Objective: To explore changes in directed functional connectivity in four networks, namely the sensory-motor network (SMN), ventral-attention network (VAN), dorsal-attention network (DAN), and central-executive network (CEN) using an EEG-based mapping between patients with PD and healthy controls (HCs).

Background: Directed functional connectivity alterations within brain networks in patients with Parkinson’s disease (PD) are described using resting-state fMRI. However, EEG has been scarcely used to assess directed functional connectivity despite its high temporal resolution.

Method: Four-minute EEG at rest were recorded from 29 patients with PD (age 64.36±7.11, disease duration: 2.8±0.28 years) and 28 HCs (age 60.82±7.47). Network’s hubs were defined using fMRI-based binary masks and their electrical activity during the four-minute EEG recording at rest was calculated using the LORETA (low-resolution electromagnetic tomography). Directed functional connectivity between each network’s hub-pairs was calculated for the theta, alpha and beta bands using temporal partial directed coherence (tPDC). The number of significant tPDCs within each network and the strength of each significant tPDC were compared between the groups.

Results: The percent of significant tPDCs was lower in the CEN and DAN in patients with PD compared to HCs while no differences between the groups were observed in the SMN and VAN (group*network interaction: F=5.943, p<0.001). Similar findings were observed in theta, alpha, and beta bands (group*band effect: F=0.914, p=0.401). However, comparison between the strength of each tPDCs revealed significant difference between groups only in the VAN, PD patients showing greater tPDCs strength compared to HCs (p<0.001).

Conclusion: Our results demonstrate reduced connectivity in the CEN and DAN, and increased connectivity in the VAN in PD patients. In the SMN, the differences between the groups are at specific connections. These results indicate a complex pattern of DFC alteration within major brain networks, reflecting the co-occurrence of impairment and compensatory mechanisms processes taking place in PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/eeg-based-mapping-of-resting-state-functional-brain-networks-in-patients-with-parkinsons-disease/