Facilitating Joint Chaos and Fractal Analysis of Biosignals through Nonlinear Adaptive Filtering

• Published in: PloS one Vol. 6; no. 9; p. e24331
• Main Authors: Gao, Jianbo, Hu, Jing, Tung, Wen-wen
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 06.09.2011; Public Library of Science (PLoS)
• Subjects: Adaptive algorithms; Adaptive filters; Algorithms; Analysis; Animals; Bands; Biological effects; Biology; Chaos theory; Decomposition; EEG; Electroencephalography; Electromagnetic wave filters; Engineering; Epilepsy; Epilepsy - physiopathology; Fractal analysis; Fractals; Humans; Linear filters; Medicine; Multiscale analysis; Noise; Noise control; Noise reduction; Nonlinear Dynamics; Nonlinear systems; Physics; Physiology; Rhythms; Seizures; Signal Processing, Computer-Assisted; Time series; Trends; Wavelet analysis; Indiana; United States > US
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0024331

Chaos and random fractal theories are among the most important for fully characterizing nonlinear dynamics of complicated multiscale biosignals. Chaos analysis requires that signals be relatively noise-free and stationary, while fractal analysis demands signals to be non-rhythmic and scale-free. To facilitate joint chaos and fractal analysis of biosignals, we present an adaptive algorithm, which: (1) can readily remove nonstationarities from the signal, (2) can more effectively reduce noise in the signals than linear filters, wavelet denoising, and chaos-based noise reduction techniques; (3) can readily decompose a multiscale biosignal into a series of intrinsically bandlimited functions; and (4) offers a new formulation of fractal and multifractal analysis that is better than existing methods when a biosignal contains a strong oscillatory component. The presented approach is a valuable, versatile tool for the analysis of various types of biological signals. Its effectiveness is demonstrated by offering new important insights into brainwave dynamics and the very high accuracy in automatically detecting epileptic seizures from EEG signals.