The acquisition of new goal-directed actions requires the encoding of action-outcome associations. At a neural level, this encoding has been hypothesized to involve a prefronto-striatal circuit extending between the prelimbic cortex (PL) and the posterior dorsomedial striatum (pDMS); however, no research identifying this pathway with any precision has been reported. We started by mapping the prelimbic input to the dorsal and ventral striatum using a combination of retrograde and anterograde tracing with CLARITY and established that PL-pDMS projections share some overlap with projections to the nucleus accumbens core (NAc) in rats. We then tested whether each of these pathways were functionally required for goal-directed learning; we used a pathway-specific dual-virus chemogenetic approach to selectively silence pDMS-projecting or NAc-projecting PL neurons during instrumental training and tested rats for goal-directed action. We found that silencing PL-pDMS projections abolished goal-directed learning, whereas silencing PL-NAc projections left goal-directed learning intact. Finally, we used a three-virus approach to silence bilateral and contralateral pDMS-projecting PL neurons and again blocked goal-directed learning. These results establish that the acquisition of new goal-directed actions depends on the bilateral PL-pDMS pathway driven by intratelencephalic cortical neurons. The acquisition of goal-directed actions is hypothesized to be mediated by a prefronto-striatal circuit. Here, Hart et al. establish that the acquisition of such actions requires a monosynaptic, bilateral circuit involving the bilaterally projecting intratelencephalic neurons in the prelimbic cortex that target the posterior dorsomedial striatum.
Hart, G., Bradfield, L. A., Fok, S. Y., Chieng, B., & Balleine, B. W. (2018). The Bilateral Prefronto-striatal Pathway Is Necessary for Learning New Goal-Directed Actions. Current Biology, 28(14), 2218-2229.e7. https://doi.org/10.1016/j.cub.2018.05.028