The Frontal Cortex

Recovering Lost Memory

Posted by Jonah Lehrer on January 31, 2008
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Baudelaire famously described his memory as “a tomb, a corpse filled Potter’s field/a pyramid where the dead lie down by scores/I am a graveyard that the moon abhors.” Well, the neural reality of the brain suggests that his poetic metaphors weren’t such exaggerations. That, at least, is the implication of a bizarre new finding:

Surgeons made this accidental discovery while a 50-year-old-male patient was undergoing “deep brain stimulation,” as part of an experimental treatment for obesity.

With the patient under local anesthesia, but fully awake, surgeons traveled into the deepest recesses of the brain, moving gingerly at a quarter of an inch an hour, listening to electrical “pulses,” as millions of brain cells communicated with each other.

But amazingly, in the midst of the operation, something completely unexpected happened. The patient suddenly reported a flood of intricately detailed memories from an incident decades ago.

Think about how surreal this is: the man thought he had forgotten these memories. He thought they had faded from his brain. And yet, the memories were still there, persisting as an immutable network of interconnected neurons. The question, of course, is how this persistence occurs. After all, the cells of the brain, like all of our cells, are in constant flux. The average half-life of a brain protein is only 14 days. Our hippocampal neurons die, and are reborn, the mind in a constant state of reincarnation. In my book, I talk about the prion-CPEB hypothesis, which could possibly account for experiments like this and the sentimental fiction of Proust. (Like the subject of this neurological report, Proust was convinced that he’d forgotten all about Combray and his childhood. But then he ate the madeleine: the cookie was like a jolt of electricity.)

Thanks to Sarah for the tip!

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  1. #1 Scott Belyea
    January 31, 2008

    …the man thought he had forgotten these memories. He thought they had faded from his brain. And yet, the memories were still there, persisting as an immutable network of interconnected neurons. The question, of course, is how this persistence occurs.

    I suggest that there’s an equally interesting second question – are the memories accurate, and if not, why not?

    I’ve recently had the experience of going back to two places I hadn’t been in about 15 years. One was a wilderness lake, the other a house. I had quite specific and detailed memories of each … and much of what I “remembered” was wrong.

    This was a different thing, of course; these memories were not recovered, but have always been there. But that raises another question – are you aware of any work done on whether there’s any difference in accuracy between “regular” memories and “recovered” memories?

  2. #2 6EQUJ5
    January 31, 2008

    What the surgeons produced in him were images. To call them memories presumes the imagery got verified. Fever dreams can give very intense and realistic experiences but they are only dreams.

  3. #3 _Arthur
    January 31, 2008

    Here is Baudelaire poem “spleen”, with translation:
    http://www.everything2.com/index.pl?node_id=46821

    That brings back memories !

    “J’ai plus de souvenirs que si j’avais mille ans.
    Un gros meuble à tiroirs encombré de bilans,
    De vers, de billets doux, de procès, de romances,
    Cache moins de secrets que mon triste cerveau. ”

    I have more memories than if I were a thousand years old.
    A large piece of furniture with drawers filled with ledgers,
    Verses, love letters, lawsuits, love songs,
    With heavy knots of hair rolled in receipts,
    Hides less secrets than my sad brain.

  4. #4 qetzal
    January 31, 2008

    This is also interesting:

    Over the next year, researchers discovered that the man, who initially had normal memory before the operation, now scored significantly higher on memory and learning tests when the current was turned on.

    That suggests the stimulated area really is involved in memory, not just hallucination.

    Also, wasn’t there a recent claim that suggested every time you remember something, the ‘original’ memory is in some sense destroyed, and has to be re-remembered again?

    Interesting stuff!

  5. #5 _Arthur
    January 31, 2008

    I can’t find where I readt that, but as I understand it, memory possibly evolved as a may to record emotions (hormones) related to sensorial input, more than the sensorial inputs (images, sounds, odors) themselves. Am I completely off-base ?

  6. #6 Marc
    February 2, 2008

    The other interesting aspect of this story is that deep brain stimulation, a method that most of us had assumed to be outdated (if not primitive) is slowly making a comeback as an effective therapy for a number of disorders. It’s being used to treat Parkinson’s tremors, chronic pain, and may eventually be used more widely with comatose patients after the success last year in using it to wake someone from a minimally conscious state. And we still don’t really know why it’s working…

  7. #7 Rachael
    February 3, 2008

    Qetzal: I am not very familiar with reconsolidation theory, but yes, this is a new trend in memory theory. Rather than saying that a memory was “destroyed” after you remember something, a more accurate description might be that a memory becomes labile upon being accessed. If a rat is trained for a particular memory (Eg associating a tone with a shock), the memory is accessed (by playing the tone minus the shock), and a researcher applies a protein synthesis inhibitor, then the memory is destroyed – but only if the researcher applies the inhibitor (since it inhibits the memory from being stored again). Exposing a rat again and again to a tone (without any shock) will eventually weaken the memory but it takes a long time for that to happen. I think the current idea is that accessing memories brings them forth into a state where they can be modified, and the experiments with protein synthesis inhibitors demonstrate that there is no permanent copy of the memory – all of the memory becomes labile upon being accessed.

    Anyway, it’s interesting. Following the trail of ones own memories is fascinating. Isn’t it often the case that you think you’ve forgotten something only to remember it later?

  8. #8 Jill
    February 3, 2008

    If his memories were indeed verified, I’m reminded of the experiences reported by people under Ibogaine treatment: the bringing back of lost memories in vivid detail. I wonder if there’s a connection.

  9. #9 Joey
    May 11, 2011

    I lost all memories before june 26 2007 from a beating i recieved.Im 44 or 45 and have no history , any suggestions