ASL analysis
First, we motion-corrected and de-noised all images using the ASLtbx toolbox (Next, we calculated CBF with the following formula.Here, λ denotes the blood–brain partition coefficient for water, which we assumed to be 0.9 based on the publication of Herscovitch and RaichleThen, to obtain relative CBF values, we calculated the relative CBF dividing the subject-specific CBF-values of each voxel by the average CBF across 48 Brodmann’s areas. Finally, we normalised the CBF maps to the Montreal Neurological Image (MNI) template, provided by SPM12 (Wellcome Trust, U.K.).