Altered Granger causality connectivity within motor-related regions of patients with Parkinson's disease: a resting-state fMRI study

Purpose Although numerous clinical neuroimaging studies have demonstrated that there are functional abnormalities of motorrelated regions in patients with Parkinson's disease (PD) by resting-state functional magnetic resonance imaging (fMRI), little studies have explored the causal interactions within these motor-related regions. The present study aimed to examine Granger causality connectivity patterns within motor-related regions in PD patients. Methods Resting-state fMRI was conducted to investigate the causal connectivity differences within motor-related regions between 17 PD patients and 17 matched healthy controls. Subsequently, the relationship between the Unified Parkinson's Disease Rating Scale scores and causal connectivity values within motor-related regions was examined in PD patients. Results An increased causal connectivity from the left premotor cortex (PMC) to right primary motor cortex (M1) was found in PD patients compared with that of healthy controls. Also, increased causal flow from the PMC to M1 was negatively correlated with motor scores. Conclusion PD patients have abnormal causal connectivity in specific motor-related regions, which may reflect a compensatory role of motor deficits in PD patients.