Potentiation of conditioned freezing following dorsomedial prefrontal cortex lesions does not interfere with fear reduction in mice

In Experiment 1, an auditory conditioned stimulus (CS) was paired with foot shock, except when it was preceded by another stimulus (a visual conditione d inhibitor [CI]). After conditioning, all mice displayed less CS-evoked fr eezing when the CI-CS compound was presented than when the CS was presented alone. However, lesions of the dorsomedial prefrontal cortex (dmPFC) poten tiated CS-evoked freezing on each of the 2 sessions (i.e.. CI-CS and CS alo ne). In Experiment 2, mice were submitted to fear extinction (CS-alone pres entation for 3 days). Lesioned mice exhibited a higher level of freezing be havior than controls on each of the 3 sessions. However, lesioned mice and controls displayed the same rate of reduction of freezing over the 3 days o f extinction. These data in mice support previous studies in rats, which su ggests that the dmPFC is not critical for either conditioned inhibition or extinction of acquired freezing behavior.