Objective: To evaluate functional connectivity of SN with basal ganglia and motor cortex in Parkinson’s disease (PD) using resting state functional MRI (RS fMRI).

Background: The clinical manifestation of neurodegenerative diseases is thought to result from disrupted functional brain networks. Parkinson’s disease is a neurodegenerative disorder characterised by progressive dopaminergic neuronal loss of SNc with further dysfunction of striatal-thalamic-cortical loops. To investigate the pattern of network dysfunction resulting from SN neurodegeneration we subsequently performed a resting state fMRI cross-sectional study of nigral functional connectivity.

Methods: Twenty-nine early stage PD subjects during medication off state and twenty-six age and sex matched healthy controls were studied with resting state (RS) fMRI. Spontaneous low-frequency (0.08-0.1 Hz) blood oxygenation level-dependent (BOLD) signal intensity fluctuations of SN were used to identify significant temporal correlations with a priori striatal and motor cortical regions. For each individual the mean SN time series were correlated with the time series of striatal nuclei and the regions of the Human Motor Area Template (HMAT). Nigral seeds were divided into more and less affected sides according to clinical motor severity as assessed with UPDRS part III.

Results: Nigral seed regions showed positive functional connectivity with thalamus, globus pallidus and putamen and was anticorrelated with sensorimotor cortex in both PD and HC groups. In contrast, additional negative connectivity was shown in premotor cortex (SMA and premotor dorsal areas) in PD group. Further decline of functional connectivity in premotor cortex were found in most affected SN when compared to the less affected. Bilateral reductions of functional connectivity in dorsolateral prefrontal, premotor and parietal superior and inferior cortices were found in PD group when compared to HC.

Conclusions: Our results demonstrate the in vivo disrupted nigral functional connectivity using RS fMRI with the striato-thalamo-cortical structures in early PD patients, in keeping with the dopaminergic neurodegeneration.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/assessing-nigral-functional-connectivity-in-parkinsons-disease-with-resting-state-functional-mri/