Objective: The aim of the current study was to analyze local field potentials (LFP) recorded from globus pallidus (GP) during voluntary movements in patients with Parkinson’s disease (PD) and cervical dystonia (CD).

Background: Numerous electrophysiological studies associate hypokinetic symptoms of PD primarily with the pathological synchronization of oscillations in the beta range (12–30 Hz) between the basal ganglia (BG) and the motor cortex (Brown et al., 2001, Eisinger et al., 2020). At the same time the question of the physiological or pathological role of these oscillations in motor control remains controversial.

Method: We performed postoperative recordings of local field potentials (LFP) using electrodes for deep brain stimulation (DBS) implanted in the globus pallidus (GP) in PD and CD patients. Recordings of forearm muscle activity (EMG) were obtained simultaneously with LFPs. During the recording sessions, patients were instructed to clench their hand into a fist 10 times in response to a verbal command. We performed peievent spectral and wavelet analysis to study time-frequency dynamics of pallidal oscillations during voluntary movement.

Results: We found low amplitude broad 12-30 Hz beta activity in CD and high amplitude high beta or both high and low beta activity, which was completely suppressed by LDOPA in PD. We observed beta event-related desynchronization (ERD) and subsequent hypersynchronization in both CD and PD groups during voluntary movements. At the same time ERD in CD group started significantly earlier then in PD and finished at the movement onset. It is important to note that this beta desynchronization was accompanied with complete muscle relaxation starting 0,8-1 sec before movement. In the PD group we observe only short-term (100-200 ms) pre-movement muscle relaxation and ERD response finished in 0,5-1 sec after movement onset.

Conclusion: We found differences in time dynamics of pallidal beta desynchronization during voluntary movement in PD and CD patients. We suppose that prolonged desynchronization before movement onset observed in the CD group could help to select the necessary motor program, which is disrupted in Parkinson’s disease. The study was funded by Russian Science Foundation (RSF), project number 23-15-00487.

References: Brown P. Dopamine Dependency of Oscillations between Subthalamic Nucleus and Pallidum in Parkinson’s Disease / P. Brown, A. Oliviero, P. Mazzone, A. Insola, P. 90 Tonali, V. Di Lazzaro // The Journal of Neuroscience. – 2001. – Vol. 21. – № 3. – P. 1033-1038.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/dynamics-of-pallidal-beta-activity-during-voluntary-movement-in-parkinsons-disease-and-cervical-dystonia/