Phase synchronization analysis of multi-channel Local Field Potentials based on high-resolution wavelet transform

The present study investigates phase synchronization of multi-channel Local Field Potentials (LFPs) in the prefrontal cortex of rats during the awake and anesthetic states via high-resolution wavelet transform. High-resolution wavelet transform, i.e. wavelet packet transform, evolves from the wavelet transform. LFPs are decomposed to wavelet packet components with equal bandwidth of 0.45Hz. Every channel´s instantaneous phase is obtained by applying Hilbert transform. The cross-correlation coherence is calculated in a sliding 50-ms window with 50% overlap. The results show that the linear correlation between the reference channel and each of the other channels increases during the anesthetic state comparing with the wake state in the bands of 2-2.5Hz, 2.5-3Hz, 3-3.5Hz and 3.5-4Hz. The conclusion is that the high-resolution wavelet transform is more effective and accurate than wavelet transform in analyzing LFPs. This analysis may provide further support for analyzing LFPs in brain.