Methamphetamine hydrochloride (METH: 2mg/kg, IP; Sigma-Aldrich) or cocaine hydrochloride (COC: 15mg/kg, IP; in the mini-pump, the concentration was 22.5mg/ml or 11.25mg/ml; NIDA) were dissolved in sterile 0.9% saline and administered at the designated doses. In some experiments, mice also received injections (IP) of vehicle (0.9% DMSO/25% hydropropylβ-cyclodextrin; HPβCD) or racemic (+/−) Blebbistatin (blebb; Tocris). Blebb was diluted to 1mg/ml in HPβCD vehicle, and administered at the dose of 10mg/kg, as previously described [4 (link),6 (link),8 (link)]. In some experiments, vehicle (sterile saline) or the selective CRF2 antagonist Astressin-2B [AS2B, Tocris; 20 (link),21 (link),22 (link)] was infused into BLA (1ug/0.5ul/side at a rate of 0.25ul/minute) 20 minutes before conditioning, or 15 minutes after the final conditioning session. AS2B dose, rate, and times of infusions were based on previous research [23 (link)–25 (link)]. Additionally, in other experiments, vehicle (sterile saline) or the selective CRF2 agonist Urocortin 3 (UCN3, Bachem) was infused into BLA (2ug/0.66ul/side at a rate of 0.3ul/minute) 15 minutes after the final conditioning session or 20 minutes before each PM conditioning session (CS+). UCN3 dose and rate were based on previous research [26 (link)–29 (link)].