(MRI) (Kempton et al., 2008). Meta-analysis of whole-brain diffusion tensor imaging (DTI) studies demonstrated decreased fractional anisotropy (FA) affecting the right hemisphere WM near the parahippocampal gyrus and cingulate cortex (Vederine et al., 2011). Because signaling among brain regions is dependent on WM tracts, these findings suggest that functional measures of neurotransmission and connectivity would also be affected. Consistent with this prediction, a growing number of imaging studies provide evidences of altered connectivity between brain regions in BD (Calhoun et al., 2011; Frangou, 2011; Houenou et al., 2012). Moreover, there is increasing consensus for decreased connectivity among ventral prefrontal and limbic regions that may reflect a key deficit in BD (Anticevic et al., 2013; Strakowski et al., 2012).
