Figure 2.

A, Hippocampal activity during different behavioral states, shown for example 3 s windows during rest epochs (pink outline; left column) and search epochs (orange outline; right column). Recordings from m1 shown in top two rows and from m2 on bottom two rows. Time–frequency-resolved spectra were generated from 600 ms segments, shifted in 6 ms increments, windowed with a Hamming window, 1/f normalized, and z-transformed. White trace, superimposed on the spectra, is the broadband LFP of the same 3 s window taken from a z-score transform of the entire session. The scale shown in SDs applies to all plots for a given animal. Below search epochs, the concurrent on-screen eye position (horizontal and vertical) are represented as degrees of visual angle (VA; the monitor encompasses 38.5 × 30.9° VA). B, Difference in grand average FFT power across behavioral epochs. For each animal, the average FFTs of epochs for search versus rest were calculated (m1: 66 rest epochs, 1258 search epochs; m2: 100 rest epochs, 2584 search epochs). The average FFT for each epoch type was calculated, min–max normalized to a range of 0–1, and resultant rest values subtracted from the search values. First two peaks (rest > search) are highlighted with pink markers; the trough where search-epoch frequencies become prominent are highlighted with an orange marker.