The NAc consists of two primary sub-regions, the core and the shell, which differ in their anatomical connections and functional properties. Each sub-region receives afferent projections from a variety of cortical and subcortical structures including the basolateral amygdala, the prefrontal cortex, and the hippocampus (Groenewegen et al., 1991; Zahm & Brog, 1992; Brog et al., 1993; Wright et al., 1996). Additionally, the core and shell receive dense dopaminergic input from the VTA (Zahm & Brog, 1992) that is believed to modulate cortical and subcortical activation of NAc neurons (Mogenson et al., 1980; Pennartz et al., 1994; Nicola et al., 2000). However, the inability of VTA electrophysiology studies to selectively record from dopamine neurons that project exclusively to the core or shell make it impossible to determine whether dopamine is differentially released across NAc subregions during behavior. In terminal regions, rapid dopamine signaling (transients) occur with the same temporal and spatial resolution as NAc cell firing relative to goal-directed behaviors for cocaine (Phillips et al., 2003b), natural rewards (Roitman et al., 2004) and ICSS (Cheer et al., 2007). Importantly, we recently
