Memory and Addiction

David Carr, a media columnist for the New York Times, was addicted to crack for several years in the late 1980's. In the Times Magazine (and in his new book) he tells the story of his own investigation into his junkie years, as he tries to understand how he let a chemical nearly ruin his life. It's a harrowing tale of addiction and love, but a major subplot is the inherent fraudulence of memory:

When memory is called to answer, it often answers back with deception. How is it that almost every warm bar stool contains a hero, a star of his own epic, who is the sum of his amazing stories?

If I said I was a fat thug who beat up women and sold bad coke, would you like my story? What if instead I wrote that I was a recovered addict who obtained sole custody of my twin girls, got us off welfare and raised them by myself, even though I had a little touch of cancer? Now we're talking. Both are equally true, but as a member of a self-interpreting species, one that fights to keep disharmony at a remove, I'm inclined to mention my tenderhearted attentions as a single parent before I get around to the fact that I hit their mother when we were together. We tell ourselves that we lie to protect others, but the self usually comes out looking damn good in the process.

[SNIP]

As a veteran journalist, I decided to report the story. For two years on and off, I pulled medical and legal documents and engaged in a series of interviews with people I used to run with. By turns, it became a kind of journalistic ghost dancing, trying to conjure spirits past, including mine.

In my book, I write about some recent experiments on the reconsolidation of memory that help explain why memories are so often dishonest.

The scientists proved this by conditioning rats to associate a loud noise with a mild, electrical shock. (When it comes to pain, the mind is a quick learner.) As predicted, injecting a chemical that stops new proteins from being created also prevented the rats from creating a fearful memory. Since their brains were unable to connect their context to the electrical shock, the shock was always shocking.

But Nader, Ledoux and Shafe took this simple experiment one step further. First, they made sure that the rats had a strong memory associating the shock with the noise. They wanted rodents that would cower in fear whenever the sound was played. After letting this memory solidify for up to 45 days, they re-exposed the rats to the scary noise and injected a protein inhibitor into their brain. But what made their experiment different was its timing. Instead of interrupting the process of making a memory, they interrupted the process of remembering a memory, injecting the noxious chemical at the exact moment the rats were recalling what the noise meant. According to the dogma of remembrance, nothing much should have happened. The long-term memory should exist independently of its recall, filed away in one of the brain's protected file-cabinets. After the poison is flushed out of their cells, the rats should remember their fear. The noise should still remind them of the shock.

But this isn't what happened. When Nader, et.al. blocked the rats from remembering their fearful memory, the original memory trace also disappeared. After only a single interruption of the recollection process, their fear was erased. The rats became amnesiacs.

At first glance, this experimental observation seems incongruous. After all, we like to think of our memories as being immutable impressions, somehow separate from the act of remembering them. But they aren't. A memory is only as real as the last time you remembered it. The more you remember something, the less accurate the memory becomes.

The Nader experiment, simple as it seems, requires science to completely re-imagine its theories of remembering. It reveals memory as a ceaseless process, not a repository of inert information. It shows us that every time we remember anything, the neuronal structure of the memory is delicately transformed, a process called reconsolidation. (Freud called this process Nachtraglichkeit, or "retroactivity".) The memory is altered in the absence of the original stimulus, becoming less about what you remember and more about you.

Some scientists are now trying to take advantage of memory reconsolidation to erase memories of addiction.