Working at Scientific American, known for its spiffy technical illustrations, I always look for material that can show what an article is trying to tell. I’ve never found a better example than this video(below) of a rat fed a drug that wipes out its long-term memory, and which bears a real-life resemblance to the scenario depicted in Eternal Sunshine of the Spotless Mind. The opening paragraphs of the article by Jerry Adler, called “Erasing Painful Memories.”  serves as a running narrative to the video. I’ve included them here:

The rat is on a carousel with clear plastic sides, rotating slowly in a small room. As it looks out through the plastic, it sees markings on the walls of the room from which it can determine its position. At a certain location it receives a foot shock—or, in experimenters’ jargon, a negative reinforcement. When that happens, the rat turns sharply around and walks tirelessly in the opposite direction, so it never reaches that same place in the room again. It will do this to the point of exhaustion.

Question: How do you get the rat to stop walking?

Note that just turning off the shock will not suffice, because the rat will not allow itself to enter the danger zone. The rat needs an intervention that helps it forget its fear or that overrides its response with a competing signal of safety. So much for the rat. Now think of someone who has been wounded in combat and suffers from the vague but real cluster of symptoms called post-traumatic stress disorder (PTSD). He, too, associates specific contexts or stimuli—open spaces, crowds, sudden loud noises—with something painful.

He avoids those circumstances when he can. He is in the same bind as the rat on the turntable: unable to discover for himself that certain situations are now safe. How do we get him to stop running? The rat on the carousel and the veteran on a crowded street are both prisoners of the extraordinary power of pain to forge an indelible impression on the brain: be it mammalian, reptile or even invertebrate.

The rat on the carousel and the veteran on a crowded street are both prisoners of memory, of the extraordinary power of pain to forge an indelible impression on the brain: be it mammalian, reptile or even invertebrate. As some researchers labor to solve the mystery of memory loss in dementia, others are attacking the mirror image problem of how to help patients escape the painful memories that dominate their daily life—and not just those with  PTSD. An emerging new paradigm views such diverse conditions as phobias, obsessive- compulsive disorder, and even addiction and intractable pain as disorders of learning and memory or, more pointedly, forgetting.

Some people never forget the time a spider fell into their glass of milk. Others cannot break the association of certain places or situations with getting high. Now researchers are finding that remembering is not just a process of passively storing impressions. It is a continuous, dynamic activity on the cellular level and an ongoing psychological process open to  manipulation with drugs and cognitive therapy. This is wonderful news for combat veterans and victims of assaults and accidents. What it means for future generations of historians and personal-injury lawyers remains to be seen.

For the rat on the carousel, you can imagine different approaches to extinguishing its fear. You could let it walk to exhaustion and learn for itself that the shock has been turned off—a process psychologists call extinction. Or you could try tinkering directly with the rat’s brain—specifically, the hippocampus, where place memories are formed and stored. Six years ago neuroscientist Todd Sacktor of S.U.N.Y. Downstate Medical Center in Brooklyn, building on work with his former colleague Andre Fenton, did just that. He injected a compound called ZIP into the hippocampus of a rat that had been trained onthe carousel and, after two hours, tested it again and found the fear had been erased. Do that in a combat veteran disabled by PTSD, and you are on the way to a Nobel Prize or a billion-dollar drug bonanza.

The article then goes on to explain other approaches that researchers are undertaking to help people forget or dull bad memories. Adler’s introduction serves as a general description of the video. The specific component segments are:

1. Pretraining: The rat, in this video playing at five times normal speed, gets used to life on the carousel. Note the unactivated, pie-shaped area used to deliver a shock.

2. Training Trial 8 (shock on): Now the shock is turned on, and the rat steers well clear of the demarcated red slice.

3. One-day retention: saline-injected rat (shock off): A day later, a rat injected with harmless saline remembers the aversive shock, steering clear of the triangular zone.

4. One-day retention: ZIP-injected rat (shock off): The rat that has ZIP injected into its brain wanders freely the breadth of the carousel without any memory of having been shocked.

5. Pretraining vs. One-day retention: (Zip- Injected): A side-by-side comparison shows that the Zip-injected rat behaves exactly as it did before it received the first shock.
   
   
   
   
   

9 Comments

1. 1. Eric Zhang 10:23 PM 5/10/12

   It is excited that the experiment operated by neuroscientist Todd Sacktor and his former colleague Andre Fenton has showed a positive signal in which the compounde called ZIP injected into the hippocampus might help people forget or dull bad memories just as the what to the rat.However,there is also a problem arising along with the prospective result.Once this drug-like compound is exploited by terrorists,this compound will risk being illegally used as a compound to dominate other's mind.So,it is the responsibility of the government to limit the use of this drug-like compound-ZIP.

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2. 2. editdroid 10:42 AM 5/12/12

   I want to volunteer for human trials please. There are many things I want to forget. Like the times I saw an M. Night Shymalan movies.

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3. 3. GG 11:58 AM 5/12/12

   The research is flawed, because it claims more than it has proof for.
   
   They claim erasing "negative memories", which implies specificity for negative memories. The natural conclusion is that they do not erase positive memories, but there is no proof for this.
   
   There should have been a positive memory in the experiment, and show that this positive memory is not affected by the drug.
   
   What if this drug erased ALL fresh memories?
   
   Additionally, the experiments focus on freshly made memory. But long-term memory should be tested instead.
   
   Finally, rats do not have the cognitive capacity of humans. Extrapolating rat memory experiments to a person suffering from PTSD is ridiculous.
   

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4. 4. Algie 02:02 PM 5/12/12

   Seems like it would have implications for capital punishment. If the criminal did not remember commiting the crime there would be no reason to execute them.

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5. 5. jtdwyer in reply to GG 07:04 PM 5/12/12

   Good points! The video at least is an example of a "rat fed a drug that wipes out its long-term memory". I doubt its effects are limited to only 'fresh' memories, since even old memories are subject to repeated revision. As I understand, there is a biological distinction between short-term and long-term memories, but even long-term memories are not involatile.
   
   Are PTSD sufferers only haunted by painful memories, or have their ability to accurately and reliably store new memories also been affected? I don't think this has been clinically determined. I suspect that trauma also affects the process involved in storing new memories, so that even if completely eliminating all painful memories were possible, it would not prevent the painful interpretation of new experiences.

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6. 6. Bops in reply to Algie 10:09 PM 5/12/12

   No way, that would be an even better reason to execute a criminal.
   Not remembering doesn't mean not guilty, you do the crime, you are still responsible. Whatever, it's not an excuse for criminal behavior. It's way more dangerous.

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7. 7. sunspot 07:24 PM 5/14/12

   This article is incomplete. You can't call this science, when you give no indication of the effects of ZIP other then to make the grossly inaccurate assumption that because the rat doesn't avoid the shock zone that it forgot about the shock. The story doesn't answer many questions of the scientific reader. For example, if a dentist gives a patient gaseous anesthetic (nitrous oxide), does the patient forget the pain? Does the ZIP turn the rat brain to mush, so the rat is totally confused? Does the ZIP make the rat masochistic, so that it likes the pain and is running around hoping to get zapped?
   
   With so much speculation, and so little fact, I think we should forget this article. Pass the ZIP.
   

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8. 8. Benii in reply to editdroid 08:24 AM 11/16/12

   aaaaa

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9. 9. Benii 08:26 AM 11/16/12

   Hello, i really want to forget som bad memories wich keeps me in anxiety all the time, please please help me to find this, help me and manke me to forget those things i really cannot calm my self please hel me find this drugs, please answere me.

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