Data-driven wavelet coherence approach to assess neurovascular coupling in neonatal hypoxic–ischemic encephalopathy

Figures

• 

  Fig. 1. NVC between aEEG and cerebral tissue oxygen saturation (SctO2). Example of direct data simultaneously recorded SctO2 (a) and aEEG (b), with corresponding NVC (c) calculated using WTC for a neonate with mild HIE. The color gradient in the NVC plot represents coherence amplitude: red indicates strong coupling between SctO2 and aEEG, and blue indicates the absence of coupling without resorting to Monte Carlo simulation.

• 

  Fig. 2. Comparison of NVC in non-therapeutic hypothermia (non-TH) and TH groups. NVC between aEEG and cerebral tissue oxygen saturation (SctO2), assessed using wavelet transform coherence. The average coherence is shown for neonates in the non-TH (a) and TH (b) groups during the first 20 h of recording. Cluster-based permutation test identified significant timescale regions (c), with Z-statistic values indicating the direction of group differences. Red regions indicate higher NVC in the non-TH group, and blue regions indicate higher NVC in the TH group. A significant difference was observed at timescales of 25 to 60 min (0.28 to 0.67 mHz on Y-axis).

• 

  Fig. 3. Average coherence values across the 20-h recording period by timescale. The average NVC across all participants is shown, with the non-TH group in blue and the TH group in red. Shaded areas represent the standard error of the mean. Reduced coherence in the TH group is evident at the 25- to 60-min scale (0.28 to 0.67 mHz).

• 

  Fig. 4. NVC within the 25- to 60-min timescale. (a) Average coherence across participants in the therapeutic hypothermia (TH, red) and non-TH (blue) groups within the 25- to 60-min scale (0.28 to 0.67 mHz) over 20 h. Shaded areas indicate standard error of the mean. Linear mixed-effects modeling showed significant effects of group, time, and group × time interaction (P<0.001). Coherence was lower in the TH group, with group differences during the first 6 h remaining significant after Bonferroni adjustment (p<0.05). (b) Average coherence during 0 to 6 h was significantly lower in the TH group (p=0.010).