II. Magnetic Resonance Imaging (MRI) The first 20 subjects recruited into each group will be scanned using a 3T scanner (Philips Achieva 3-Tesla Quasar). A T1-weighted, MPRAGE sequence (TE=3.2ms, TR=7.5ms, flip angle=7°, FOV 240mm×240 mm) of 155 consecutive slices will be acquired at sagittal view with a voxel size of 1mm×1mm×1 mm. A T2*-weighted EPI sequence will be used for functional magnetic resonance (fMRI) resting (TR/TE=2000/32ms, 32 slices) with a voxel size of 3x3x4mm.