LHB and major depressive disorder: The lateral habenula (LHB) has been implicated in the pathophysiology of psychiatric disorders such as Major Depressive Disorder (MDD) (Lawson et al., 2017; Sartorius et al., 2010; Yang et al., 2018a; Zhang et al., 2019), with rodent studies highlighting the LHB in mediating the anti-depressive effect of ketamine (Yang et al., 2018b).