PAC and beta band power were modulated by dopaminergic medication in a very similar way. Indeed, a strong correlation between their mean values was found for both the low- and high-beta range (Table 1). We next considered whether this relation also holds regarding the exact frequencies at which their peak values occur. Most PAC involved modulation of HFOs by the phase of the low beta band activity, and within this range the phase frequency corresponding to the highest PAC value tended to coincide with or was close to the spectral peak frequency (Fig. 3A). Analogous histograms for the high-beta range showed less consistency between the frequency of highest PAC and spectral peak frequencies. Similarly, the distribution of mean phase angles only significantly differed from a uniform distribution for the low-beta range (mean = 8.8°, p = .022) but not the high-beta range (Fig. 3B). These findings indicate a larger variability in PAC for the high-beta range. Group-level PAC mainly occurred within the low-beta range, and predominantly for frequencies close to the peak in the power spectrum.
