Examples of global signal time series computed after (1) minimal preprocessing (MinProc, blue), (2) MinProc plus removal of low-frequency (Leg: Legendre polynomial) and motion-related (Mo) nuisance terms (Leg+Mo; green), (3) MinProc plus removal of low-frequency, motion-related, and physiological (Phys) nuisance terms (Leg+Mo+Phys; red), and (3) MinProc plus removal of low-frequency, motion-related, physiological, and white matter and cerebral spinal fluid (WM/CSF) nuisance terms (Leg+Mo+Phys+WM/CSF; cyan). WM and CSF regions were defined using partial volume thresholds of 0.99 for each tissue type and morphological erosion of two voxels in each direction to minimize partial voluming with gray matter. Additional details about the processing are provided in (Wong et al., 2013).