RATIONALE: Inability to tolerate delays to reward is an important component of impulsive behaviour, and has been suggested to reflect dysfunction of dopamine systems. OBJECTIVES: The present experiments examined the effects of signalling a delayed, large reward on rats' ability to choose it over a small, immediate reward, and on the response to amphetamine, a dopamine receptor antagonist, and a benzodiazepine. METHODS: Three groups of Lister hooded rats were tested on a two-lever discrete-trial delayed reinforcement task in which they chose one pellet delivered immediately or four pellets delivered after a delay. This delay increased from 0 to 60 s during each session. Trials began with illumination of a houselight: in the Houselight group, this remained on during the delay and feeding period. In the No Cue group, the houselight was extinguished at the moment of choice. In the Cue group, a stimulus light was illuminated during the delay. Once trained, the rats were challenged with d-amphetamine (0.3, 1.0, 1.6 mg/kg), chlordiazepoxide (1.0, 3.2, 5.6, 10 mg/kg), alpha-flupenthixol (0.125, 0.25, 0.5 mg/kg), and various behavioural manipulations. RESULTS: Subjects' choice became and remained sensitive to the delay; the cue speeded learning. Amphetamine decreased choice of the large reinforcer in the No Cue group and increased it in the Cue group. alpha-Flupenthixol and chlordiazepoxide generally decreased preference for the delayed reinforcer; flupenthixol reduced the cue's effects, but chlordiazepoxide did not interact with the cue condition. CONCLUSIONS: Signals present during a delay can enhance the ability of amphetamine to promote choice of delayed rewards.
RATIONALE: Inability to tolerate delays to reward is an important component of impulsive behaviour, and has been suggested to reflect dysfunction of dopamine systems. OBJECTIVES: The present experiments examined the effects of signalling a delayed, large reward on rats' ability to choose it over a small, immediate reward, and on the response to amphetamine, a dopamine receptor antagonist, and a benzodiazepine. METHODS: Three groups of Lister hooded rats were tested on a two-lever discrete-trial delayed reinforcement task in which they chose one pellet delivered immediately or four pellets delivered after a delay. This delay increased from 0 to 60 s during each session. Trials began with illumination of a houselight: in the Houselight group, this remained on during the delay and feeding period. In the No Cue group, the houselight was extinguished at the moment of choice. In the Cue group, a stimulus light was illuminated during the delay. Once trained, the rats were challenged with d-amphetamine (0.3, 1.0, 1.6 mg/kg), chlordiazepoxide (1.0, 3.2, 5.6, 10 mg/kg), alpha-flupenthixol (0.125, 0.25, 0.5 mg/kg), and various behavioural manipulations. RESULTS: Subjects' choice became and remained sensitive to the delay; the cue speeded learning. Amphetamine decreased choice of the large reinforcer in the No Cue group and increased it in the Cue group. alpha-Flupenthixol and chlordiazepoxide generally decreased preference for the delayed reinforcer; flupenthixol reduced the cue's effects, but chlordiazepoxide did not interact with the cue condition. CONCLUSIONS: Signals present during a delay can enhance the ability of amphetamine to promote choice of delayed rewards.
Authors: Marci R Mitchell; Colin M Vokes; Amy L Blankenship; Nicholas W Simon; Barry Setlow Journal: Psychopharmacology (Berl) Date: 2011-06-03 Impact factor: 4.530
Authors: Nicholas W Simon; Karienn S Montgomery; Blanca S Beas; Marci R Mitchell; Candi L LaSarge; Ian A Mendez; Cristina Bañuelos; Colin M Vokes; Aaron B Taylor; Rebecca P Haberman; Jennifer L Bizon; Barry Setlow Journal: J Neurosci Date: 2011-11-30 Impact factor: 6.167
Authors: Laura-Jean G Stokes; Anna Davies; Paul Lattimore; Catharine Winstanley; Robert D Rogers Journal: Philos Trans R Soc Lond B Biol Sci Date: 2019-02-18 Impact factor: 6.237