Joint effect of amobarbital and response prevention of CAR extinction

The purpose of this study was to extend previous findings of enhanced CAR extinction with response prevention by demonstrating that extinction may be further facilitated by amobarbital treatment during response prevention. Ss administered amobarbital during CAR prevention did not differ significantly from the control Ss in extinction performance. Extinction was not facilitated by amobarbital when administered during CAR prevention.

Magnesium pemoline: activation of extinction responding after continuous reinforcement

Magnesium pemoline prolongs performance in extinction following continuous reinforcement although not affecting prior acquisition of food-reinforced lever pressing. 8 Ss were given magnesium pemoline and 8 a placebo. 1 wk. later Ss were extinguished, 8 on magnesium pemoline and 8 on placebo. It was found that, although magnesium pemoline had no effect on acquisition, it did significantly prolong extinction.

Conditioned suppression by a stimulus associated with nalorphine in morphine-dependent monkeys

Three rhesus monkeys, physically dependent on morphine, were trained to press a lever for food on a fixed ratio of 10 responses. A tone, initially a neutral stimulus, was aperiodically presented every third or fourth session, 5 min before and after the intravenous injection of nalorphine, a morphine antagonist which produces an immediate withdrawal syndrome in morphine-dependent monkeys. After several sessions, conditioned suppression of food-lever response rate was observed. Conditioned bradycardia, emesis, and excessive salivation also occurred. In 40 to 45 sessions the conditioned suppression of food-lever response rate and the conditioned autonomic changes were extinguished by presenting pairings of a tone and saline injection. The monkeys were then reconditioned by presenting the tone aperiodically, every third or fourth session, 5 min before and after the intravenous injection of nalorphine. Results were similar to the initial conditioning sessions. Two rhesus monkeys not dependent on morphine were stabilized on a food schedule similar to that used for the first three monkeys. These monkeys showed no change in food-lever response rate during or after nalorphine injections.