The effect of two phenothiazines and a barbiturate on extinction-induced rate increase of a free operant.

Abstract
Rats were first trained to bar press for water reward. Then, after injection of 1 of 3 doses of either phenobarbital, thioridazine, or chlorpromazine, each animal received a 10-min. session with regular reinforcement, followed by extinction. The extinction inflection ratio (increase in response early in extinction) bore an inverse relation to dose, but was equivalent for all drugs. However phenobarbital produced greater ataxia than did the phenothiazines. (PsycINFO Database Record (c) 2006 APA, all rights reserved)