Causal evidence supporting the proposal that dopamine transients function as temporal difference prediction errors

Reward-evoked dopamine transients are well-established as prediction errors. However the central tenet of temporal difference accounts – that similar transients evoked by reward-predictive cues also function as errors – remains untested. Here we addressed this by showing that optogenetically-shunting dopamine activity at the start of a reward-predicting cue prevents second-order conditioning without affecting blocking. These results indicate that cue-evoked transients function as temporal-difference prediction errors rather than reward predictions.