24 controls (CON, N=7 scanned twice), 51 PD patients (N=10 scanned twice), and 43 subjects with RBD (confirmed by video polysomnography) without PD (N=9 scanned twice) underwent MRI scanning (3T Philips) including a high resolution T1-weighted anatomical volume and separate eyes open and eyes closed resting state fMRI runs. Using AFNI, the fMRI volumes were motion corrected and aligned to the T1 volume. The mean resting state global signal was extracted from each eyes open and eyes closed run after motion-censoring (0.3 mm threshold) and regression of signal from ventricles and white matter. A single global signal value, defined as the standard deviation of the voxelwise signal across time averaged across all brain voxels, was computed for each eyes closed and eyes open run of each subject. The difference in open global signal was compared within each group of control, PD, and RBD subjects using a 2-tailed paired-test.