Figure 6.

Peri-event histograms reveal the dip in DA activity which occurs in response to omitted reward after training. (A) With the US still present, the average neuronal response to the final 10 training presentations of the CS–US pairing demonstrates an STR-mediated suppression of DA activity to near baseline (c.f. Figure 4). (B) Presentation of the CS alone in 10 trials immediately after training elicits the same STR response as in previous trials, but this now leads to a below-baseline suppression of DA activity at precisely the time of the expected (but omitted) US.