title: Increasing food deprivation relative to baseline influences D-amphetamine dose-response gradients.
abstract: Several studies using non-pharmacological discriminative stimuli have found that stimulus control, as evident in generalization gradients, changes when motivation for (i.e., deprivation of) the relevant reinforcer is altered. Drug-discrimination studies, however, have not consistently revealed such an effect. A procedural detail that may account for the lack of a reliable effect in drug-discrimination studies is that motivation was characteristically reduced relative to the training condition in these studies. The present experiment examined how substantially increasing motivation affects D-amphetamine discrimination. Rats initially were trained to discriminate D-amphetamine (1.0 mg/kg) from vehicle (0 mg/kg) injections under 22-h food deprivation conditions. Dose-response gradients were then obtained under 22-h and 46-h deprivation levels. The ED50 was significantly higher with greater deprivation. This finding suggests that increasing motivation relative to the training condition may reduce stimulus control by drugs, while decreasing it may sharpen stimulus control.
authors.affiliation: Department of Psychology, Western Michigan University, United States.
authors.forename: Amin D
authors.initials: AD
authors.lastname: Lotfizadeh
authors.affiliation: Department of Psychology, Western Michigan University, United States.
authors.forename: Zachary J
authors.initials: ZJ
authors.lastname: Zimmermann
authors.affiliation: Department of Psychology, Western Michigan University, United States.
authors.forename: Erin E
authors.initials: EE
authors.lastname: Watkins
authors.affiliation: Department of Psychology, Western Michigan University, United States.
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Edwards
authors.affiliation: Department of Psychology, Western Michigan University, United States. Electronic address: alan.poling@wmich.edu.
authors.forename: Alan
authors.initials: A
authors.lastname: Poling
mesh_terms: D000818:Animals; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects; D003913:Dextroamphetamine / Q000494:pharmacology*; D004193:Discrimination Learning / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005508:Food Deprivation; D008297:Male; D017207:Rats, Sprague-Dawley
chemical_list: D000697:Central Nervous System Stimulants; D003913:Dextroamphetamine
keywords: Drug discrimination; Generalization gradient; Motivating operations; Motivation; Stimulus control; d-Amphetamine