BEHAVIORAL AND NEURAL BIOLOGY 52, 108-115 (1989) BRIEF REPORTS A Flavor Paired with Lithium Chloride Blocks the Formation of a PentobarbitaI-Lithium Chloride Association GERARD M. MARTIN AND DENNIS V. DOYLE 1 Department of Psychology, Memorial University, Newfoundland, Canada A1B 3X9 Thirsty rats were used in order to determine whether a vinegar solution, which had been paired with an injection of lithium chloride, could block the formation of an association between a pentobarbital- and a lithium chloride-induced state. During phase 1 the rats in the blocking group had a 2.0% vinegar solution paired with an injection of 240 mg/kg of lithium chloride, during phase 2 th~se rats were reexposed to the vinegar prior to each injection of 20 mg/kg of pentobarbital and 240 mg/kg of lithium chloride, and during phase 3 these rats were given access to a novel 0.75% saccharin solution and were injected with pentobarbital after saccharin removal. Animals with this history did not form an association between the pentobarbital- and lithium chloride-induced states during phase 2 as evidenced by their refusal to consume the saccharin solution over repeated pairings of saccharin with pentobarbital during phase 3. Control groups that received forward pairings of pentobarbital and lithium chloride, in the absence of a previously conditioned vinegar solution during phase 2, formed an association between pentobarbital and lithium chloride. These findings indicate that drug states and flavors can interfere with each others' capacity to predict the occur- rence of lithium chloride. © 1989AcademicPress, Inc. The capacity of drug states to serve as Pavlovian conditional stimuli has only recently been studied (Cunningham & Linakis, 1980; Lett, 1983; Martin, 1982; Revusky, Taukulis, Parker, & Coombes, 1979a). The ab- sence of a detailed examination of the Pavlovian associations formed by drug states can be attributed to the difficulty in obtaining direct measures of such associations (but see, Taukulis, 1982). Typically pairing a drug state with some unconditional stimulus does not result in any behavioral changes in the animal's response to the drug state. Consequently, one We are very grateful to A. E. Storey and V. Grant for commenting on an earlier version of this manuscript and to B. T, Lett and S. Revusky for helpful suggestions during the execution of these experiments. This research was supported by an NSERC grant to the first author. Reprints can be obtained from Gerard M. Martin, Department of Psy- chology, Memorial University, St. John's, Newfoundland Canada A1B 3X9. 108 0163-1047/89 $3.00 Copyright @ 1989 by Academic Press, Inc. All rights of reproduction in any form reserved.