Resting state functional magnetic resonance imaging in Parkinson's disease.

Neuroimaging advances over the past several decades have provided increased understanding of the structural and functional brain changes that occur with Parkinson's disease (PD). Examination of resting state functional magnetic resonance imaging (rs-fMRI) provides a noninvasive method that focuses on low-frequency spontaneous fluctuations in the blood-oxygenation-level-dependent signal that occurs when an individual is at rest. Several analysis methods have been developed and used to explore how PD affects resting state activity and functional connectivity, and the purpose of this review is to highlight the critical advances made thus far. Some discrepancies in the rs-fMRI and PD literature exist, and we make recommendations for consideration in future studies. The rs-fMRI technique holds promise for investigating brain changes associated with the motor and nonmotor symptoms of PD, and for revealing important variations across large-scale networks of the brain in PD.