Most memories have some kind of emotion attached to them. For example, you might be overcome with negative feelings when you think about the time you went on a bad date, or you might feel happy when you think about the time you went camping with your friends.

What if you could replace the memory of the bad date into a good one? That's just what neuroscientists at MIT have been doing with mice, according to a recent study. Roger Redondo, lead author of the research, says they have found a way to switch bad memories with good ones in mice.