Enzyme PKMzeta can aid in reviving old memories and keeping them fresh in your mind: "Boosting levels of PKMzeta helped rats recall, in great detail, events they had experienced many days beforehand. Lowering levels of the enzyme caused the rats to forget old memories more quickly. What's remarkable about this discovery is that the enzyme can help the animals recall these old memories even if they weren't boosting their levels of PKMzeta at the time the memories were formed. If the same treatment works for humans, we could be looking at a way to deal with age-related memory loss. And a way to help us recall information we once knew intimately, but which has grown cloudy as the years have passed."