Both theta- and gamma-frequency activity was seen in the BLA during the CS+ (Figure 1). We decomposed the signal with wavelets (Supplementary Experimental Procedures) to extract separate frequency components from the ongoing LFP. This analysis revealed two frequencies of gamma oscillations (Figure 1B), which appeared as distinct peaks in the distribution of instantaneous gamma frequency (peaks at 55 and 90 Hz, respectively; Figure S2A). These bands, termed slow (40-70 Hz) and fast gamma (70-120 Hz), could also be separately extracted using bandpass filters (Figure 1B, bottom traces).
