Fig 5. Pain sensitivity across individuals is reflected in the strength of neural entrainment: Phase.

The across-participants variability in perceived pain intensity was also reflected in the phase relationship between the entrained oscillations and the stimulus profile. For each individual, the mean of high-pain (A-C), low-pain (D-F), or auditory (G-H) peak ratings was plotted against the phase difference between the 0.1-Hz oscillation at central electrodes and the stimulus (“phase relation”). To evaluate this relationship, we fitted a single-cycle cosine function (red lines). Coefficient of determination (R²) of the cosine fit was tested by random permutation of the phase across participants. Individuals who rated the nociceptive stimulus as more painful entrained more closely to the phase of the nociceptive input (i.e., with a phase relation around 0). This relationship was preserved not only within condition (B,F) but also across conditions (A,C-E). Importantly, such relationship was not present in the auditory conditions (G-H). N = 30 participants. Data underlying these plots can be found in S1 Data. VAS, visual analogue scale.