Fig. 5

No change in primary and secondary somatosensory cortex slow-5 (0.01–0.027 Hz) power (low pain vs. high pain FOP patients). Frequency analyses reveal no significant differences in power within the slow-5 sub-band across all channels distributed over the primary and secondary somatosensory cortex. Calculation of effect sizes (Cohen’s d (Range): 0.03–0.79) demonstrated a low to moderate pain-dependent effect on slow-5 power in somatosensory cortices. Mean power spectral density and standard error (shaded area) across all sub-bands (i.e., slow-1 to slow-5) are plotted for low clinical pain (Pain Level: 0–3; N = 5) and high clinical pain (Pain Level: 4–10; N = 5) FOP cohorts. Clinical pain intensity levels from each FOP patient were collected just prior to acquisition of a six-minute resting-state fNIRS scan. Significant correlation was not detected between clinical pain intensity ratings and slow-5 power (Correlation (r): − 0.04 to 0.23). While a trend towards higher (relative to the low pain FOP group) power in the slow-4 sub-band (Channel C10) for the high pain FOP cohort was observed, a significant intergroup difference was not present (p = 0.137)