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Enhanced appetitive conditioning following repeated pretreatment with d-amphetamine
1Department of Psychology, University of York, Heslington, UK.
Behavioural Pharmacology
|March 5, 1999
Summary
Repeated exposure to d-amphetamine enhances behavioral sensitization and appetitive Pavlovian conditioning in rats. This suggests changes in dopamine pathways may underlie these drug-induced adaptations in learning and behavior.
Area of Science:
- Neuroscience
- Behavioral Pharmacology
Background:
- Repeated psychomotor stimulant exposure augments behavioral responses.
- This behavioral sensitization is linked to enhanced dopamine overflow in the nucleus accumbens and amygdala.
Purpose of the Study:
- To investigate the effects of d-amphetamine-induced behavioral sensitization on Pavlovian conditioning.
- To determine if sensitization alters appetitive conditioning acquisition and reward efficacy.
Main Methods:
- Rats received daily d-amphetamine or saline for 5 days, followed by a 5-day withdrawal period.
- Behavioral sensitization was confirmed via locomotor activity.
- Pavlovian conditioning involved S+ (sucrose-paired) and S- (unpaired) stimuli, followed by an instrumental conditioning task.
Main Results:
- Sensitized rats exhibited enhanced locomotor activity after a d-amphetamine challenge.
- Sensitized animals showed significantly improved acquisition of conditioned responding to the S+ stimulus.
- No differences were observed in response to S-, during sucrose presentation, or in instrumental conditioning preference.
Conclusions:
- Prior d-amphetamine exposure selectively enhances appetitive Pavlovian conditioning acquisition.
- This enhancement occurs without affecting the conditioned reward efficacy of the associated stimulus.
- Findings suggest potential alterations in mesoamygdaloid dopamine pathways contribute to sensitization-related learning changes.