2.3 Image preprocessing and analysis
2.3.1 Image preprocessing: Baseline analysis.
All of the T1-weighed MRI images were processed using the voxel-based morphometry (VBM) toolbox in SPM8 (The Wellcome Department of Imaging Neuroscience, London; http://www.fil.ion.ucl.ac.uk/spm) with the default parameters on the Matlab 7.1 platform (The Mathworks, Natick, MA, USA). Detailed processing steps of VBM have been presented previously [12,13]. Briefly, all of the MRI images were first normalized and segmented into GM, white matter and cerebrospinal fluid. Subsequently, GM images were modulated and smoothed using default parameter settings.