TITLE:
Loss of Lag Response Curvilinearity of Gait Poincare Plot Indices in Neurodegenerative Disorders
AUTHORS:
Chandrakar Kamath
KEYWORDS:
Gait Signal, Neurodegenerative Disorder, Nonlinear Dynamics, Ordinal Patterns, Symbolic Analysis
JOURNAL NAME:
Open Access Library Journal,
Vol.2 No.6,
June
19,
2015
ABSTRACT: It is reported in the literature that the temporal structure of gait
variability in healthy subjects exhibits deterministic processes where not only
each stride is correlated with the neighbouring strides (i.e. short-range correlations), but at least on a statistical
basis, with tens and hundreds of preceding and following strides (i.e. long-range correlations). Thus, an
analysis hinging on a conventional gait Poincare plot with lag one which implicitly
assumes that the current stride is influenced by the immediately preceding
stride will likely underestimate the role of the autocovariance function of stride
intervals. This implies that a series of lagged gait Poincare plots can potentially
provide more information by reflecting short-range correlations of gait
variability through the behaviour of Poincare indices in health as well as
disease. Hence, in this study in the context of short-term variability, we
assessed a curvilinear relation between lag (1 - 6) and Poincare indices in
normal subjects and patients with neurodegenerative disorders. We found that
while normal subjects exhibited this curvilinearity, the patients with
neurodegenerative disorders showed its loss.