Fear states involve amygdala interactions with an extended network and in particular, its dense reciprocal connectivity with the mPFC. In this study, we investigated oscillatory network dynamics during fear discrimination. Fear-conditioned tones elicited increased theta-fast gamma coupling within the BLA, while the power of these fast gamma oscillations was paradoxically decreased. During the explicitly unpaired CS−, which signaled relative safety, fast gamma power was increased compared to the CS+, despite weaker coupling to local BLA theta. This elevated gamma power was associated with a predominant mPFC-to-BLA directionality and increased entrainment of BLA gamma by mPFC theta. A similar increase in BLA gamma power and switch towards an mPFC-to-BLA directionality was also seen after extinction of learned fear, and in the safe areas within the open field, a test of innate anxiety. Thus the data support a common mechanism for the suppression of both learned and innate fear responses, involving directional information flow from the mPFC to the BLA and mPFC entrainment of fast gamma-resonant circuits in the BLA.
