美国国家公共电台 NPR Steve Ramirez: If We Could Erase Memories ... Should We?

GUY RAZ, HOST:

So we've just been hearing from Elizabeth about how easy it is to manipulate memories through the power of suggestion. But what if we could take it one step further?

(SOUNDBITE OF MUSIC)

RAZ: So, Steve, first of all, introduce yourself. Tell me your first and last name, and what do you do?

STEVE RAMIREZ: Sure. My name's Steve Ramirez, and I'm an assistant professor of neuroscience at Boston University.

RAZ: And Steve's research is focused on a different kind of memory manipulation, and his interest in this, it all began with a breakup.

RAMIREZ: Yeah. So it turns out breakups are not fun.

RAZ: It was during his first year of grad school.

RAMIREZ: And I was going through a pretty, like, I would say traumatic in quotes breakup.

RAZ: And during that breakup, Steve started to relate to a character he'd seen in a movie, "Eternal Sunshine Of The Spotless Mind" with Jim Carrey.

RAMIREZ: And Kate Winslet.

RAZ: Kate Winslet, of course, yeah. And what's that story again?

RAMIREZ: Yeah. So the premise 3 is that, you know, this is sometime in the near future where you can go in and erase 4 memories.

(SOUNDBITE OF FILM, "ETERNAL SUNSHINE OF THE SPOTLESS MIND")

JIM CARREY: (As Joel Barish) She's there with this guy. And she looks at me like she doesn't even know who I am.

RAMIREZ: And then this couple that recently broke up was so debilitated 5 by their once-fond memories of each other that Jim Carrey's character wants to go in and have a small procedure where they erase those memories.

(SOUNDBITE OF FILM, "ETERNAL SUNSHINE OF THE SPOTLESS MIND")

UNIDENTIFIED ACTOR #1: (As character) Actually creating a map of your brain.

UNIDENTIFIED ACTOR #2: (As character) OK. Let's get started.

RAMIREZ: And then, as those memories are being erased 6, he starts realizing like maybe - maybe I don't want to erase them, or maybe if I do erase them, it's going to change my identity.

(SOUNDBITE OF FILM, "ETERNAL SUNSHINE OF THE SPOTLESS MIND")

CARREY: (As Joel Barish) Please, let me keep this memory, just this one.

RAMIREZ: Are you doomed 7 to repeat the past if you can't remember it? So the premise of the movie is, would you do it?

RAZ: You are a neuroscientist. You study the brain.

RAMIREZ: Yes.

RAZ: Is that - is that movie, like, plausible 8 in any way?

RAMIREZ: So yes and no. The idea that you can erase a memory, like, yeah. I mean, like, we - you can see cases of amnesia 9 that happens during a particular kind of brain damage or Alzheimer's or things like that. So we know that memories can be erased. It's just a matter of how. Like, what's - what's the intervention 10 in the brain that's leading to memory erasure 11?

And in the movie, it kind of throws the baby out with the bathwater a little bit too much because you don't have to get rid of the entire memory of this person and the breakup and the sights and sounds and smells. So given what we know about neuroscience these days, we can go in and try to suppress, for example, the emotional components 12 of a memory but leaving the memory of what happened intact.

RAZ: So that difficult breakup Steve had in college, it eventually led him to design a research experiment a lot like the one in the movie. He tells a story on the TED 2 stage. And just a quick note - Steve was joined onstage by his former collaborator 13 Xu Liu, who sadly passed away in 2015.

(SOUNDBITE OF TED TALK)

RAMIREZ: For the longest time, all I would do is recall the memory of this person over and over again, wishing that I could get rid of that gut-wrenching, visceral, blah feeling. Now, as it turns out, I'm a neuroscientist, so I knew that the memory of that person and the awful emotional undertones that color in that memory are largely mediated 14 by separate brain systems. And so I thought, what if we could go to the brain and edit out that nauseating 15 feeling but while keeping the memory of that person intact?

