Snodgrass, S. H., & McMillan, D. E. (1996).
Drug discrimination under a concurrent schedule.
Journal of the Experimental Analysis of Behavior,
65, 495-512.
Three pigeons were trained to discriminate a 5.0 mg/kg dose of
pentobarbital from saline under a two-key concurrent schedule
with responding on the key associated with the presession
injection, under both stimulus conditions, producing four times
as many reinforcers as responding on the other key. This
concurrent schedule resulted in approximately 70% responding to
the higher reinforcement key under the pentobarbital stimulus and
approximately 30% responding to that key under the saline
stimulus. During testing, then, the pigeons were able to
dose-dependently emit higher (>70%) or lower (<30%) values
than were established under the control conditions. Dose -
response curves were determined for pentobarbital (twice),
methamphetamine, phencyclidine, chlordiazepoxide, and the
combination of pentobarbital and the barbiturate antagonist
bemegride. The results obtained with pentobarbital and
chlordiazepoxide showed that, as the dose increased,
pentobarbital-appropriate responding also increased.
Methamphetamine produced relatively flat dose - response curves,
whereas phencyclidine administration produced inconsistent
effects on responding. The combination of the training dose of
pentobarbital with increasing doses of bemegride produced a
decrease in pentobarbital-appropriate responding. The results
also showed that the dose - response curves for pentobarbital and
chlordiazepoxide, instead of being all or none, were graded
functions of the drug dose.
Key words: drug discrimination, concurrent schedule, matching
law, graded versus quantal dose - response curve, pentobarbital,
key peck, pigeons