2.8.1. Voxel-level associations
A block design analysis was conducted on the meth > neutral contrast in pre- and post-stimulation scanning sessions using general linear models (GLM). The functional map and computational head models were transformed to MNI space, excluding non-brain voxels. EFs were resampled to match the resolution of the functional map, resulting in final maps comprising approximately 1050624 (96 x 114 x 96) voxels. Three-dimensional voxels were vectorized, along with the different columns of a matrix for each map, where participants were stacked along the rows. Let Xi and Yi represent the column vectors across all participants for the i-th voxel from the EF and fMRI matrices. A whole-brain voxel-wise correlation was calculated between each corresponding voxel within the brain. The spatial distribution of the correlations (r-values and p-values) was then used to reconstruct the brain map. Statistical results were corrected for multiple comparisons using false discovery rate correction (FDR).