Plasticity in oscillatory coupling between hippocampus and cortex.

Neural oscillations observed in local field potentials (LFP) represent gross cellular activity near the recording electrode. Coupling of oscillations in distributed brain circuits has been proposed to enhance communication across the circuits, and the plasticity in oscillatory coupling can underlie flexible task learning, but the direct evidence has been lacking. Recently, evidence for plasticity in oscillatory coupling in theta, beta and gamma bands has been obtained in memory circuits consisted of the hippocampus and its connected areas, suggesting importance of oscillatory coupling plasticity in memory processing. I hypothesize that such plasticity in oscillatory coupling could be a key mechanism for enhancing inter-regional neural communication, especially in the entorhinal-hippocampal and prefrontal-hippocampal memory circuits that underlie formation, control and retrieval of memory.