Imaging studies, however, support the notion that substance abusers, regardless of what drugs they abuse, exhibit reduced error-related ACC activity. For example studies have found decreased error-related ACC activity in individuals who use marijuana (Gruber & Yurgelun-Todd, 2005), opiates (Forman et al., 2004), cocaine (Goldstein et al., 2007; Kaufman, Ross, Stein, & Garavan, 2003) and methamphetamine (London et al., 2005). Overall, these results suggest that individuals with substance abuse may have a decrement in error-processing, although more ERP studies are required to examine this with specific regard to the ERN.
