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Aims The aim of this study was to investigate the involvement of the ventral intermediate nucleus of thalamus (Vim) in the tremor- and akinetic-/rigid-related networks in Parkinson's disease ( PD). Methods Tremor-dominant ( TD) and akinetic-/rigid-dominant ( ARD) PD patients were recruited and scanned by resting-state functional MRI. Functional connectivity from the Vim nucleus was analyzed. Results In the TD patients, the Vim nucleus exhibited increased connectivity with the cerebellum/dentate nucleus, primary motor cortex (M1), supplementary motor area ( SMA), premotor cortex, thalamus, globus pallidus, putamen, and parietal cortex compared with the controls, while the connections between the Vim nucleus and M1 and cerebellum/dentate nucleus had positive correlations with the tremor scores. In the ARD patients, the Vim nucleus only showed enhanced connectivity with the globus pallidus and limbic lobe compared with the controls, and no connectivity showed correlation against the akinetic-rigidity scores. TD patients had increased connectivity with the Vim nucleus in the cerebellum, M1, SMA, thalamus, globus pallidus, putamen, and parietal cortex compared with ARD patients. Conclusions This study demonstrates that the Vim nucleus has an important role in the tremor-related network, but not in the akinetic-/rigid-related network. Our finding is helpful to explain the selective effect of Vim deep brain stimulation in PD. [ABSTRACT FROM AUTHOR]

Aims Postural instability/gait difficulty ( PIGD) and tremor-dominant ( TD) subtypes of Parkinson's disease ( PD) show different clinical manifestations; however, their underlying neural substrates remain incompletely understood. This study aimed at investigating the subtype-specific patterns of spontaneous brain activity in PD. Methods Thirty-one patients with PD (12 TD/19 PIGD) and 22 healthy gender- and age-matched controls were recruited. Resting-state functional magnetic resonance imaging data were collected, and amplitude of low-frequency fluctuations ( ALFF) was measured. Voxelwise one-way analysis of covariance and post hoc analyses of ALFF were performed among the three groups, with age and gender as covariates (levodopa daily dosage and gray matter volume as additional covariates for validation analysis). Correlations of clinical variables (e.g., disease duration and PIGD/tremor subscale score) with ALFF values were examined. Results Compared with controls, patients with TD exhibited higher ALFF in the right cerebellar posterior lobe and patients with PIGD exhibited lower ALFF in the bilateral putamen and cerebellar posterior lobe, and higher values primarily in several cortical areas including the inferior and superior temporal gyrus, superior frontal, and parietal gyrus. Compared with patients with PIGD, patients with TD had higher ALFF in the bilateral putamen and the cerebellar posterior lobe, as well as lower ALFF in the bilateral temporal gyrus and the left superior parietal lobule. In all patients, ALFF in the bilateral cerebellar posterior lobe positively correlated with tremor score and ALFF in the bilateral putamen negatively correlated with PIGD score. Conclusion Different patterns of spontaneous neural activity in the cerebellum and putamen may underlie the neural substrate of PD motor subtypes. [ABSTRACT FROM AUTHOR]