entering the scanner, all participants were told to close their eyes, remain still and relaxed, and stay awake during the scanning. After the resting-state scanning, several functional activation runs were acquired with cognitive tasks (data to appear elsewhere). All participants could response to these tasks immediately after the resting-state scanning suggesting they may not asleep during the resting state. Before and after the scanning, according to the reports of a clinical psychologist, all the heroin users were ensured to be at a stable state and not intoxicated during the scanning.
