The activity of PV+ interneurons may also relate to the inverse relationship between gamma power and theta-gamma coupling that we observed. Courtin et al. (2014) demonstrated that the suppression of PV+ interneuron activity in the PL is necessary and sufficient for inducing tone-evoked theta synchrony within the mPFC and freezing. While Courtin et al. did not record from the BLA during inhibition of PV+ neurons in the PL, it is possible that inhibiting these PV+ interneurons also increased mPFC-BLA theta synchrony, enhancing fear responses. Conversely, the activation of mPFC PV+ interneurons may drive circuits required for the directional gamma synchrony and increasing gamma power we report during the CS−.
