Investigating Factors Underlying the Ability of Reward-Paired Cues to Function as Conditioned Reinforcers

Environmental stimuli paired with drugs-of-abuse can motivate drug use and increase the risk of relapse in abstinent individuals. These reward-paired stimuli can control behavior due in part to their ability to function as conditioned reinforcers (CRfs). In this thesis, I investigated factors underlying the ability of reward-paired stimuli to function as CRfs using the acquisition-of-a-new-response task. In Chapter 2, I examined the effects of reducing the reward value of saccharin on responding for a saccharin-paired CRf. Results showed that responding was not altered by saccharin devaluation. This raised the question of how drug-associated stimuli motivate drug use if they do so in a manner that is divorced from the value of the drug. One limitation of this chapter is that a non-drug reinforcer was used. Thus, in Chapter 3, I examined the effects of reducing the reward value of the drug reinforcer alcohol on responding for an alcohol-paired CRf. These studies found that responding was not altered by alcohol devaluation. Like drug-paired stimuli, stress increases vulnerability to drug use and relapse. In Chapter 4, I explored the effects of the pharmacological stressors, yohimbine and U50,488, on responding for an alcohol- or a sucrose-paired CRf. Yohimbine, but not U50,488, enhanced responding irrespective of the nature of the reward used. Some independent evidence also showed that yohimbine enhanced responding for sensory stimuli (e.g. light and tone) that had not been paired with reward. In Chapter 5, I revisted the question of whether the pairing between the stimulus and reward is important for the stimulus to function as CRf. This was done by examining the effects of manipulating the stimulus-reward association on responding. These studies found that the stimulus-reward association is important. However, the stimulus appeared to have intrinsic properties that facilitated responding. Taken together, these findings suggest that reward-paired stimuli acting as CRfs guide behavior in a manner that is independent of the value of the reward. They also substantiate a role for the intrinsic reinforcing properties of these stimuli in facilitating responding for apparent conditioned reinforcement.

Department dc:contributor.department

Psychology

Year dc:date.issued

2024

Author dc:creator

• Tabbara, Rayane

Advisor dc:contributor.advisor

• Fletcher, Paul

• Alcohol
• Conditioned reinforcement
• Cues
• Rats
• Saccharin
• Sucrose

Handle dc:identifier.uri

http://hdl.handle.net/1807/138127

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/138127