Objective: The main goal of this work relies on the study of the desynchronization of the sensorimotor rhythms in Parkinson’s disease (PD). Electrophysiological cortical activity of PD patients is captured while they execute a motor task before and after performing an endogenous neuromodulation (NM) intervention.

Background: The event-related desynchronization (ERD) is a neurophysiological phenomenon that reflects the decay of the EEG signal power accompanying the performance of motor tasks [1]. According to [2], PD patients present an excessive beta synchronization in motor cortex that may be causally related to this pathology. Since ERD physiological role seems to be associated to the coordination of the motor function, it may represent a valuable electrophysiological biomarker for assessing the changes produced by a NM therapy.

Method: 11 PD patients (4 women; Age: 62.18±8.18, 50-73; Years from onset: 5.91±3.75, 2-14; UPDRS: 15.55±7.29, 5-32; Levodopa equivalent dose (mg): 443±218, 100-710, 10 right-handed), participated in this study. The patients carried out 15 trials of a wrist extension (WE) task, with the right hand and then with the left hand, before and after 8 endogenous NM sessions. PD patients execute each run of the WE task following the cue-paced paradigm shown in Figure 1. During the wrist extension task, EEG signals were recorded from 9 central positions. The Power Spectral Density (PSD) were estimated for frequencies between 2-30 Hz. [figure1] The ERD is calculated in the movement preparation and movement window, relative to the baseline period, for both hands in the alpha and beta frequency bands. The ERD is featured by average value (AV) and minimum value (MV) of desynchronization in the selected temporal window.

Results: Results obtained show statistically significant differences in the two ERD features between the pre and post NM intervention (Table 1). [table1]

Conclusion: Most significant changes in ERD parameters are detected in the dominant hand. Mainly, the NM affects the average and minimum values of the ERD. For the right hand, the desynchronization is greater when patients perform a motor task after the NM intervention. The remaining changes are located in the sensorimotor cortex. For the left hand, the sole significant change is located in the premotor area in the beta band.

References: [1] G. Pfurtscheller and F.H. Lopes da Silva, “Event-related EEG/MEG Synchronization and Desynchronization: Basic Principles,” Clinical Neurophysiology, vol. 110, pp. 1842–1857, 1999. [2] S. Esmail and D.E.J. Linden, “Neural Networks and Neurofeedback in Parkinson’s disease”, NeuroRegulation, vol. 1(3-49), pp. 240-272, 2014.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/effects-of-the-neuromodulation-of-sensorimotor-rhythms-on-the-event-related-desynchronization-phenomenon-in-parkinsons-disease/