CHOOSING BETWEEN CHOICES: SEARCHING FOR AGENCY IN THE RODENT MODEL OF HEROIN TAKING

This study was motivated by Ahmed’s (2024) observation that subjects in animal models of addiction lack agency. He describes how addiction research has tended towards volitional behavior, but has yet to sufficiently offer subjects the agency needed to model addiction. Animals have been given choices between reinforcers, but not the opportunity to change their circumstances. Methods: Rats were trained to choose between self-administered heroin or sucrose pellets in two contexts. In one context, heroin was cheap and sucrose was expensive. In the other context, the relative prices of these reinforcers were reversed. Then, rats were allowed to choose between the contexts under various conditions. Main findings: Rats frequently switched between the contexts when the cost of switching was low and obtained many of the cheap reinforcers available in each context. As the cost of switching increased, rats switched less often and increased consumption of the cheap reinforcer available in their current context. When rats could only make one choice of context per session, large individual differences were observed, with some rats preferring the cheap heroin context and others preferring the cheap sucrose context. Conclusions: This study found that when rats are given the ability to choose between choices they will take advantage of this additional level of control. The initial environmental contingencies were, however, an important determinant of heroin-taking behavior. This finding is a step towards refining animal models of addiction towards a stronger analogy to human behavior.