Testing for Nonlinearity in Functional Near-Infrared Spectroscopy of Brain Activities by Surrogate Data Methods
J Physiol Sci Vol.58, No.1 pp.47-52
Abstract: Methods of contemporary physics are increasingly important for biomedical research. For a multitude of diverse reasons there exists a gap between the practitioners of biomedicine and modern physics methodologies. In this work, the technique of surrogate data has been used as a method to test for the linearity or nonlinearity of biomedical functional near-infrared spectroscopy (fNIRS) signals observing brain activities. Throughout three different surrogate tests, the third-order autocovariance, the asymmetry resulting from time reversal, and the delay vector variance, the dynamic response of brain activities through fNIRS biomedical signals is very likely to be a nonlinear system.
Chaos and Fractals Laboratory, Department of Electrical Engineering, Nagaoka University of Technology, Niigata, 940-2188 Japan. khoa@ieee.org
Copyright© 2007 by The Physiological Society of Japan