Added Value and Clinical Significance of NonlinearVariability Indices of Walking Stride Interval inNeurodegenerative Diseases / Frédéric Dierick  

Public ISBD Titre : Added Value and Clinical Significance of NonlinearVariability Indices of Walking Stride Interval inNeurodegenerative Diseases Type de document : document électronique Auteurs : Frédéric Dierick ; Charlotte Vandevoorde ; Frédéric Chantraine ; Olivier White ; Fabien Buisseret Année de publication : 2020 Note générale : Cet article est une prépublication. doi: https://doi.org/10.1101/2020.01.31.20019455 Langues : Anglais (eng) Résumé : Though self-paced walking is highly stereotyped, the stride interval fluctuates from one stride to the next around an average value with a measurable statistical variability. In clinical gait analysis, this variability is usually assessed with indices such the standard deviation or the coefficient of variation (CV). The aim of this study is to understand the added value that nonlinear indices of walking stride interval variability, such as Hurst exponent (H) and Minkowski fractal dimension (D), can provide in a clinical context and to suggest a clinical significance of these indices in the most common neurodegenerative diseases: Parkinson, Huntington, and amyotrophic lateral sclerosis. Although evidence have been accumulated that the stride interval organization at long range displays a more random, less autocorrelated, gait pattern in neurodegenerative diseases compared with young healthy individuals, it is today necessary to recompute CV, H, and D indices in a unified way and to take into account aging impact on these indices. In fact, computed nonlinear indices of variability are mainly dependent on stride interval time series length and algorithms used, making quantitative comparisons between different studies difficult or even impossible. Here, we recompute these indices from available stride interval time series, either coming from our lab or from online databases, or made available to us by the authors of previously conducted research. We confirm that both linear and nonlinear variability indices are relevant indicators of aging process and neurodegenerative diseases. CV is sensitive to aging process and pathology but does not allow to discriminate between specific neurodegenerative diseases. D shows no significative change in pathological groups. However, since H index is correlated with Hoehn & Yahr scores and significantly lowered in patients suffering from Huntington's disease, we recommend it as a relevant supplement to CV. En ligne : https://www.medrxiv.org/content/10.1101/2020.01.31.20019455v1.full.pdf Permalink : ./index.php?lvl=notice_display&id=84497 Added Value and Clinical Significance of NonlinearVariability Indices of Walking Stride Interval inNeurodegenerative Diseases [document électronique] / Frédéric Dierick ; Charlotte Vandevoorde ; Frédéric Chantraine ; Olivier White ; Fabien Buisseret . - 2020. Cet article est une prépublication. doi: https://doi.org/10.1101/2020.01.31.20019455 Langues : Anglais (eng) Résumé : Though self-paced walking is highly stereotyped, the stride interval fluctuates from one stride to the next around an average value with a measurable statistical variability. In clinical gait analysis, this variability is usually assessed with indices such the standard deviation or the coefficient of variation (CV). The aim of this study is to understand the added value that nonlinear indices of walking stride interval variability, such as Hurst exponent (H) and Minkowski fractal dimension (D), can provide in a clinical context and to suggest a clinical significance of these indices in the most common neurodegenerative diseases: Parkinson, Huntington, and amyotrophic lateral sclerosis. Although evidence have been accumulated that the stride interval organization at long range displays a more random, less autocorrelated, gait pattern in neurodegenerative diseases compared with young healthy individuals, it is today necessary to recompute CV, H, and D indices in a unified way and to take into account aging impact on these indices. In fact, computed nonlinear indices of variability are mainly dependent on stride interval time series length and algorithms used, making quantitative comparisons between different studies difficult or even impossible. Here, we recompute these indices from available stride interval time series, either coming from our lab or from online databases, or made available to us by the authors of previously conducted research. We confirm that both linear and nonlinear variability indices are relevant indicators of aging process and neurodegenerative diseases. CV is sensitive to aging process and pathology but does not allow to discriminate between specific neurodegenerative diseases. D shows no significative change in pathological groups. However, since H index is correlated with Hoehn & Yahr scores and significantly lowered in patients suffering from Huntington's disease, we recommend it as a relevant supplement to CV. En ligne : https://www.medrxiv.org/content/10.1101/2020.01.31.20019455v1.full.pdf Permalink : ./index.php?lvl=notice_display&id=84497

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Adiabatic invariants drive rhythmic human motion in variablegravity / Nicolas Boulanger  

