title: Testing for nonlinearity in functional near-infrared spectroscopy of brain activities by surrogate data methods.
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.
authors.affiliation: Chaos and Fractals Laboratory, Department of Electrical Engineering, Nagaoka University of Technology, Niigata, Japan. khoa@ieee.org
authors.forename: Truong Q D
authors.initials: TQ
authors.lastname: Khoa
authors.forename: Hoang M
authors.initials: HM
authors.lastname: Thang
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nakagawa
mesh_terms: D001921:Brain / Q000502:physiology*; D006801:Humans; D008959:Models, Neurological; D017711:Nonlinear Dynamics; D012815:Signal Processing, Computer-Assisted; D019265:Spectroscopy, Near-Infrared; D013269:Stochastic Processes