Figure 4.

Extinction, reextinction, and test data for experiment 2A. A, For the initial extinction session (drug-free) at 17 d of age, all groups exhibited substantial levels of freezing in the first minute of extinction that decreased substantially by the last minute. B, For reextinction, group saline exhibited substantial levels of freezing in the first minute of extinction that decreased substantially by the last minute, whereas group bupivacaine exhibited very low levels of freezing throughout. Group control did not receive any CS presentations and were exposed to the context only. C, Temporary inactivation of the amygdala disrupted reextinction in rats that were extinguished at 17 d of age and then reextinguished at 20 d of age, as shown by high levels of freezing in groups bupivacaine and control compared with group saline. This result indicates that reextinction is amygdala dependent in the 17-d-old rat.