Effects of phencyclidine and ketamine on punished and unpunished responding by pigeons

Pigeons responded under a multiple fixed-interval fixed-interval schedule of food presentation in which responding in one component was suppressed by presentation of electric shock (punishment). High doses of pentobarbital, ketamine and phencyclidine produced decreases in rates of unpunished responding. At least two doses of each drug produced mean rates of punished responding greater than 200% of control rates. All three during disrupted normal patterning of both unpunished and punished fixed-interval responding. These results demonstrate that phencyclidine and ketamine have activity qualitatively similar to that of pentobarbital on schedule-controlled responding suppressed by electric shock presentation.