Disorganization of Equilibrium Directional Interactions in the Brain Motor Network of Parkinson’s Disease: New Insight of Resting State Analysis Using Granger Causality and Graphical Approach

Parkinson’s disease (PD) is a progressive neurological disorder characterized by tremor, rigidity, and slowness of movements. Particularchanges related to various pathological attacks in PD could result in causal interactions of the brain network from resting state functionalmagnetic resonance imaging (rs?fMRI) data. In this paper, we aimed to disclose the network structure of the directed influences over thebrain using multivariate Granger causality analysis and graph theory in patients with PD as compared with control group. rs-fMRI at restfrom 10 PD patients and 10 controls were analyzed. Topological properties of the networks showed that information flow in PD is smallerthan that in healthy individuals. We found that there is a balanced local network in healthy control group, including positive pair-wisecross connections between caudate and cerebellum and reciprocal connections between motor cortex and caudate in the left and righthemispheres. The results showed that this local network is disrupted in PD due to disturbance of the interactions in the motor networks.These findings suggested alteration of the functional organization of the brain in the resting state that affects the information transmissionfrom and to other brain regions related to both primary dysfunctions and higher-level cognition impairments in PD. Furthermore, weshowed that regions with high degree values could be detected as betweenness centrality nodes. Our results demonstrate that propertiesof small?world connectivity could also recognize and quantify the characteristics of directed influence brain networks in PD.