Altered resting-state functional connectivity of the dentate nucleus in Parkinson's disease

We used functional magnetic resonance imaging (fMRI) to measure functional connectivity of the dentate nucleus (DN) between patients with Parkinson's disease (PD) and normal controls who were studied in a resting state. Images were acquired in 18 PD patients and in age- and sex-matched normal controls. Connectivity of the bilateral DN was calculated and compared between patients and controls, connectivity of the bilateral DN within the cerebellum was compared between rigidity and bradykinesia-dominant patients (PDAR) and tremor-dominant patients (PDT), and correlation analysis was performed between the connectivity strength and behavioral measures within the cerebellum. Some regions in the cerebellum showed enhanced connectivity with the bilateral DN in PD patients, and decreased connectivity of the DN with the bilateral cerebellar posterior lobe was observed in PDT as compared to PDAR. A set of regions consistent with the default mode network showed disrupted connectivity with the DN. Decreased connectivity between the inferior parietal lobule and the DN was also observed in PD patients. Additional analyses did not show any significant correlations between functional connectivity within the cerebellum and Unified Parkinson's Disease Rating Scale-III scores. Our findings suggest that connectivity of the DN in the resting state is disrupted in PD, and there may be a compensatory cerebellar connectivity mechanism in the resting state in PD. Further study of the cerebellum may clarify the pathophysiology of PD.