title: The effects of amphetamine exposure on outcome-selective Pavlovian-instrumental transfer in rats.
abstract: BACKGROUND
  Repeated exposure to psychostimulants alters behavioral responses to reward-related cues; however, the motivational underpinnings of this effect have not been fully characterized.
  
  
  OBJECTIVE
  The following study was designed to examine how amphetamine sensitization affects performance in rats on a series of Pavlovian and operant tasks that distinguish between general-incentive and outcome-selective forms of conditioned responses.
  
  
  METHODS
  Adult male rats underwent Pavlovian and instrumental training for food pellet rewards. Following training, rats were sensitized to D-amphetamine (2 mg/kg for 7 days). Rats were subsequently tested on an outcome-selective Pavlovian-instrumental transfer (PIT) task, an outcome-reinstatement task, and an outcome devaluation task. Additionally, in a separate experiment, PIT was assessed in amphetamine-sensitized and control rats using a Pavlovian backward-conditioned stimulus.
  
  
  RESULTS
  Repeated amphetamine exposure sensitized locomotor activity to acute amphetamine challenge. Amphetamine altered responses to CS presentations by increasing conditioned approach. During tests of PIT, amphetamine-treated rats showed no outcome-selectivity in their responding, responding to a CS whether or not it shared a common outcome with the instrumental response. No effect of amphetamine sensitization was observed on tests of outcome-selective reinstatement by outcome delivery or action selection based on outcome value. Amphetamine-sensitized rats showed impaired outcome-selective PIT to a backward CS but were unaltered in conditioned approach.
  
  
  CONCLUSIONS
  Amphetamine sensitization prevents outcome-selective responding during PIT, which is dissociable from amphetamine's effects on conditioned approach. These data suggest fundamental alterations in how stimuli motivate action in addiction.
authors.affiliation: Department of Psychology, Rutgers University, 101 Warren Street, 301 Smith Hall, Newark, NJ 07102, USA. shiflett@psychology.rutgers.edu
authors.forename: Michael W
authors.initials: MW
authors.lastname: Shiflett
mesh_terms: D000161:Acoustic Stimulation; D000661:Amphetamine / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D000697:Central Nervous System Stimulants / Q000008:administration & dosage / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects*; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D020318:Rats, Long-Evans; D012201:Reward; D014163:Transfer, Psychology / Q000187:drug effects*
chemical_list: D000697:Central Nervous System Stimulants; D000661:Amphetamine