The role of sex on sign-tracking acquisition and outcome devaluation sensitivity in Long Evans rats

Abstract

Cues that predict rewards can trigger reward-seeking behaviors but also can, in some cases, become targets of motivation themselves. One behavioral phenomenon that captures this idea is sign-tracking in which animals, including humans, interact with reward-predictive cues even though it is not necessary to do so. Sign-tracking in rats has been studied in the domain of motivation and in how motivated behaviors can or cannot become excessive and habit-like over time. Many prior studies look at sign-tracking examine this behavior in male subjects, but there are few papers that look at this behavior in female subjects. Moreover, it is unknown where there might be sex-related variation in how flexible sign-tracking is when faced with changing reward values. Therefore, we asked if there were sex differences in the acquisition of sign-tracking behavior and if there were any sex differences in how sensitive animals were in their sign-tracking following reward devaluation. In contrast to previous reports, we found that males and females show no differences in how they acquire sign-tracking and in ultimate sign-tracking levels following training. Additionally, we found no difference in how quickly males and females learned to devalue the food reward, and we found no differences in sign-tracking levels by sex following outcome devaluation. We believe that this is primarily due to our experiment being performed in the Long Evans strain but also believe that there are many other factors contributing to differences between our study and previous work.