Why You Must Not Trust Your Memories – Or Anyone Else’s

By Shlomo Maital   


    The writer Vladimir Nabokov once said,  “ the more you love a memory the stronger and stranger it becomes.”       Emphasize STRANGER.   Because scientists at MIT have shown, each time we retrieve a cherished memory and relive it,  we alter it.  And if you do this 100 times, the memory itself can bear no relation with what actually happened.   Humans are not elephants, which, as we know, never ever forget anything. 

   Writing in the July 25 edition of The New York Times, * James Gorman reports this:

     “….scientists at the Riken-M.I.T. Center for Neural Circuit Genetics at the Massachusetts Institute of Technology say they have created a false memory in a mouse, providing detailed clues to how such memories may form in human brains.   Steve Ramirez, Xu Liu and other scientists, led by Susumu Tonegawa, reported Thursday in the journal Science that they caused mice to remember being shocked in one location, when in reality the electric shock was delivered in a completely different location.    The finding, said Dr. Tonegawa, a Nobel laureate for his work in immunology, and founder of the Picower Institute for Learning and Memory, of which the center is a part, is yet another cautionary reminder of how unreliable memory can be in mice and humans. It adds to evidence he and others first presented last year in the journal Nature that the physical trace of a specific memory can be identified in a group of brain cells as it forms, and activated later by stimulating those same cells.

   How was this scientific magic done?   Dr. Tonegawa’s team first put mice in one environment and let them get used to it and remember it. They identified and chemically labeled the cells in the animals’ brains where that memory was being formed. The mice were not shocked in that environment.   A day later, in a completely different environment, the researchers delivered an electric shock to the mice at the same time that they stimulated the previously identified brain cells to trigger the earlier memory.   On the third day, the mice were reintroduced to the first environment. They froze in fear, a typical and well studied mouse behavior, indicating they remembered being shocked in the first environment, something that never happened. The researchers ran numerous variations of the experiment to confirm that they were in fact seeing the mice acting on a false memory.   The tools of optogenetics, which are transforming neuroscience, were used to locate and chemically label neurons, as well as make them susceptible to activation by blue light transmitted by a fiber optic cable. With these techniques the researchers were able to identify and label which neurons were involved in forming the initial memory of the first environment, and to reactivate the labeled cells a day later with light.

    Dr. Tonegawa said that part of the importance of the research is “to make people realize even more than before how unreliable human memory is,” particularly in criminal cases when so much is at stake.    That unreliability, he said, prompts a question about evolution: “Why is our brain made in such a way that we form false memories?”

    His answer:   “No one knows, he said, but he wonders if it has to do with the creativity that allows humans to envision possible events and combinations of real and imagined events in great detail. That rich internal experience fuels work in the arts and sciences and other creative activities, he said. “Unless you have that kind of ability, there is no civilization,” he said.

   In a previous blog, I reported on Dan Ariely’s research, showing that creative people are less honest.  Dr. Tonegawa’s theory fits well with this.  Creative people simply invent things – in the past, as well as in the future.  

        Precisely because we can re-imagine the past,  we can also imagine the future. 

        Personally, I find it very helpful to re-imagine the past.  If you are troubled by a memory,  simply reinvent it.  Soldiers suffering from post traumatic stress disorder (PTSD), and there are many thousands of them, relive the traumatic event precisely as it happened, again and again and again.  Perhaps we can help them reinvent it…. Or simply get the neurons that fire up the memory to turn off.    

      Also, many thousands of innocent persons have been sent to jail by testimony of witnesses which proved wrong.  We now understand why.   They are not liars. They simply remember events differently than they actually happened.  The legal system will now have to take this into account. 

* New York Times, July 25, 2013  “Scientists Trace Memories of Things That Never Happened”.  By JAMES GORMAN