The Rules of Entrainment: Are CA1 Gamma Oscillations Externally Imposed or Locally Governed?

Gamma oscillations (∼30–90 Hz) in the local field potential (LFP) are a widespread signature of information processing in neural circuits and have been linked to cognitive functions ranging from sensory perception and attention to memory encoding and the organization of neuronal assemblies (Engel et al., 2001; Buzsáki and Wang, 2012). Special emphasis has been placed on the gamma-band phase-synchronization among different brain areas, which has been proposed as a mechanism to bind together information processed in distant regions into a unified representation (Engel et al., 2001) or to coordinate different networks engaged in a common memory task (Montgomery and Buzsáki, 2007).