Given the strong, zero-phase lag synchrony of mPFC-BLA-vHPC fast gamma oscillations, we tested the possibility that safety modulated gamma in the mPFC and vHPC, like gamma in the BLA. Fast gamma power was lower during the CS+ than the CS− in the mPFC of discriminators (Figure 6B), with no change in the slow gamma or higher spectral ranges (p>.05; data not shown). As in the BLA, better behavioral discrimination between the CS+ and CS− correlated with higher mPFC fast gamma power in the CS− (r=.52; p<.01; Figure 6B). Consistent with these being safety-related changes, individual animals showed an inverse correlation between freezing rate on a given trial and fast gamma power in the mPFC, as in the BLA (Figure S7C). Interestingly, no significant safety-related changes in vHPC gamma were found (Figure 6B), despite strong gamma synchrony with the other two brain structures (Figure 6A).
