Although regionally selective (thalamic nuclei, prefrontal, anterior cingulate, temporal, and occipital cortices) cerebral hypoperfusion abnormalities in MDD have traditionally been attributed to depressed mood states and reduced neuronal activity [87-91][208], these findings may also be related to eNOS uncoupling [65,113,114,218] (Figure 2). Here, NOS3 is linked to major depressive disorder.