The effects of post-acquisition-trial sodium amylobarbitone on subsequent extinction behaviour

In a one-trial-per-day runway task, previously trained rats were injected via temporary intravenous cannulae with Sodium Amylobarbitone (SA) 15 mg/kg, or saline, immediately following each of six acquisition trials, according to one of four regimes. The animals were then extinguished with no further drug or saline treatments. Those that had been consistently reinforced (CR) and consistently treated with saline extinguished faster than those that had been partially reinforced (PR) and consistently treated with saline: the brief PR schedule thus generated a typical PR extinction effect. PR animals that had received SA treatments following nonrewarded trials and saline treatments following rewarded trials extinguished faster than those that had received the opposite treatments. Post-nonreward SA treatment during acquisition thus led to a pseudo CR extinction effect, while post-reward SA treatment in acquisition led to an undistorted PR extinction effect. The results are interpreted as showing that there is a critical period occurring between some tens of seconds and a very few minutes after frustrative nonreward which is vulnerable to SA in a non-state-dependent manner, and on which frustrative nonreward's control of subsequent behaviour depends.