Gray’s (e.g., Gray 1994) influential theory proposes that there are two major neurobehavioral systems that underlie behavior: the behavioral activation system (BAS), which responds to signals of reward, and the behavioral inhibition system (BIS), which is sensitive to cues for punishment. Although BAS and BIS differ conceptually and empirically from E/PE and N/NE, their relations with depression are thought to be similar. Thus, it has been hypothesized that depression is associated with reduced BAS and/or heightened BIS sensitivity (Depue & Iacono 1989, Gray 1994). Although much of this work has focused on bipolar disorder (e.g., Alloy et al. 2008, Johnson et al. 2008), several recent studies have examined self-report measures of BAS and BIS sensitivity in MDD. Consistent with Gray’s model, compared with healthy controls, currently depressed patients report lower levels of BAS and higher levels of BIS, and patients with a past history of MDD report lower levels of BAS (Pinto-Meza et al. 2006). In addition, lower BAS sensitivity, but not higher BIS sensitivity, is associated with a poorer course of MDD (e.g., Kasch et al. 2002, McFarland et al. 2006), suggesting that BAS may have a pathoplastic effect on depression.
