Figure 8.

Local administration of MTEP into the IfL cortex during extinction training prevented the facilitating effects of CDPPB on extinction learning. Rats from this experiment were trained to self-administer ethanol using the ethanol pre-exposure technique (the average ethanol consumption for a 30 min session was 0.94 g/kg). A, Before extinction training, there were no differences between the two groups in ethanol self-administration (p > 0.05). B, Treatment with MTEP before each daily extinction session resulted in a significant treatment × session interaction (p = 0.011; n = 6). Post hoc analyses revealed that rats treated with MTEP had significantly more responses on the previously active lever compared with vehicle-treated rats on multiple extinction sessions. *p < 0.006. B, C, Rats treated with MTEP before CDPPB administration also required significantly more extinction sessions to reach extinction criteria compared with vehicle-treated rats (p = 0.002). D, Diagram of coronal rat brain sections showing the location of microinjector tips (dark circles) in the IfL cortex. Illustrations were adapted from the atlas of Paxinos and Watson (2005). The numbers along the left side of each section represent the distance (in millimeters of that section from bregma. E, Representative photomicrograph showing the injection site into the IfL cortex.