The role of medial prefrontal cortex in uncertainty-based decision making in rats

The prefrontal cortex plays a crucial role in decision making in humans with a certain degree of functional specialisation of the prefrontal subregions. The current state of the art implies that the lateral, ventral and medial areas of the prefrontal cortex might encode different aspects of the decision process, namely: representing various states of the environment, predicting the different outcomes of alternative choices and updating the desirability of alternative actions, respectively. Additionally, the dorsolateral cortex is believed to be involved in risk-based decision making. The medial prefrontal cortex in rats and the anterior cingulate cortex and dorsolateral prefrontal cortex in humans seem to share some functional and anatomical features. To shed further light on how specific parts of the prefrontal cortex contribute to reward-based decision making and processing of risk we have recorded the activity of cells in the medial prefrontal cortex in rats while performing a risk-based decision task. For this the rat chooses between a safe arm with a fixed reward and a risky arm where it gets a bigger reward with different probabilities across different blocks. Using a reinforcement learning model to model the behaviour of the rat, we observed cells that are linked to choice and outcome value, othercells that might be involved in the animals’ internal representation of the reward or the probability of positive outcome related to each choice. Furthermore we investigated how the uncertainty of the rewards reflects in the activity of cells. Overall, our data indicate that different aspects of the behavioural task are supported by divers activity patterns of prefrontal neurons.