Detection of Neurovascular Coupling in Full-Term Neonates Using Wavelet Coherence and Phase-Locking Value

This study proposes a new method to monitor neurovascular coupling and to help determine the level of brain injury in full-term neonates with Hypoxic Ischemic Encephalopathy (HIE). The wavelet coherence method is used to assess the coupling between the regional cerebral oxygen saturation (rSO2) as measured by NIRS and the lower envelope of EEG power in that region of the brain. This paper also provides methods for the visualization of the phase-locking value between these signals based on both the cross-wavelet and the Hilbert Transform methods. The preliminary results presented in this paper show that the lower envelope of EEG power is much better than the standard EEG power signal for the differentiation between Normal-Mild and Abnormal-Moderate HIE cases using wavelet coherence. On our limited dataset, a clear reduction in both the phase-locking value and the mean coherence was observed in the 0.25-1 mHz frequency range with the increase in severity of the brain injury, from mild to moderate HIE.