Neural Mechanisms of Motor-Cognitive Synergy in Parkinson’s Disease: A Pilot EEG-Based Functional Brain Network Study

Background: Parkinson's disease (PD) patients suffer from motor-cognitive dysfunction due to the degeneration of nigrostriatal dopamine neurons in the midbrain. PD brain dysfunction can be effectively understood by analyzing cortical Electroencephalography (EEG) signals, However, most of the existing studies have focused on exploring single PD motor dysfunction without considering the potential relationship between both motor and cognitive. Therefore, the aim of the present study was to investigate the physiological characteristics of the cortical neural network of motor-cognitive functions in the brains of PD patients by comparing the brain functional properties of the subjects under motor task, cognitive task, and motor-cognitive dual-tasks. Method: In this study, we designed a motor-cognitive dual-task experimental paradigm to collect EEG signals from 13 PD patients and 13 healthy people (HP). Meanwhile, we combined qualitative and quantitative methods to analyze the motor-cognitive functional characteristics of the brains of HP and PD patients under multilevel multi-task conditions by EEG traceability analysis, brain functional network analysis, and statistical analysis. Result: Our results show that the activation intensity of motor function brain regions and cognitive function brain regions is higher and the out-degree of functional brain region externality is significantly higher in HP and PD under the motor-cognitive dual-task. Further analysis showed that the average path length of the functional brain network was shorter and the average clustering coefficient was higher in the dual-task. The strength of node connections and the efficiency of information transfer in the PD whole-brain functional network were weakened compared to HP. Conclusion: This study confirmed that neural synergies exist between motor and cognitive functions in the brains of HP and PD, even though PD patients' macroscopic motor and cognitive functions are disrupted by structural brain lesions, they still have this motor-cognitive synergistic neural mechanism. This study is the first to explore the potential synergistic relationship between motor and cognitive functions in the brains of PD patients at the level of the cortical neurofunctional brain network, which provides a theoretical basis for the rehabilitation of motor-cognitive dual dysfunction in PD patients.