title: Post-training amphetamine administration enhances memory consolidation in appetitive Pavlovian conditioning: Implications for drug addiction.
abstract: It has been suggested that some of the addictive potential of psychostimulant drugs of abuse such as amphetamine may result from their ability to enhance memory for drug-related experiences through actions on memory consolidation. This experiment examined whether amphetamine can specifically enhance consolidation of memory for a Pavlovian association between a neutral conditioned stimulus (CS-a light) and a rewarding unconditioned stimulus (US-food), as Pavlovian conditioning of this sort plays a major role in drug addiction. Male Long-Evans rats were given six training sessions consisting of 8 CS presentations followed by delivery of the food into a recessed food cup. After the 1st, 3rd, and 5th session, rats received subcutaneous injections of amphetamine (1.0 or 2.0 mg/kg) or saline vehicle immediately following training. Conditioned responding was assessed using the percentage of time rats spent in the food cup during the CS relative to a pre-CS baseline period. Both amphetamine-treated groups showed significantly more selective conditioned responding than saline controls. In a control experiment, there were no differences among groups given saline, 1.0 or 2.0 mg/kg amphetamine 2 h post-training, suggesting that immediate post-training amphetamine enhanced performance specifically through actions on memory consolidation rather than through non-mnemonic processes. This procedure modeled Pavlovian learning involved in drug addiction, in which the emotional valence of a drug reward is transferred to neutral drug-predictive stimuli such as drug paraphernalia. These data suggest that amphetamine may contribute to its addictive potential through actions specifically on memory consolidation.
authors.affiliation: Department of Psychology, Texas A&M University, College Station, TX 77843-4235, USA.
authors.forename: Nicholas W
authors.initials: NW
authors.lastname: Simon
authors.forename: Barry
authors.initials: B
authors.lastname: Setlow
mesh_terms: D000661:Amphetamine / Q000008:administration & dosage*; D000704:Analysis of Variance; D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects / Q000502:physiology; D001245:Association Learning / Q000187:drug effects* / Q000502:physiology; D000697:Central Nervous System Stimulants / Q000008:administration & dosage*; D003214:Conditioning, Classical / Q000187:drug effects* / Q000502:physiology; D004334:Drug Administration Schedule; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D011897:Random Allocation; D051381:Rats; D020318:Rats, Long-Evans; D012054:Reinforcement, Psychology; D012153:Retention, Psychology / Q000187:drug effects* / Q000502:physiology; D018709:Statistics, Nonparametric; D019966:Substance-Related Disorders / Q000503:physiopathology / Q000523:psychology*
chemical_list: D000697:Central Nervous System Stimulants; D000661:Amphetamine