Subcortical control of dopamine neurons: the good, the bad and the unexpected.

The function of the phasic dopamine signal, seen in response to salient and rewarding stimuli, has been heavily debated. The reward prediction error hypothesis has been criticised for the suggestion that such a complex signal could be derived at short latencies, relying only on subcortical inputs. However, as more has been learnt about the nature of the subcortical inputs, we are led to challenge this criticism. Here we suggest that the subcortical inputs can indeed support complex calculations and that it would be unwise to underestimate their processing capabilities. Whilst our analysis cannot differentiate between the reward prediction error hypothesis and its opponents, it does suggest that the initial argument against a prediction error is incorrect.