Public ISBD Titre : Adiabatic invariants drive rhythmic human motion in variablegravity Type de document : document électronique Auteurs : Nicolas Boulanger ; Fabien Buisseret ; V. Dehouck ; Frédéric Dierick ; Olivier White Année de publication : 2019 Langues : Anglais (eng) Résumé : Natural human movements are stereotyped. They minimise cost functions that include energy,a natural candidate from mechanical and physiological points of view. In time-changing envi-ronments, however, motor strategies are modified since energy is no longer conserved. Adiabaticinvariants are relevant observables in such cases, although they have not been investigated in hu-man motor control so far. We fill this gap and show that the theory of adiabatic invariants explainshow humans move when gravity varies. En ligne : https://arxiv.org/pdf/1906.08686.pdf Permalink : ./index.php?lvl=notice_display&id=84496 Adiabatic invariants drive rhythmic human motion in variablegravity [document électronique] / Nicolas Boulanger ; Fabien Buisseret ; V. Dehouck ; Frédéric Dierick ; Olivier White . - 2019. Langues : Anglais (eng) Résumé : Natural human movements are stereotyped. They minimise cost functions that include energy,a natural candidate from mechanical and physiological points of view. In time-changing envi-ronments, however, motor strategies are modified since energy is no longer conserved. Adiabaticinvariants are relevant observables in such cases, although they have not been investigated in hu-man motor control so far. We fill this gap and show that the theory of adiabatic invariants explainshow humans move when gravity varies. En ligne : https://arxiv.org/pdf/1906.08686.pdf Permalink : ./index.php?lvl=notice_display&id=84496

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Benefits of nonlinear analysis indices of walking stride interval in the evaluation of neurodegenerative diseases / Frédéric Dierick  

Public ISBD Titre : Benefits of nonlinear analysis indices of walking stride interval in the evaluation of neurodegenerative diseases Type de document : document électronique Auteurs : Frédéric Dierick ; Frédéric Chantraine ; Charlotte Vandevoorde ; Olivier White ; Fabien Buisseret Année de publication : 2020 Langues : Français (fre) Mots-clés : marche  analyse fractale  pathologies neurodégénératives Résumé : Indices characterising the long-range temporal structure of walking stride interval (SI) variability such as Hurst exponent (H) and fractal dimension (D) may be used in addition to indices measuring the amount of variability like the coefficient of variation (CV). We assess the added value of the former indices in a clinical neurological context. Our aim is to demonstrate that they provide a clinical significance in aging and in frequent neurodegenerative diseases such as Parkinson's disease, Huntington, and amyotrophic lateral sclerosis. Indices assessing the temporal structure of variability are mainly dependent on SI time series length and algorithms used, making quantitative comparisons between different studies difficult or even impossible. Here, we recompute these indices from available SI time series, either from our lab or from online databases. More precisely, we recompute CV, H, and D in a unified way. The average SI is also added to the measured parameters. We confirm that variability indices are relevant indicators of aging process and neurodegenerative diseases. While CV is sensitive to aging process and pathology, it does not discriminate between specific neurodegenerative diseases. H, which measures predictability of SI, significantly decreases with age but increases in patients suffering from amyotrophic lateral sclerosis. D, catching complexity of SI, is correlated with total functional capacity in patients with Huntington's disease. We conclude that the computation of H complements the clinical diagnosis of walking in patients with neurodegenerative diseases and we recommend it as a relevant supplement to classical CV or averaged SI. Since H and D indices did not lead to the same observations, suggesting the multi-fractal nature of SI dynamics, we recommend to open clinical gait analysis to the evaluation of more parameters. En ligne : https://luck.synhera.be/bitstream/handle/123456789/519/2020.01.31.20019455v1.ful [...] Permalink : ./index.php?lvl=notice_display&id=98162 Benefits of nonlinear analysis indices of walking stride interval in the evaluation of neurodegenerative diseases [document électronique] / Frédéric Dierick ; Frédéric Chantraine ; Charlotte Vandevoorde ; Olivier White ; Fabien Buisseret . - 2020. Langues : Français (fre) Mots-clés : marche  analyse fractale  pathologies neurodégénératives Résumé : Indices characterising the long-range temporal structure of walking stride interval (SI) variability such as Hurst exponent (H) and fractal dimension (D) may be used in addition to indices measuring the amount of variability like the coefficient of variation (CV). We assess the added value of the former indices in a clinical neurological context. Our aim is to demonstrate that they provide a clinical significance in aging and in frequent neurodegenerative diseases such as Parkinson's disease, Huntington, and amyotrophic lateral sclerosis. Indices assessing the temporal structure of variability are mainly dependent on SI time series length and algorithms used, making quantitative comparisons between different studies difficult or even impossible. Here, we recompute these indices from available SI time series, either from our lab or from online databases. More precisely, we recompute CV, H, and D in a unified way. The average SI is also added to the measured parameters. We confirm that variability indices are relevant indicators of aging process and neurodegenerative diseases. While CV is sensitive to aging process and pathology, it does not discriminate between specific neurodegenerative diseases. H, which measures predictability of SI, significantly decreases with age but increases in patients suffering from amyotrophic lateral sclerosis. D, catching complexity of SI, is correlated with total functional capacity in patients with Huntington's disease. We conclude that the computation of H complements the clinical diagnosis of walking in patients with neurodegenerative diseases and we recommend it as a relevant supplement to classical CV or averaged SI. Since H and D indices did not lead to the same observations, suggesting the multi-fractal nature of SI dynamics, we recommend to open clinical gait analysis to the evaluation of more parameters. En ligne : https://luck.synhera.be/bitstream/handle/123456789/519/2020.01.31.20019455v1.ful [...] Permalink : ./index.php?lvl=notice_display&id=98162

