processes of synaptic downscaling during sleep (shown as the hippocampal trace vanishing)
lead to the preparation of the brain to encode new information during the next wake phase (again depicted by thick and dashed lines in hippocampus and cortex, respectively).
While the synaptic downscaling hypothesis has been most rigorously applied to cortical learning tasks, recent research has provided evidence for downscaling in the hippocampus during REM sleep. Processes of local synaptic strengthening may work in concert with global downscaling processes to provide reliable and efficient memory traces. Bottom panel is adapted from.
downscaling