Ventral striatal lesions disrupt dopamine neuron signaling of differences in cue value caused by changes in reward timing but not number.

We recently showed that ventral striatal (VS) lesions abolished reward prediction errors that reflect changes in reward timing while leaving relatively unaffected errors that reflect changes in reward number. Here we extended those results by examining whether normal learning-related changes in firing to the reward-predictive cues in the same dopamine neurons were also disrupted by VS lesions. This analysis revealed that dopamine neurons recorded in VS-lesioned rats failed to show value-related changes in firing to the cues in timing but showed normal changes in number blocks. This effect suggests that the loss of reward-evoked error signals in the timing blocks impaired encoding of the cue value in downstream areas, which then supply these predictions to dopamine neurons at the time of cue presentation. (PsycINFO Database Record