Figure 3.

Extinction, reextinction, and test data for experiment 2A. A, For the initial extinction session (drug-free) at 24 d of age, all groups exhibited significant levels of freezing in the first minute that decreased substantially by the last minute. There were no group differences. 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 at reextinction had no effects on reextinction, as shown by low levels of freezing in groups saline and bupivacaine compared with the nonreextinguished control group. As found previously in the adult rat, this result indicates that the amygdala is no longer involved in reextinction in 24-d-old rats.