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 lPFC, respectively) have direct connections with limbic structures that are important in the expression of fear and anxiety. The present study investi gated the behavioral effects of excitotoxic lesions of either the mPFC or t he lPFC on conditioned and unconditioned fear paradigms. In both unconditio ned fear paradigms (open field, elevated plus-maze), lesions of the mPFC de creased anxiety. In fear conditioning, lPFC lesions substantially increased freezing throughout the different phases of the experiment, whereas mPFC l esions increased freezing to contextual cues and showed reduced freezing to discrete cues. These results support the functional role of the PFC in med iating or modulating central stares of fear and anxiety and suggest a funct ional dissociation between the lPFC and mPFC in their role in fear and anxi ety.