Objective: The aim of the current study is to investigate the frequency characteristics of beta activity in Parkinson’s disease. We hypothesized that beta peak central frequency along with beta power could reflect motor state in PD. To check our hypothesis, we test whether beta peak central frequency differs between the OFF and ON states.

Background: The beta oscillations is proposed to be one of biomarkers of motor symptoms in Parkinson’s disease. The frequency characteristics of pathological activity are still poorly understood, but there is evidence in favor of the applicability of beta peak central frequency as a biomarker of motor symptoms [1].

Method: We collected postoperative LFP data from 6 patients with PD. All patients underwent the implantation of bilateral STN DBS electrodes with external lead. We analyzed LFP spontaneous activity before and after levodopa administration (OFF and ON state). Patients’ condition was assessed by UPDRS motor tests. All patients showed improvement in clinical symptoms after levodopa administration. Local field potentials were recorded from bilateral DBS electrodes, each with 8 contacts. On the basis of these records, we obtained 30 bipolar signals. Then we calculated the spectral power, isolated peaks in the beta band (14-30 Hz), and estimated the central frequency of the peaks. Then we compared the peak central frequency before and after levodopa administration (ON and OFF state) using linear mixed models.

Results: We found that the mean power in the beta range decreases after levodopa administration. Furthermore, we compared the central frequency of the beta peak between OFF and ON states and found that after levodopa administration the beta peak shifts towards higher frequency: the central frequency of the beta peak in the ON state was significantly higher than in the OFF state (F_1,518 = 27.2, p < 0.001; median 24.7 Hz in ON state and median 23.3 Hz in OFF state).

Conclusion: Our findings indicate that the central frequency of the beta peak may be a potential biomarker of motor symptoms in Parkinson’s disease. Further investigations of frequency parameters are needed, but our finding may contribute to full understanding of PD electrophysiological correlates and provide basis for DBS technology improving.

References: 1. Iskhakova, L., et al. “Modulation of dopamine tone induces frequency shifts in cortico-basal ganglia beta oscillations.” Nature communications 12.1 (2021): 1-17

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MDS Abstracts - https://www.mdsabstracts.org/abstract/lfp-beta-frequency-off-on-shift-in-subthalamic-nucleus-in-parkinsons-disease/