Oscillations and hippocampal–prefrontal synchrony

The hippocampus, a structure required for many types of memory, connects to the medial prefrontal cortex, an area that helps direct neuronal information streams during intentional behaviors. Increasing evidence suggests that oscillations regulate communication between these two regions. Theta rhythms may facilitate hippocampal inputs to the medial prefrontal cortex during mnemonic tasks and may also integrate series of functionally relevant gamma-mediated cell assemblies in the medial prefrontal cortex. During slow-wave sleep, temporal coordination of hippocampal sharp wave-ripples and medial prefrontal cortex spindles may be an important component of the process by which memories become hippocampus-independent. Studies using rodent models indicate that oscillatory phase-locking is disturbed in schizophrenia, emphasizing the need for more studies of oscillatory synchrony in the hippocampal–prefrontal network.

► Coherent oscillations are observed across the hippocampus and medial prefrontal cortex (mPFC).
► Hippocampal theta oscillations modulate mPFC during goal-directed behaviors and working memory.
► Bursts of mPFC gamma oscillations, phase-locked to hippocampal theta, may also subserve such tasks.
► Hippocampal sharp waves and mPFC spindles may promote transfer of memories from hippocampus to mPFC.
► Oscillatory phase-locking between hippocampus and mPFC may be disrupted during schizophrenia.