Time-frequency based Coherence and Phase Locking Value Analysis of Human Locomotion Data using Generalized Morse Wavelets

Time-frequency analysis is a powerful and popular tool for studying time-varying properties of non-stationary neurophysiological signals. In this study, time-frequency based coherence and phase locking value (PLV) analysis using generalized Morse wavelets are presented. The methods are applied to pairs of surface EMG signals recorded from leg muscles during treadmill walking in healthy human subjects. Time-frequency based coherence and PLV analysis in this study detect similar patterns of 8-15 Hz and 15-20 Hz common modulation of EMG during locomotion. Our results suggest that a combination of both methods would be suitable for investigating and characterising non-stationary neurophysiological data. An understanding of the basic principles of normal locomotion can further provide insight into pathological locomotion deficits.