Microcircuits in nucleus accumbens' shell and core involved in cognition and reward

Nucleus accumbens subserves numerous adaptive and goal-directed behaviors. The anatomical substrates for such are the medium spiny projection neurons, at least four different subtypes of local circuit neurons, and inputs from limbic cortical centers and brainstem monoamines. In this review, we show how microcircuits in two parts of the nucleus-the core and caudomedial shel l or septal pole-differ subtly in their connections yet permit quite differ ent behaviors. We further show how small differences in synaptic wiring, es pecially in relation to the local circuit neurons, can facilitate or suppre ss behavioral activity. Finally, we consider some important organizational principles that underlie cognitive, emotional, and rewarding behaviors.