Coherent theta oscillations and reorganization of spike timing in the hippocampal- prefrontal network upon learning

Neuron. 2010 Jun 24;66(6):921-36. doi: 10.1016/j.neuron.2010.05.013.


To study the interplay between hippocampus and medial prefrontal cortex (Pfc) and its importance for learning and memory consolidation, we measured the coherence in theta oscillations between these two structures in rats learning new rules on a Y maze. Coherence peaked at the choice point, most strongly after task rule acquisition. Simultaneously, Pfc pyramidal neurons reorganized their phase, concentrating at hippocampal theta trough, and synchronous cell assemblies emerged. This synchronous state may result from increased inhibition exerted by interneurons on pyramidal cells, as measured by cross-correlation, and could be modulated by dopamine: we found similar hippocampal-Pfc theta coherence increases and neuronal phase shifts following local administration of dopamine in Pfc of anesthetized rats. Pfc cell assemblies emerging during high coherence were preferentially replayed during subsequent sleep, concurrent with hippocampal sharp waves. Thus, hippocampal/prefrontal coherence could lead to synchronization of reward predicting activity in prefrontal networks, tagging it for subsequent memory consolidation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / drug effects
  • Action Potentials / physiology*
  • Animals
  • Behavior, Animal
  • Dopamine / pharmacology
  • Hippocampus / physiology*
  • Male
  • Maze Learning / physiology*
  • Neural Inhibition / drug effects
  • Neural Inhibition / physiology
  • Neural Pathways / physiology
  • Neurons / classification
  • Neurons / drug effects
  • Neurons / physiology*
  • Periodicity*
  • Prefrontal Cortex / physiology*
  • Principal Component Analysis
  • Rats
  • Rats, Long-Evans
  • Reward
  • Spectrum Analysis / methods
  • Time Factors


  • Dopamine