Differential role of the medial and lateral prefrontal cortices in fear and anxiety

In the rat, both the medial and lateral prefrontal cortices (PFC; mPFC and IPFC, respectively) have direct connections with limbic structures that are important in the expression of fear and anxiety. The present study investigated the behavioral effects of excitotoxic lesions of either the mPFC or the IPFC on conditioned and unconditioned fear paradigms. In both unconditioned fear paradigms (open field, elevated plus-maze), lesions of the mPFC decreased anxiety. In fear conditioning, IPFC lesions substantially increased freezing throughout the different phases of the experiment, whereas mPFC lesions increased freezing to contextual cues and showed reduced freezing to discrete cues. These results support the functional role of the PFC in mediating or modulating central states of fear and anxiety and suggest a functional dissociation between the IPFC and mPFC in their role in fear and anxiety.