Our measures of spectral power and PAC hence included: mean low-beta power, mean high-beta power, mean low-beta/HFO PAC, mean high-beta/HFO PAC, and mean HFO power. We were interested in their predictive value in explaining the severity of motor impairments manifest contralateral to the STN sites. These impairments were quantified via UPDRS scores of hemibody bradykinesia and rigidity for both ON and OFF medication states. Left/right hemibody scores were derived as the sum of the following items: 3.3 rigidity upper extremity, 3.3 rigidity lower extremity, 3.4 finger tapping, 3.5 hand movements, 3.6 pronation–supination movements of hands, 3.7 toe tapping, and 3.8 leg agility. We considered left and right STN sites from individual patients as independent samples, as well as values obtained during the ON and OFF medication state for each patient. These were combined into a single data vector comprising 101 samples. This resulted in a large range of UPDRS scores, which may be more suitable for revealing significant correlations in the presence of large inter-subject variability in power and PAC values.
