within this dopamine projection system are highly complex neuroanatomical ‘loops’ involving distinct cortical and subcortical structures (Haber et al., 2000; Everitt et al., 2008), as well as direct connections between the core and shell (van Dongen et al., 2005). Indeed, it has been postulated that the shell may modulate activity in the core through these circuit connections (Haber et al., 2000; Luscher & Bellone, 2008). Consistent with different anatomical inputs, our voltammetric measurements reveal that dopamine neurotransmission clearly operates on different timescales within the core and shell during the same goal-directed behavior.
