-pass filtered posturographic signal using filter frequency f = 2.6 Hz in which high relation between xn and yn is observed. xn and yn components are visible to be dependent each to other. This figure shows also the necessity of the preliminary normalization of the components. If one of the components xn/yn would be stronger than the second one, the ratio between SII and SI in PCA method would refer mainly to the ratio between them and not to their common dependence.

Bottom Line: The statistically significant differences in the mutual dependence between x and y components between the groups of patients were analyzed using MANOVA.The significant differences were observed mainly in the range of filter frequencies f = 0.1-1.5 Hz and f = 2.2-5.5 Hz with a maximum effect at approximately 4-5 Hz.A detailed post-hoc analysis is also presented.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Vision Science and Optometry, Faculty of Physics, Adam Mickiewicz University of Poznań, Umultowska Street 85, 61-614 Poznań, Poland.

ABSTRACT

Objective: Lower frequencies of slow oscillations of the posturographic signals can be removed using high-pass filtering. This procedure releases postural reflexes possessing higher frequencies and lower amplitude range. Mutual dependence between the x and y components of posturographic signals was analyzed using principal component analysis (PCA). The posturographic signals of old patients with idiopathic gait disturbance were compared with the control group of similar age and with younger patients. There was also the analysis of the influence of the eyes state (open versus closed) and the head position (normal or bent back). The statistically significant differences in the mutual dependence between x and y components between the groups of patients were analyzed using MANOVA. The significant differences were observed mainly in the range of filter frequencies f = 0.1-1.5 Hz and f = 2.2-5.5 Hz with a maximum effect at approximately 4-5 Hz. A detailed post-hoc analysis is also presented. The differences in the higher frequency range suggest the main disturbance to be connected with the spinal reflexes. Visual and vestibular support appear insufficient for postural stability control in the idiopathic gait disturbance group. The results suggest that idiopathic gait disturbance is the final stage of the aging process of postural system.

Show MeSH
Related in: MedlinePlus