Figure 1.

Cortico-striatal circuits involved in instrumental conditioning. (A) Evaluative learning processes, shown in red, are mediated by bilateral connections between the medial orbitofrontal cortex (mOFC) and basolateral amygdala (BLA), which are relayed to the anterior caudate nucleus (aCN). Contingency learning processes, shown in green, are thought to occur in the medial prefrontal cortex (mPFC) and are relayed to the aCN to mediate control of action selection. Reward information is also relayed to the nucleus accumbens (NAc) to provide motivational drive for the performance of instrumental behaviors. The dlPFC and dorsal anterior cingulate cortex (dACC) play a role in comparing action values and can exert a modulatory influence over circuits involving prefrontal and aCN activity. Together, the contingency and evaluative circuits allow for the acquisition of goal-directed behaviors. (B) Stimulus-response associations, or habits, are mediated by projections from premotor (PM) and sensorimotor cortices (SM) to the posterior putamen (Pu). (C) The lateral orbitofrontal cortex (lOFC) and the BLA encode the value assigned to reward predictive stimuli, which the NAc uses to mediate instrumental performance. Mid-brain dopamine modulates plasticity in the dorsal striatum, and is associated with motivational processes in the ventral striatum. The balance between striatal output to the direct (D1) and indirect (D2) pathways serves to promote or inhibit behavior, respectively.