Insula lesions reduce stimulus-driven control of behavior during odor-guided decision-making and autoshaping

The insula has become a significant brain region in the study of both normal and impaired behavior and decision-making and has emerged as an important contributor to drug addiction. Consistent with this literature, in a previous study, we found that neural signals in rat insula encode anticipation and contextual global reward value during performance of an odor-guided delay/size choice task, and that these signals are disrupted by prior cocaine self-administration. Still, it is unknown if insula is critical for performance of this task under normal circumstances. Here, we sought to elucidate the functional role of these signals by lesioning the same region of anterior insula we previously recorded from. In addition to examining behavior during decision-making, we characterized behavior during autoshaping to further assess insula's role in behavior. We found insula damage resulted in reduced accuracy and faster reaction times, without affecting rats' choice of high-value reward, and that insula lesions reduced sign-tracking behavior. These results suggest that insula contributes to our odor-guided delay/size choice task via mechanisms that impact the control that environmental stimuli have on behavior.