Hippocampo cortical coupling mediates memory consolidation during sleep
Memory consolidation is thought to involve a hippocampo cortical dialog during sleep to stabilize labile memory traces for long term storage. However, direct evidence supporting this hypothesis is lacking. We dynamically manipulated the temporal coordination between the two structures during sleep following training on a spatial memory task specifically designed to trigger encoding, but not memory consolidation. Reinforcing the endogenous coordination between hippocampal sharp wave ripples, cortical delta waves and spindles by timed electrical stimulation resulted in a reorganization of prefrontal cortical networks, along with subsequent increased prefrontal responsivity to the task and high recall performance on the next day, contrary to control rats, which performed at chance levels. Our results provide, to the best of our knowledge, the first direct evidence for a causal role of a hippocampo cortical dialog during sleep in memory consolidation, and indicate that the underlying mechanism involves a fine tuned coordination between sharp wave ripples, delta waves and spindles.
Nature Neuroscience