Theta phase segregation of input-specific gamma patterns in entorhinal-hippocampal networks

Neuron. 2014 Oct 22;84(2):470-85. doi: 10.1016/j.neuron.2014.08.051. Epub 2014 Sep 25.


Precisely how rhythms support neuronal communication remains obscure. We investigated interregional coordination of gamma oscillations using high-density electrophysiological recordings in the rat hippocampus and entorhinal cortex. We found that 30-80 Hz gamma dominated CA1 local field potentials (LFPs) on the descending phase of CA1 theta waves during navigation, with 60-120 Hz gamma at the theta peak. These signals corresponded to CA3 and entorhinal input, respectively. Above 50 Hz, interregional phase-synchronization of principal cell spikes occurred mostly for LFPs in the axonal target domain. CA1 pyramidal cells were phase-locked mainly to fast gamma (>100 Hz) LFP patterns restricted to CA1, which were strongest at the theta trough. While theta phase coordination of spiking across entorhinal-hippocampal regions depended on memory demands, LFP gamma patterns below 100 Hz in the hippocampus were consistently layer specific and largely reflected afferent activity. Gamma synchronization as a mechanism for interregional communication thus rapidly loses efficacy at higher frequencies.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Action Potentials / physiology
  • Animals
  • Entorhinal Cortex / physiology*
  • Gamma Rhythm / physiology*
  • Hippocampus / physiology*
  • Interneurons / physiology*
  • Male
  • Models, Neurological
  • Pyramidal Cells / physiology*
  • Rats, Long-Evans
  • Theta Rhythm / physiology*