Back when I covered the Society for Neuroscience meeting in Chicago, one of the coolest talks I heard was from Elizabeth Phelps, a scientist at NYU who studies fear conditioning. At the meeting, Phelps presented unpublished data on a method of eliminating fear memories that sounded like science fiction – specifically, Eternal Sunshine of the Spotless Mind. Today, that research was published in the journal Nature, which has also posted a very cool video demonstration of the procedure (with some nice, scary ambient background music to up the sci-fi factor).
The method capitalizes on a peculiar aspect of memory called reconsolidation. Basically, if you think of memory as a library, every time you recall a particular event, person, or association, it’s like checking out a book. While that book is in your possession, you can change it – scrawling a note in the margins, or ripping out a page – before checking it back in to the library. That process is called reconsolidation, the idea that memories are vulnerable to being changed when they are recalled.
Other groups have shown in rats and humans that treatment with a particular drug during reconsolidation can help eliminate a memory. One study published last year used a drug called propranolol, normally used to treat hypertension, to try and block emotionally painful memories in patients with post-traumatic stress disorder – patients were asked to recall the “traumatic event,” then given the drug, and researchers found a decrease in stress response when asked to again recall the event a week later. But treating people with drugs to zap away painful emotions associated with memories could carry unwanted side effects, both of the drug itself and of the potential for losing desirable memories alongside those one wishes to eliminate. So Phelps’ drug-free method promises a “non-invasive” and specific means of stripping the fear away from phobias.
The video does a better job of explaining the experiments, but think of it like this: if you are scared of spiders, every time you see a spider you check out a book from your memory library called – to draw from a personal fear – “Spiders Are Scary.” If you check out that book and are repeatedly exposed to spiders that don’t do anything harmful to do you (a process called extinction), you’ll gradually replace the pages of “Spiders Are Scary” with evidence that they are not, in fact, all that frightening. When you return the book, it has been changed, and the next time it’s checked out (when, for instance, you come across a tarantula in your attic), the fear response will be smaller. In Phelps’ experiments, the effect lasted up to 1 year in people manipulated during their reconsolidation period, and was specific to the stimulus that test subjects were “reminded” of, suggesting a long-lasting and very selective elimination of a fear memory.
It’s not quite “Eternal Sunshine.” As Phelps rightly points out in the Nature video, this is the elimination of an association, not a specific memory of a person, place, or event – you could remove the fear of spiders, but not your awareness that such a thing as spiders exists. But as a relatively simple manipulation of the brain’s library for memory, it’s a treatment that could be a life-saver for people with PTSD or crippling phobias.