Typically denotes a collection of interconnected structures that signal information related to rewards (among other functions). Major pathways include the mesolimbic and mesocortical dopamine systems, both of which originate in the ventral tegmental area and connect to multiple subcortical and cortical regions. Although we continue with the common practice of employing the term “reward system,” it should be noted that its function is quite diverse (e.g., regulation of effort and resource allocation), subject to debate, and not restricted to reward per se.