Proc. Natl. Acad. Sci. USA 113: 9363-9368, 2016.
Beta and Gamma oscillations are present in different cortical areas and are thought to be inhibition-driven, but it is not known if this also applies to oscillations in humans. Here, we analyze such oscillations in high-density microelectrode array recordings in human and monkey during the wake-sleep cycle. In these recordings, units were classified as excitatory and inhibitory cells. We find that gamma oscillations in human and beta oscillations in monkey are characterized by a strong implication of inhibitory neurons, both in terms of firing rate, and in their phasic firing with the oscillation cycle. Beta and gamma waves systematically propagate across the array, with similar velocities, during both wake and sleep. However, only in slow-wave sleep, beta and gamma oscillations are associated with highly coherent and functional interactions across several millimeters of the neocortex. This interaction is specifically pronounced between inhibitory cells. These results suggest that inhibitory cells are dominantly involved in the genesis of beta and gmma oscillations, as well as in the organization of their large-scale coherence in the awake and sleeping brain. The highest oscillation coherence found during slow-wave sleep suggests that fast oscillations implement a highly-coherent reactivation of wake patterns, which may support memory consolidation during slow-wave sleep.