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Fine adaptive control of precision grip without maximum pinch strength changes after mediannerve mobilization / Frédéric Dierick  

Public ISBD Titre : Fine adaptive control of precision grip without maximum pinch strength changes after mediannerve mobilization Type de document : document électronique Auteurs : Frédéric Dierick ; J.-M. Brismée ; Olivier White ; Anne-France Bouché ; Céline Perichon ; Nastasia Filoni ; Vincent Barvaux ; Fabien Buisseret Année de publication : 2020 Note générale : Cet article est une prépublication. doi: https://doi.org/10.1101/2020.04.01.2004963 Langues : Anglais (eng) Résumé : Fine dexterity critically depends on information conveyed by the median nerve. While the effects of its compression andvibration are well characterized, little is known about longitudinal tension and excursion. Using a force-sensitive manipulandum,a numeric dynamometer and Semmes-Weinstein monofilaments, we examined the adaptations of precision grip control,maximum pinch strength and fingertips pressure sensation threshold before and immediately after the application of longitudinaltension and excursion mobilizations applied on the median nerve. Grip (GF) and load (LF) forces applied by the thumb,index and major fingers were collected in 40 healthy young participants during three different grip precision tasks along thedirection of gravity. For grip-lift-drop task, maximumGFandLFand their first time derivatives were computed. For up-downoscillations, means ofGFandLFand their variability were computed. For oscillations with up and down collisions, peaksofGFandLF, time delay betweenGFpeak and contact, and values ofGFandLFat contact were collected. Our findingsshow that median nerve mobilizations induce significant fine adaptations of precision grip control in the three different tasksbut mainly during grip-lift-drop and oscillations with collisions. Fingertips pressure sensation thresholds at index and thumbwere significantly reduced after the mobilizations. No significant changes were observed for maximum pinch strength. Weconclude that precision grip adaptations observed after median mobilizations could be partly explained by changes in cutaneousmedian-nerve mechanoreceptive afferents from the thumb and index fingertip En ligne : https://www.medrxiv.org/content/10.1101/2020.04.01.20049635v1.full.pdf Permalink : ./index.php?lvl=notice_display&id=84498 Fine adaptive control of precision grip without maximum pinch strength changes after mediannerve mobilization [document électronique] / Frédéric Dierick ; J.-M. Brismée ; Olivier White ; Anne-France Bouché ; Céline Perichon ; Nastasia Filoni ; Vincent Barvaux ; Fabien Buisseret . - 2020. Cet article est une prépublication. doi: https://doi.org/10.1101/2020.04.01.2004963 Langues : Anglais (eng) Résumé : Fine dexterity critically depends on information conveyed by the median nerve. While the effects of its compression andvibration are well characterized, little is known about longitudinal tension and excursion. Using a force-sensitive manipulandum,a numeric dynamometer and Semmes-Weinstein monofilaments, we examined the adaptations of precision grip control,maximum pinch strength and fingertips pressure sensation threshold before and immediately after the application of longitudinaltension and excursion mobilizations applied on the median nerve. Grip (GF) and load (LF) forces applied by the thumb,index and major fingers were collected in 40 healthy young participants during three different grip precision tasks along thedirection of gravity. For grip-lift-drop task, maximumGFandLFand their first time derivatives were computed. For up-downoscillations, means ofGFandLFand their variability were computed. For oscillations with up and down collisions, peaksofGFandLF, time delay betweenGFpeak and contact, and values ofGFandLFat contact were collected. Our findingsshow that median nerve mobilizations induce significant fine adaptations of precision grip control in the three different tasksbut mainly during grip-lift-drop and oscillations with collisions. Fingertips pressure sensation thresholds at index and thumbwere significantly reduced after the mobilizations. No significant changes were observed for maximum pinch strength. Weconclude that precision grip adaptations observed after median mobilizations could be partly explained by changes in cutaneousmedian-nerve mechanoreceptive afferents from the thumb and index fingertip En ligne : https://www.medrxiv.org/content/10.1101/2020.04.01.20049635v1.full.pdf Permalink : ./index.php?lvl=notice_display&id=84498

