The hero in Memento had a certain condition that prevented him from making new memories. He couldn't remember the start of a conversation by the end of the conversation. He couldn't remember who a person was, if that person had introduced themselves to him a few minutes before. When he learned a new fact, or phone number, he had to repeat it obsessively until he could write it down.
If that sounds familiar, it's because we all have this experience with our memories. When we're going somewhere, or when we've just learned a phone number and are typing it into our phones, we keep it in mind, and then forget it when we're done - or if we're unlucky just before we're done.
But what's the difference between us, who may have a hazy recollection of how we got on to this particular conversational topic, and the character, who had no idea? Parvalbumin. Parvalbumin is expressed by certain neurons in the brain. Recently, scientists took out those neurons in lab rats. The study was meant to examine the effects of PCP use. The scientists set the mice in the mice in the maze and found that, though they made their way through, they repeatedly revisited certain branches of the maze, which their undamaged brethren only visited once. Scientists believe that they did so because they could not remember where they had just been.
Other than a forgetful nature, these Memento mice continued to lead normal lives, having no increase in anxiety or motor function. Over time, and with repeated practice, the mice learned to navigate the maze that had baffled them, just like their counterparts in the control group. Even when they couldn't remember what they were learning - they kept learning all the same.
Via Ars Technica.