Contribution of the medial prefrontal cortex to performance on the Traveling Salesperson Problem in rats

Cognitive impairments, including memory loss, disrupted spatial navigation, and poor executive function, are devastating features of many neurological conditions. Effective research into the causes and treatments of such disorders requires knowledge of the neurological mechanisms that underlie these cognitive processes. Our lab used a naturalistic spatial foraging task, known as the Traveling Salesperson Problem (TSP), to examine these processes in rodents. Previous studies from our lab have found that rats with hippocampal lesions or medial entorhinal cortex lesions were impaired on measures of spatial memory in the TSP task, but neither group showed impairments in measures of spatial decision-making. Given that the medial prefrontal cortex (mPFC) is typically involved in decision-making and receives projections from the hippocampus and medial entorhinal cortex, our lab investigated the effect of mPFC lesions on both male and female rat performance on the TSP. Our study found mild effects of mPFC lesions on TSP performance, evident as an interaction between mPFC lesions and sex, with route selection impairment correlating with mPFC lesion extent in males, but not females. These findings implicate the mPFC in spatial decision-making, particularly in male rats, highlighting the importance of considering sex as a biological variable in animal model research.