Functional images were acquired under resting-state conditions with a 3-T Siemens scanner (Erlangen, Germany) at Beijing Imaging Center for Brain Research. Participants were instructed to relax, keep their head still and eyes closed, and not think about anything systematically or fall asleep. Functional images were obtained using an echo planar imaging sequence with the following parameters: time repetition = 2000 ms; time echo = 30 ms; flip angle = 90°; field of view = 200 mm × 200 mm; 33 axial slices; slice thickness = 3.0 mm; gap = 0.6 mm; acquisition matrix = 64 × 64; in-plane resolution = 3.125 × 3.125 and 200 volumes. To aid the localization of functional data, a high-resolution, three-dimensional T1-weighted structural image was also acquired for each subject with the following parameters: 176 slices; resolution = 256 × 256; voxel size = 1 mm × 1 mm × 1 mm; time repetition = 1900 ms; time echo = 2.2 ms; flip angle = 9°.