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Fractal analyses reveal independent complexity and predictability of gait / Frédéric Dierick in Plos One, vol.12, n°11 (Novembre 2017)  

Public ISBD [article]  inPlos One > vol.12, n°11 (Novembre 2017) Titre : Fractal analyses reveal independent complexity and predictability of gait Type de document : document électronique Auteurs : Frédéric Dierick ; Anne-Laure Nivard ; Olivier White ; Fabien Buisseret Année de publication : 2017 Langues : Anglais (eng) Résumé : Locomotion is a natural task that has been assessed since decades and used as a proxy to highlight impairments of various origins. Most studies adopted classical linear analyses of spatio-temporal gait parameters. Here, we use more advanced, yet not less practical, non-linear techniques to analyse gait time series of healthy subjects. We aimed at finding more sensitive indexes related to spatio-temporal gait parameters than those previously used, with the hope to better identify abnormal locomotion. We analysed large-scale stride interval time series and mean step width in 34 participants while altering walking direction (forward vs. backward walking) and with or without galvanic vestibular stimulation. The Hurst exponent  and the Minkowski fractal dimension D were computed and interpreted as indexes expressing predictability and complexity of stride interval time series, respectively. We show that  and D accurately capture stride interval changes in function of the experimental condition. Walking forward exhibited maximal complexity (D) and hence, adaptability. In contrast, any perturbation (walking backward and/or stimulation of the vestibular system) decreased it. Furthermore, walking backward increased predictability () through a more stereotyped pattern of the stride interval and galvanic vestibular stimulation reduced predictability. The present study demonstrates the complementary power of the Hurst exponent and the fractal dimension to improve walking classification. These holistic indexes can easily be interpreted in the framework of optimal movement complexity. Our developments may have immediate applications in rehabilitation, diagnosis, and classification procedures. En ligne : https://journals.plos.org/plosone/article/file?type=printable&id=10.1371/journal [...] Permalink : ./index.php?lvl=notice_display&id=84492 [article] Fractal analyses reveal independent complexity and predictability of gait [document électronique] / Frédéric Dierick ; Anne-Laure Nivard ; Olivier White ; Fabien Buisseret . - 2017. Langues : Anglais (eng) in Plos One > vol.12, n°11 (Novembre 2017) Résumé : Locomotion is a natural task that has been assessed since decades and used as a proxy to highlight impairments of various origins. Most studies adopted classical linear analyses of spatio-temporal gait parameters. Here, we use more advanced, yet not less practical, non-linear techniques to analyse gait time series of healthy subjects. We aimed at finding more sensitive indexes related to spatio-temporal gait parameters than those previously used, with the hope to better identify abnormal locomotion. We analysed large-scale stride interval time series and mean step width in 34 participants while altering walking direction (forward vs. backward walking) and with or without galvanic vestibular stimulation. The Hurst exponent  and the Minkowski fractal dimension D were computed and interpreted as indexes expressing predictability and complexity of stride interval time series, respectively. We show that  and D accurately capture stride interval changes in function of the experimental condition. Walking forward exhibited maximal complexity (D) and hence, adaptability. In contrast, any perturbation (walking backward and/or stimulation of the vestibular system) decreased it. Furthermore, walking backward increased predictability () through a more stereotyped pattern of the stride interval and galvanic vestibular stimulation reduced predictability. The present study demonstrates the complementary power of the Hurst exponent and the fractal dimension to improve walking classification. These holistic indexes can easily be interpreted in the framework of optimal movement complexity. Our developments may have immediate applications in rehabilitation, diagnosis, and classification procedures. En ligne : https://journals.plos.org/plosone/article/file?type=printable&id=10.1371/journal [...] Permalink : ./index.php?lvl=notice_display&id=84492

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Higher-derivative harmonic oscillators: stability of classical dynamics and adiabatic invariants / Nicolas Boulanger in The European Physical Journal C [périodique électronique], 79 (2019)  

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Motor strategies and adiabatic invariants: The case of rhythmic motion in parabolic flights / Nicolas Boulanger  

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