Prediction errors explain mismatch signals of neurons in the medial prefrontal cortex

According to predictive coding theory, perception emerges through the interplay of neural circuits that generate top-down predictions about environmental statistical regularities and those that generate bottom-up error signals to sensory deviations. Prediction error signals are hierarchically organized from subcortical structures to the auditory cortex. Beyond the auditory cortex, the prefrontal cortices integrate error signals to update prediction models. Here, we recorded neuronal activity in the medial prefrontal cortex of the anesthetized rat while presenting oddball and control stimulus sequences, designed to separate prediction errors from repetition suppression effects of mismatch responses. Robust mismatch signals were mostly due to prediction errors. The encoding of a regularity representation and the repetition suppression effect over the course of repeated stimuli were fast. Medial prefrontal cells encode stronger prediction errors than lower levels in the auditory hierarchy. These neurons may, therefore, represent the neuronal basis of a fundamental mechanism of hierarchical inference.