title: Impulsive choice, alcohol consumption, and pre-exposure to delayed rewards: II. Potential mechanisms.
abstract: In a prior study (Stein et al., 2013), we reported that rats pre-exposed to delayed rewards made fewer impulsive choices, but consumed more alcohol (12% wt/vol), than rats pre-exposed to immediate rewards. To understand the mechanisms that produced these findings, we again pre-exposed rats to either delayed (17.5 s; n=32) or immediate (n=30) rewards. In posttests, delay-exposed rats made significantly fewer impulsive choices at 15- and 30-s delays to a larger, later food reward than the immediacy-exposed comparison group. Behavior in an open-field test provided little evidence of differential stress exposure between groups. Further, consumption of either 12% alcohol or isocaloric sucrose in subsequent tests did not differ between groups. Because Stein et al. introduced alcohol concentration gradually (3-12%), we speculate that their group differences in 12% alcohol consumption were not determined by alcohol's pharmacological effects, but by another variable (e.g., taste) that was preserved as an artifact from lower concentrations. We conclude that pre-exposure to delayed rewards generalizes beyond the pre-exposure delay; however, this same experimental variable does not robustly influence alcohol consumption.
authors.affiliation: Utah State University.
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Stein
authors.forename: C Renee
authors.initials: CR
authors.lastname: Renda
authors.forename: Jay E
authors.initials: JE
authors.lastname: Hinnenkamp
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Madden
mesh_terms: D000428:Alcohol Drinking / Q000523:psychology*; D000818:Animals; D003216:Conditioning, Operant; D065786:Delay Discounting; D007175:Impulsive Behavior; D008297:Male; D051381:Rats; D020318:Rats, Long-Evans; D011930:Reaction Time; D012201:Reward
keywords: alcohol self-administration; delay discounting; impulsive choice; lever press, rat; open field; sucrose self-administration