Objective: The presented work explores electrophysiological changes in brain dynamics described by EEG microstates and the effect of deep brain stimulation (DBS) of subthalamic nucleus (STN) in patients with Parkinson’s disease (PD).

Background: Even though previous functional magnetic resonance imaging (fMRI) studies explored the mechanisms of DBS in whole brain scale [1], sub-second temporal resolution of high density (HD) EEG seems to be a promising source of information about changes in spatiotemporal brain dynamics [2].

Method: We analyzed resting state HD EEG in 37 PD patients with late motor complications treated by STN-DBS and 37 matched healthy controls (HC). EEG microstates were calculated in preprocessed 204 channels of two 5 minutes sessions (DBS OFF and ON state) for PD and one 5 minutes session for HC, which form three groups (PD DBS OFF, PD DBS ON, HC). Microstate parameters (global explained variance, mean duration, time coverage, occurrence) were then compared between groups. Frequency analysis and source imaging were also provided for temporal presence of each microstate.

Results: We found five distinct microstate (MS) maps with similar topographies across all three groups. Two MSs significantly differ (p<0.05 FDR) in global explained variance and time coverage between PD groups and HC. Sources of these MSs are localized to areas related to salience and default-mode networks. Another MS significantly differ (p<0.05 FDR) in global explained variance and time coverage between PD DBS OFF and ON and between PD DBS OFF and HC group. Sources of the MS are localized into frontoparietal areas. Beta power evaluated in temporal segments labeled by that MS is the highest in PD DBS OFF group and the lowest in HC group.

Conclusion: EEG microstate analysis of resting-state data allows to investigate brain dynamics in PD patients treated by DBS. Approach revealed changes in MS parameters, which are related to PD, not affected by DBS and localized to brain areas related to default-mode functional networks. Moreover, it identified alterations, which are partially reversed by DBS toward to HC and localized to frontoparietal areas.

References: [1] Kim J, et al. Abnormal intrinsic brain functional network dynamics in Parkinson’s disease. Brain. 2017; 140.11: 2955-2967.
[2] Michel CM, Koenig T. EEG microstates as a tool for studying the temporal dynamics of whole-brain neuronal networks: A review. Neuroimage. 2018;180:577–593.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/altered-brain-dynamics-in-parkinsons-disease-patients-treated-by-deep-brain-stimulation/