Figure 2.

Cortical and hippocampal ripples are generated during NREM and waking. A, Orbitofrontal ripples from one channel during NREM. Ai, Average broadband LFP. Aii, Average time-frequency plot. Aiii, Example broadband unfiltered 3 s sweep (black) with 70-100 Hz bandpass analytic amplitude (blue) and below the same example, 400 ms sweep (black) with 70-100 Hz bandpass (blue). B, Same as in A, but during waking. C, Same as in A, but with hippocampal ripples (note ripple on sharp-wave peak). D, Same as in C, but during waking. E–H, Same as in A, but from other cortical regions. I–L, Grand average time-frequency plots across all channels in neocortex (N = 273) during NREM (I) and waking (J), as well as in hippocampus (N = 28) during NREM (K) and waking (L). Note the highly consistent and focal concentration of power centered at ∼90 Hz, the occurrence of cortical ripples on the down-to-upstate transition during NREM, and that some channels show increased power in the 10-16 Hz spindle band coinciding with the ripples. All plots represent ripples detected on bipolar SEEG channels. ERSP, Event-related spectral power.