i2eye with neuroscientist Karim Nader

i2eye with neuroscientist Karim Nader

Memories can be altered with liberating results
July 24, 2007
© Owen Egan

We all have embarrassing or painful memories we wish we could erase, but what if we could really do it? Karim Nader, a researcher at McGill University, has made it possible, or at least made it so that you’re no longer traumatized by them. In 2000, he turned the study of memory on its head when he proved that memories are not perfect, and that it is possible to dull excessively painful memories. By altering traumatic memories, people can overcome them. His research inspired the Jim Carrey and Kate Winslet movie, Eternal Sunshine of the Spotless Mind, where the two characters have their volatile relationship erased from their memories. Earlier this year, Forbes magazine included him as one of 10 revolutionaries who could completely change the world. InnovationCanada.ca asked Nader to share his insights into memory making and breaking.

InnovationCanada.ca (IC): How do memories work? What makes them changeable?

Karim Nader (KN): The whole idea is that when you acquire a new memory, it’s not stored in the brain instantaneously, but takes a few hours before the changes in neuron connections become stable. The old thinking was that once a memory was stored, it stays fixed in your brain. What I showed was that when you remember a memory, it can become “un-stored” and then must be re-stored in the brain.

So imagine someone goes into a therapist’s office with post-traumatic stress disorder (PTSD). The therapist asks them to describe the trauma. They remember it, and the memory goes back to its unstable state. If, during the process of re-storage, we can block it from being re-stored, then theoretically we can cure the PTSD. But, even if you could get rid of these memories, you wouldn’t want to completely erase them because a lot of people have had PTSD for 20 or 30 years. If they wake up one day and don’t remember anything, that’s not good.

IC: So if erasing memories isn’t the answer to dealing with trauma, what is?

KN: Memories aren’t stored in a single place in the brain. The brain stores information in different parts, so one part is concerned with conscious things, while other memory systems will remember other things, such as emotional aspects of an experience. Remembering causes the content as well as the emotional parts of memories to undergo this re-storage process. If we can selectively prevent the emotional system from re-storage, then we can turn down the emotional strength of these injuries, but leave the conscious aspect of the memory alone. As it turns out, there’s a drug that can do that.

IC: Why is this research so important?

KN: There are a lot of implications. All psychopathological disorders, such as PTSD, epilepsy, obsessive compulsive disorders, or addiction—all these things have to do with your brain getting rewired in a way that is malfunctioning. Theoretically, we may be able to treat a lot of these psychopathologies. If you could block the re-storage of the circuit that causes the obsessive compulsion, then you might be able to reset a person to a level where they aren’t so obsessive. Or perhaps you can reset the circuit that has undergone epilepsy repeatedly so that you can increase the threshold for seizures. And there is some killer data showing that it’s possible to block the reconsolidation of drug cravings.

The other reason why I think it is so striking is that it is so contrary to what has been the accepted view of memory for so long in the mainstream. My research caused everybody in the field to stop, turn around and go, “Whoa, where’d that come from?” Nobody’s really working on this issue, and the only reason I came up with this is because I wasn’t trained in memory. [Nader was originally researching fear.] It really caused a fundamental reconceptualization of a very basic and dogmatic field in neuroscience, which is very exciting. It is the first time in 100 years that people are starting to come up with new models of memory at the physiological level.

IC: Have you performed a successful memory treatment on a human?

KN: One woman suffering from PTSD had been raped by a doctor when she was 14. The woman didn’t tell anyone about it for decades. She came in for our treatment, and afterwards, she talked with the people at the 60 Minutes TV show. They couldn’t believe how much detail she went into. Here was a woman who was apparently getting undressed in the dark in front of her husband because she was so overwhelmed from the trauma. Then, after our treatment, she’s suddenly telling her story in front of zillions of people and finally able to get undressed with the light on with her husband.

That’s an example where if you really understand brain mechanisms and how these things work, you can be very surgical in your therapeutic approach. All her memories were still there; we didn’t compromise any of the details. All we did was stop the memory from being overwhelming. That’s what we’re trying to do; stop memories from being incapacitating, and turn them into normal bad memories so people can cope with them and go on with their lives.

IC: What did you think about the movie Eternal Sunshine of the Spotless Mind?

KN: This is one time where I think science and life are better than art because that movie certainly shows one extreme that obviously has bad consequences. What we are trying to do is be more selective in the kinds of memories we are trying to block and restore.

IC: You were named one of Forbes’ “10 People Who Could Change The World.” How has that changed you personally or professionally?

KN: Well, I took the day off. I looked down at my Blackberry and was like, “Wow, what a cool email!” It was great. It’s not the kind of thing you ever think about, and it was just totally humbling. I still can’t get my mind around it. So you just dive back into the work and keep going.

It hasn’t affected me too much professionally. I was hoping that all these people would want to fund my work privately, and I could spend all my time doing experiments and not writing grants, but that hasn’t happened yet. [Laughs]

For more information, read the article “The Trauma Tamer” in McGill University’s magazine (fall 2006) Headway.