Allegra system

All structural and functional images were collected using a 3T Siemens Allegra system (Siemens, Erlangen, Germany). Each participant underwent a T1-weighted structural MRI, a task-free fMRI and a DTI scan in the same session. High-resolution T1-weighted structural MRI was acquired using MPRAGE (magnetization-prepared rapid gradient echo) sequence (192 continuous sagittal slices, TR/TE/TI = 2,300/1.9/900 ms, flip angle = 9°, FOV = 256 × 256 mm², matrix = 56 × 256, isotropic voxel size = 1.0 × 1.0 × 1.0 mm³, bandwidth = 240 Hz/pixel). DTI was obtained using a single-shot, echo-planar imaging (EPI) sequence (61 non-collinear diffusion gradient directions at b = 1,150 s/mm², seven volumes of b = 0 s/mm², TR/TE = 6,800/85 ms, FOV = 256 × 256 mm², matrix = 84 × 84, 48 contiguous slices, and slice thickness = 3.0 mm). A 5-min task-free fMRI were acquired using a single-shot EPI sequence (TR/TE = 2,300/25 ms, flip angle = 90°, FOV = 192 × 192 mm, matrix = 64 × 64, 48 contiguous axial slices, and voxel size = 3.0 × 3.0 × 3.0 mm³).

Magnetic resonance imaging (MRI) was performed on a 3 Tesla Allegra system (Siemens, Erlangen, Germany). A standard birdcage head coil along with foam pads was used to reduce head motion and scanner noise. High-resolution whole brain volume T1-weighted 3D anatomical data were acquired using the 3D magnetization-prepared rapid gradient echo (3D MPRAGE) sequence. The scanning parameters were: repetition time = 2530 ms; echo time = 3.5 ms; flip angle = 7°; field of view = 256 mm × 256 mm; data matrix = 256 × 256; slice thickness = 1 mm; gap = 0 mm; number of slices = 192 slices. The image resolution was 1 mm × 1 mm × 1 mm.