And then I realized maybe that's a little bit lofty for now, so what if we could start off by going into the brain and just finding a single memory to begin with? Could we jumpstart that memory back to life, maybe even play with the contents of that memory? All that said, there is one person in the entire world right now that I really hope is not watching this talk.

(LAUGHTER)

XU LIU: As neuroscientists, we're working the lab with mice trying to understand how memory works. And today, we hope to convince you that now we're actually able to activate 16 a memory in the brain at the speed of light. To do this, there's only two simple steps to follow. First, you find and label a memory in the brain, and then, you activate it with a switch - as simple as that.

(LAUGHTER)

RAZ: Well, their experiment was a little more complicated than that. Basically, Steve and Xu brought a bunch of mice to their lab and then looked at the memory region of their brains called the hippocampus, and then they shot pulses of light into certain cells that were associated with a specific memory. The idea was to implant 17 a new memory in place of the old one. It's a technique called optogenetics.

RAMIREZ: Opto meaning light and then genetics, of course, because genetics. Like, that's how we go in and start engineering these brain cells. And it's literally 18 shooting a laser into the brain. It's a small optic fiber 19 that's about the width of a cocktail 20 straw, and you can gently nestle it in whatever brain area you would like and then shoot light onto that brain area and then see what happens when you turn those brain cells on. And we did that successfully with a memory.

RAZ: Oh, wait, wait, hold on one second. What was the memory you were trying to reactivate? Like - I don't know - like, the mouse was, like, eating a big piece of cheese or something like that.

RAMIREZ: (Laughter) So mice can form a million and one different kinds of memories. But we wanted to start with one where we could say, OK, the animal looks like it's recalling the memory or not. Like, we wanted it to be as binary 21 as it gets. And to do that, we chose to try to activate a mildly negative memory and not because we are evil scientists in white coats and you want to give these mice a negative experience. No, it's that recalling a negative memory in animals is easier to look at and say, well, if the animal is recalling a negative memory, usually what they do is they just huddle 22 in a corner and remain immobile. We call it freezing behavior because the animal looks like it's freezing in place.

So we were trying to reactivate a freezing response. Like, did the animal freeze when we turned the light on? Because, if so, it begins to support the idea that the animal's recalling a negative memory, which we had successfully demonstrated.

RAZ: Right. So - OK, so the mouse freaks out or gets really scared because all of a sudden you've probably triggered a memory of it being, you know, cornered by a cat or something. I watched a lot of "Tom And Jerry." But who knows what it was. It was some bad experience. And then what happened when you removed the shining light from the brain?

RAMIREZ: Then the behavior goes back to normal. It doesn't show evidence of recalling a memory anymore. Now, that's good and bad. So that's good because it means, you know, we can say that those effects are, quote, unquote, "reversible" because you can induce memory and then you can reverse it and go back to some kind of baseline. It's not good if you're trying to reprogram the brain permanently 23 and especially in a therapeutic 24 manner, which is some of the stuff that my lab currently does now, which is what if you turned those brain cells on and off a lot? What if you chronically 25 stimulate 26 those brain cells to try to induce some kind of therapeutic-like changes in the brain?

RAZ: Yeah. I mean, you could imagine. And we're not there yet. We're very far away from this. But you could imagine taking somebody who experienced a trauma 1 or a veteran from war who was suffering from PTSD and activating 27 neutral memory in their brain so as to prevent them from re-experiencing that trauma.

RAMIREZ: So exactly. And it's not at all crazy because it's something that - you know, we're not going to go in and start doing optogenetics in human brains to try to manipulate memories anytime soon. But what we try to do is say - well, OK, so mouse brains are like in 1988 - I don't know - Toyota Camry. And then human brains are probably like a 2030 Lamborghini.

So they work slightly differently, but the principles of how wheels move, the principles of how an engine starts are still there. They're still conserved 28. So we can still learn a lot about human brains by having an ongoing 29 dialogue between rodent 30 researchers and human brain researchers.

(SOUNDBITE OF TED TALK)

RAMIREZ: And for me personally, I see a world where we can reactivate any kind of memory that we'd like. I also see a world where we can erase unwanted memories. Now, I even see a world where editing memories is something of a reality because we're living in a time where it's possible to pluck questions from the tree of science fiction and to ground them in experimental reality.

