“…For example, evidence suggests that cocaine use appears to recruit more tightly constrained circuits including canonical reward circuitry and the default mode network (Goldstein et al, 2009; Elton et al, 2015; Kaag et al, 2018) whereas activation associated with heroin use appears to be more widespread and more likely to include regions supporting motor function (Hassani-Abharian et al, 2015; Li et al, 2012; Li et al, 2013). Further, prior meta-analyses studying users of these substances have largely utilized broad inclusion criteria, examined users of a single drug (rather than a direct comparison across substances) or examined outcomes other than functional activation (e.g., gray matter, structural differences); these differences in methodology impact the ability to isolate activation patterns solely in response to reactivity to drug cues to neutral cues between users of these difference substances (Hall et al, 2015, Wollman et al, 2015; Wollman et al, 2017; Devoto et al, 2020; Suchting et al, 2020; Dang et al, 2022; Pollard et al, 2023). Thus, in order to completely understand differential activation patterns across these two substance s a more stringent synthesis regarding the neural circuits implicated in cocaine and heroin usage is needed.…”