Fig. 7.

Influence of changing the time of reward delivery in the Pavlovian conditioning procedure in one tonically active neuron. Same conventions as in Figure 3. The neuron was first tested with the usual interval of 1 sec between the visual signal and reward. Then, the neuron was tested with the 2 sec delay. Delivering the liquid at the end of the well practiced 1 sec interval after the visual signal did not elicit a reward response, although such a response appeared when liquid delivery was delayed. Note that no change in firing rate was detectable at the usual time of reward delivery, i.e., 1 sec after the visual signal, when the event occurred later than expected.