Fig. 1: Methodology.

a Schematic setup of multichannel NIRS monitoring. Four emitter–detector pairs (channels) were placed at the frontal (anterior), posterior (posterior), left temporal (left), and right temporal (right) regions, respectively. The anterior channel was adjacent to the standard cerebral oximeter probe and thereby used as a reference channel: anterior–posterior (A–P), anterior–left (A–L), and anterior–right (A–L) pairs. b Analysis of regional difference in cerebral hemodynamics. For each paired comparison shown in a, wavelet transform was applied to characterize coherence in a time–frequency ___domain, as demonstrated in the right panel. In that panel, the x-axis in that represents time and the y-axis represents scale. The color scale represents the magnitude of squared cross-wavelet coherence R2, which ranges from 0 (no coherence) to 1 (complete coherence). The black line contouring red areas designate areas of significant coherence (p < 0.05). The arrows designate the relative phase between the two paired signals. c Analysis of regional difference in cerebral autoregulation.