Orthogonalized partial directed coherence for functional connectivity analysis of newborn EEG

The aim of this study is to develop a time-frequency method and test its applicability to investigating directional cortical connectivity in the newborn brain considering the effect of volume conduction. We modified time-varying partial directed coherence (tv-PDC) based on orthogonalization of the MVAR model coefficients to deal with the effect of mutual independent sources. The novel measure was then tested using a simulated signal with feature dimensions relevant to EEG activity. From the neonatal EEG responses evoked by flash light stimuli (1Hz), we extracted the directional interactions over time within each hemisphere. The results suggest that the method is able to detect directed information flow within a sub-second time scale in nonstationary multichannel signals (such as newborn EEG) and attenuate the problematic effect of volume conduction for multichannel EEG connectivity analysis.Scopu