Article: Non-linear Granger causality and its frequency decomposition in decoding human upper limb movement intentions Journal: International Journal of Biomedical Engineering and Technology (IJBET) 2013 Vol.12 No.1 pp.1 - 25 Abstract: Non-linear Granger Causality (GC) can detect directional influence of signals between multiple locations through a non-linear predictive approach using Radial Basis Functions (RBF). However, the directional relations in frequency domain are often lost. In this paper, we investigate how the non-linear causal relationship at different frequency bands can be extracted by the proper linearisation process. The difference between the non-linearly and linearly fitted signals was used to determine if the frequency components can be approximated. This strategy was implemented and evaluated on a Brain Computer Interface (BCI) application to decode the intended directions of an imagined arm reaching movement (left, right and forward) using 128 surface electroencephalography (EEG) electrodes. The causal influence of the active recording sites was found to be unique with respect to the direction of the intended movement. Particularly, the left and right reaching directions were found to be highly separable in the theta rhythm (3-8 Hz). Inderscience Publishers - linking academia, business and industry through research

Title: Non-linear Granger causality and its frequency decomposition in decoding human upper limb movement intentions

Authors: Meng Ting Liu; Ching-Chang Kuo; Alan W.L. Chiu

Addresses: Biomedical Engineering, Louisiana Tech University, 818 Nelson Ave, Ruston, LA 71272, USA ' Biomedical Engineering, Louisiana Tech University, 818 Nelson Ave, Ruston, LA 71272, USA ' Applied Biology and Biomedical Engineering, Rose-Hulman Institute of Technology, 5500 Wabash Ave, Terre Haute, IN 47803, USA

Abstract: Non-linear Granger Causality (GC) can detect directional influence of signals between multiple locations through a non-linear predictive approach using Radial Basis Functions (RBF). However, the directional relations in frequency domain are often lost. In this paper, we investigate how the non-linear causal relationship at different frequency bands can be extracted by the proper linearisation process. The difference between the non-linearly and linearly fitted signals was used to determine if the frequency components can be approximated. This strategy was implemented and evaluated on a Brain Computer Interface (BCI) application to decode the intended directions of an imagined arm reaching movement (left, right and forward) using 128 surface electroencephalography (EEG) electrodes. The causal influence of the active recording sites was found to be unique with respect to the direction of the intended movement. Particularly, the left and right reaching directions were found to be highly separable in the theta rhythm (3-8 Hz).

Keywords: nonlinear Granger causality; brain computer interface; BCI; motor intention; electroencephalograms; EEG; frequency decomposition; upper limb movements; limb movement intentions; arm reaching movement.

DOI: 10.1504/IJBET.2013.056282

International Journal of Biomedical Engineering and Technology, 2013 Vol.12 No.1, pp.1 - 25

Received: 15 Oct 2012
Accepted: 01 Apr 2013
Published online: 27 Sep 2014 *

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Title: Non-linear Granger causality and its frequency decomposition in decoding human upper limb movement intentions

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