Fig. 4

The food picture stimulation paradigm during fMRI. The food-cue fMRI task runs 7 min 42 s for each participant. In the beginning of the paradigm, a 12-s pre-fixation “+” appears in the center of the screen to keep the participant’s attention. After the task is completed, a post-fixation “+” appears for 12 s to end the task. A total of 16 blocks (8 high- and 8 low-fat food blocks) will be programmed. In each block, six cue high-fat food pictures or low-fat food pictures will be presented pseudo-randomly. Each picture lasts for 2 s with 1-s interval. Each block costs 17 s, with 12-s interval to the next block. In the end of each block, subjects will be asked to rate on an 11-point Likert scale for 10s. When the rating is completed, the screen will become blank for 2 s and then a new block would begin to appear