Experimental design of monetary incentive delay task

Supplementary Fig. S1 shows a procedure of the monetary incentive delay task. Five conditions composed of the following win/loss contingencies: −$1.0, −$0.25, $0, + $0.25, + $1.0, were applied in the task. One session consisted of 75 trials (15 trials for each of five conditions) and two sessions were performed. Before the experimental session, a practice session with 25 trials (5 for each condition) was performed in the scanner. The response time during the practice session was used to adjust the target duration. The target duration was set for a hit rate around 66%. The target duration was also adjusted during the experimental session by reducing one frame (1/75 s) after two consecutive hits and increasing one frame after one failure to keep the hit rate around 66% throughout the session.