Large-scale coherence of LFP activities and spikes during wake-sleep γ- and β-oscillations. (A) Field–field correlations: maximum (Max) of the cross-correlation (within a time lag ranging from −50 to 50 ms) averaged over all filtered LFPs (in the γ-frequency range for human and in the β-frequency range for monkey) vs. spatial distance. In both human and monkey, fast oscillations displayed locally correlated dynamics in all states, but the correlations decline with distance. During SWS, correlations stayed high across cortical distances of several millimeters. (B) Spike-field correlations: averaged Rayleigh’s Z value vs. distance from LFP sites for all significantly locked RS and FS neurons. During SWS, FS neurons are phase-locked with a field over up to 3 mm in both human and monkey. This phase-locking disappears during wakefulness. In contrast, RS neurons show less spatial coherence during SWS and no significant correlation with distant LFP sites during wakefulness. (C) Cell–cell correlations: matrices of significant spike synchronization for PMd and MI cells during β-oscillations in monkey. For SWS, the type of target cells is indicated for cells 57/69 with colors (red, FS; and blue, RS). Note that most of the cell–cell interactions over the extent of the array are FS. (D) Spatial distribution of significant cell–cell interactions for two FS cells. Spike synchrony with cell 57/69 can be seen with cells that are spatially far apart. This synchronous spiking could even extend to other cells recorded in another cortical area (from PMd to M1). (E) Example of spike cross-correlogram during SWS and Wake states. Note the presence of a significant peak around zero during SWS that disappears during the Wake state (in green, mean ± 3 SDs of 100 surrogates generated by temporal jittering).