Using a relatively large cohort of patients, we have demonstrated that phase–amplitude coupling between beta band activity and HFO in the subthalamic nucleus of Parkinson’s disease patients correlates with severity of bradykinesia/rigidity. Higher PAC values were associated with stronger motor impairment. Despite the strong correlation between PAC and beta band spectral power, results suggested that PAC might have slightly superior predictive value in explaining the variability in measured UPDRS scores. We found little evidence for a coupling between HFO in the STN and beta band activity in cortical motor areas. A dissociation was made between low- and high-beta frequency ranges as medication-induced effects on PAC and spectral power within the STN were found to be confined to the former, whereas coherence between the STN and cortical motor regions was predominant in the latter.
