Sleep also seems to be the time when the brain’s two memory systems—the hippocampus(海马体) and the neocortex (新皮质)—"talk" with one other. Experiences that become memories are laid down first in the hippocampus, eliminating whatever is underneath. If a memory is to be retained, it must be shipped from the hippocampus to a place where it will endure—the neocortex, the wrinkled outer layer of the brain where higher thinking takes place. Unlike the hippocampus, the neocortex is a at weaving the old with the new. And partly because it keeps incoming information at bay, sleep is the best time for the" undistracted" hippocampus to shuttle memories to the neocortex, and for the neocortex to link them to related memories.
How can a piece of information become enduring memory in the brain