The VBM8 toolbox was used for structural data preprocessing and to check the quality of the data. Preprocessing was done using the “estimate and run” module that performs bias correction, tissue segmentation, affine registration, normalization, and modulation. VBM8 uses a maximum posteriori method for segment tissue types. Segmented images were normalized to Montreal Neurological Institute (MNI) space using nonlinear DARTEL normalization. These quality controlled modulated images were then smoothed using a 12mm full-width at half-maximum (FWHM) isotropic Gaussian kernel.