And finally, what do we make of all this? How do we push this technology forward? These are the questions that should not remain just inside of the lab. So let's think together as a team about what this all means and where we can and should go from here.

(SOUNDBITE OF MUSIC)

RAZ: I mean, you have to think that this technology could fall into the wrong hands. I mean, somebody could want to implant false memories in a person or eliminate important memories that could bear witness. I mean, that's the path we're heading down.

RAMIREZ: You know, the way I think about it is everything under the sun could be used for good and bad. And now - you know, Mark Twain has this great quote that history doesn't repeat itself but it does rhyme. So we could take lessons from the history of science and ask - the last time technological 31 game-changers happened, what did people do good? And what did people do bad? And, like, when it went bad, why did it go bad?

So for instance, one thing that we can take a lesson from is from the Human Genome Project, which, in the '80s, was a humongous buzz. And then it was this race to sequence the human genome. And then immediately, of course, people were thinking like - well, what if we can modify our own genomes? Like, this smells a lot like eugenics. Like, how do we prevent that from happening?

And what happens is that conversation starts two decades before the human genome was even sequenced. And by starting that conversation 20 years ago, you have the social and ideally legal infrastructure 32 to prevent its misuse 33. So we can do the same thing with manipulating memories now - that by worrying about it being misused 34, we can have this conversation now - two, three decades in advance of whenever something like this is possible in people - and when Day 0 gets there, we'll have enough social and legal infrastructure where it's on everybody's minds and ideally keep it in a regulated and morally responsible manner.

RAZ: But I mean, even if we have all the right conversations. I mean, even if we don't misuse this technology, I'm still a little bit troubled by the potential of this because it suggests that nothing is going to be real. Like, everything could potentially be falsified or manipulated or invented.

RAMIREZ: And I think that, in that case, you know we basically - we reinvent ourselves daily with the new memories that we form. And I think it's more of - ideally, we could embrace the dynamism that is memory.

Or, like, we can embrace that - by being in a reconstructive process, for instance, some people think that - or have shown, for instance, that the same machinery 35 that helps us recall memories, such as the hippocampus, by and large is not just the same machinery that's responsible for false memories, but it's also the same machinery that lets us imagine the future and lets us put ourselves in future scenarios 36.

And then, in that case, having a reconstructive, you know, chalkboard there is a good thing because we can put ourselves, in our mind's eye, in future situations. And we can imagine what tomorrow is going to be like. And we can imagine what we're going to do and recombine elements of our past into something new, into something creative.

So there is something to say about - like, the fact that memory is modifiable might also permit for us to be flexible in the way that we imagine the future, which, you know, sort of is one of the core things that define us as humans.

(SOUNDBITE OF MUSIC)

RAZ: Steve Ramirez - he's an assistant professor of neuroscience at Boston University. You can watch the full talk he gave with Xu Liu at ted.com.

(SOUNDBITE OF SONG, "HIDDEN PERSUASION 37")

FRANK SINATRA: (Singing) For real - your hidden persuasion seems quite sincere. Perhaps my evasion 38 is meaningless fear.

RAZ: Hey, thanks for listening to our show, Manipulation, this week. If you want to find out more about who was on it, go to ted.npr.org. To see hundreds more TED Talks, check out ted.com or the TED app. And you can listen to this show anytime by subscribing 39 to our podcast. Do it now on Apple Podcasts or however you get your podcasts.

Our production staff here at NPR includes Jeff Rogers, Sanaz Meshkinpour, Jinae West, Neva Grant, Rund Abdelfatah and Rachel Faulkner with help from Daniel Shukin and Tony Lu. Our intern 40 is Benjamin Klempay. Our partners at TED are Chris Anderson, Colin Helms, Anna Phelan and Janet Lee.

I'm Guy Raz, and you've been listening to ideas worth spreading right here on the TED Radio Hour from NPR.

(SOUNDBITE OF FRANK SINATRA'S "HIDDEN PERSUASION")