What a relief! A role for dopamine in positive (but not negative) valence.

We have long known that dopamine encodes the predictive relationship between cues and rewards. But what about relief learning? In this issue of Neuropsychopharmacology, Mayer et al. show that the same circuits encoding rewarding events also encode relief from aversive events. And this appears to be in a manner distinct from encoding of the aversive event itself. So does dopamine only contribute to learning about positive events? And are these events encoded in the same way regardless of how that positive experience came about? Not quite. Turns out, the devil is in the details.