Moral cognition in males and females : an analysis of white matter tracts underlying grey matter areas related to morality

Abstract

Studies investigating moral cognition have generally focused on grey matter activations obtained from neuroimaging studies, however there is a gap in the literature investigating the white matter fibre pathways underlying these grey matter areas related to morality. For this reason, this study investigated the fibre pathways underlying the functional areas associated with moral cognition and examined whether there are any significant sex differences in fibre metrics of these pathways. In this study, these white matter fibre pathways are referred to as ‘moral connectome’. Results from the automated meta-analysis mainly show an activation in the vmPFC extending to the OFC, mPFC, dmPFC, TPJp, PCC, the bilateral TP, the bilateral MTL, the left pars opercularis of IFG, and parts of the precuneus. The moral connectome underlying these functional areas were found to be the cingulum (bilateral), forceps minor, the fornix and the extreme and external capsule. As findings about sex differences in white matter areas are inconsistent, this study further investigated sex differences in the moral connectome by performing a fixel-based analysis to compare different fibre metrics between males and females. The findings showed no significant sex differences in the fibre metrics of the moral connectome, once the results were corrected for brain volume per subject. Therefore, this study shows no evidence for sex differences in white matter over and above that explained by brain size.