Fig. 6

Normalized mean and standard deviation of permutation feature importance for predicting perceived pain severity. Each feature represents functional connectivity between channel pairs (Ch) associated with either HbO or HbR signals. Channels 1–24 are located in the prefrontal cortex, channels 25–29 in the right parietal lobe, channels 30–39 in the superior frontal gyrus, and channels 40–44 in the left parietal lobe.