Objective: The aim of this study is to estimate the level of beta synchronization of the subthalamic nucleus (STN) evoked by internally and externally generated movements in parkinsonian patients and compare it between OFF and ON states.

Background: According to the motor control hypothesis, movements evoked by externally-triggered (ET) are carried out using the cerebello-thalamocortical loops, while internally-guided (IG) movements involve striato-thalamocortical connections [1]. At the same time, it is known that patients with Parkinson’s disease (PD), have difficulty with self-initiated movements because of an initiation deficit resulting from basal ganglia dysfunction.

Method: Four patients, who had DBS surgery, were undergoing postoperative multichannel registration of STN local potentials (LFP) and EMG of the studied forearm muscles in OFF and ON states. During the study, patients were asked to perform motor tests triggered by external verbal commands, as well as self-initiated tests. We analyzed 3 pairs of bipolar LFPs in each hemisphere using a spectral and wavelet analysis.

Results: In most cases, we observed a significant increase or decrease of beta oscillations in contralateral STN during IG movements and insignificant changes during ET movements in OFF state patients. It is important to note that the most robust changes of the beta synchronization level were observed in ipsilateral STN for both IG and ET motor tests. The differences in beta oscillations disappeared between IG and ET movement after L-dopa treatment.

Conclusion: Our data showed that changes in pathological beta oscillations are associated to a greater extent with IG movement. We also found the significance of beta oscillations in the ipsilateral STN for motor control of voluntary movements in PD. 
The study was funded by the Russian Foundation for Basic Research (19-315-90097 and the Russian Science Foundation (21-75-10152)

References: [1] Sen, S., Kawaguchi, A., Truong, Y., Lewis, M. M., & Huang, X. (2010). Dynamic changes in cerebello-thalamo-cortical motor circuitry during progression of Parkinson’s disease. Neuroscience, 166(2), 712-719

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MDS Abstracts - https://www.mdsabstracts.org/abstract/beta-synchronization-of-the-subthalamic-nucleus-during-self-initiated-and-externally-generated-movement-in-parkinsonian-patients-in-off-and-on-states/