Behavior in mice subjected to a Token Slot-machine: effect of Unpredictable Chronic Mild Stress

Several studies have succeeded in teaching animals (primates, pigeons, rats, but not mice) the value of tokens by having them executing a task using a vending-machine apparatus, where in order to receive the primary reinforcement (food), the animals had to perform a specific action that allowed them to obtain the secondary reinforcement (tokens: metal balls). We tried to assess this kind of behavior in mice that had previously been trained to use some tokens, with the aim of rewarding them not with food, but with other tokens, as a result of a token economy task. We found that mice exhibit economic behavior. Further on, our research tried to investigate the effect of stress on their operant decision-making. Therefore, the mice were divided into two groups: a Control group (n=10) and a group subjected to an Unpredictable Chronic Mild Stress (UCMS) treatment (n=8). We found that chronic stress increases some aspects of sub-optimal economic activity. Summary statement We designed an original model enabling to assess behavior in mice that had previously been trained to use some tokens, with the aim of rewarding them not with food, but with other tokens. Further on, our research investigated the effect of stress on their operant decision-making.