EIF2AK3 and substance dependence: Valjent et al. (2004) hypothesized that a strong activation of pERK across all three extended amygdala regions distinguishes drugs most likely to be abused from other psychoactive substances that are not considered to produce addiction (e.g., antidepressants, antipsychotics), in accordance with the suggested central role of these regions in dependence (Koob et al., 2014).