Functionally Distinct Dopamine Signals in Nucleus Accumbens Core and Shell in the Freely Moving Rat.

Orchestrated signaling from mesolimbic dopamine (DA) neurons is important for initiating appropriate behavior in response to salient stimuli. Thus, subpopulations of mesolimbic DA neurons show different in vitro properties and synaptic inputs depending on their specific projections to the core and shell subterritories of the nucleus accumbens (NAc). However, the functional consequence of these differences is unknown. Here we analyze and model DA dynamics in different areas of the NAc to establish the real-time DA signal. In freely behaving animals, we find that the DA signal from mesencephalic neurons projecting to the NAc shell is dominated by synchronized bursts and pauses, whereas signaling is uniform for core-projecting neurons; this difference is amplified by cocaine.