Eternal sunshine of the partially-wiped mind

Memory — lost, repressed, manufactured, or recovered — has long been a dependable subject for movies and television shows. I can’t remember how many soap operas and melodramas have trundled out the old amnesia plot to keep the audience hooked. You know, the one where two people are madly in love, but days before the wedding the guy gets conked on the head and can’t remember the love of his life.

In the last decade, Christopher Nolan (The Dark Knight) gave us a protagonist whose search for his wife’s killers was seriously hampered by his inability to form new memories. To help himself remember, he took a lot of Polaroids, wrote information on Post-Its, and tattooed the really important details onto his body.

The heroine of the Adam Sandler movie Fifty First Dates suffers a head injury that causes her to relive the same day over and over again. It sounds like a wacky premise for a romantic comedy, except that there have been many such cases reported by neurologists such as Oliver Sacks in his book, The Man Who Mistook His Wife For A Hat.

Eternal Sunshine of the Spotless Mind features a sleazy doctor who offers a procedure for erasing unwanted memories. The unhappy lovers played by Jim Carrey and Kate Winslet decide that it is not enough for them to break up, they must forget each other completely. Carrey goes for the procedure, only to decide that he doesn’t want to erase the memory of their love after all. There’s a funny, heart-rending sequence in which Carrey tries to conceal his memories of Winslet under his childhood recollections.

Eternal Sunshine was another invention of screenwriter Charlie Kaufman, who had previously offered us tours of John Malkovich’s mind. It was clever, but too far out and unlikely to happen in real life.

That was a couple of years ago. Today research in neuroscience is bringing the far-out much closer to the plausible. According to Benedict Carey in the New York Times, it may soon be possible to edit human memory by controlling a single substance in the brain. Imagine being able to forget your fear of flying, or your addiction to tranquilizers, or that outfit you wore to the junior-senior prom in the 1980s. How can it be done?

For starters, neuroscientists are close to figuring out how your brain stores memories. How exactly do you remember your email password, the smell of fabric softener, or where you put your spare key? Since the ‘60s researchers have believed that the brain cells triggered by a specific experience have a kind of speed-dial connection to each other. If one is activated, the others are immediately alerted, and each adds a detail of sight, smell, texture, etc. How does the brain do this?

Ten years ago, Doctors Lichtman and Sanes made a list of 117 molecules involved in this type of speed-dial connection. Recently a team led by Dr. Todd Sacktor of the SUNY Downstate Medical Center in Brooklyn found that the molecule called PKMzeta was present and activated in cells when they were ‘speed-dialed’ by their fellows. PKMzeta molecules arrange themselves into the connections between the cells, and stay there indefinitely.

Meanwhile, Dr. Andre Fenton, also of SUNY Downstate, has been researching spatial memory in mice. He has learned how to develop their memories for where things are located. Fenton has discovered that when a drug called ZIP—which interferes with PKMzeta — is injected into the brains of these mice, they almost instantly forget everything they’ve been taught.

Interestingly enough, another movie written by Charlie Kaufman, Human Nature, features a scientist who is teaching mice table manners. Have neuroscientists been taking their cues from Kaufman?

Of course, there are major ethical issues surrounding the possibility of memory-editing. On one hand, it could help people to deal with traumatic memories and addictions. Research into PKMzeta could benefit people with Alzheimer’s disease, dementia, and memory loss related to aging.

On the other hand, if memories of bad behavior and criminal acts are erased, how would we exact justice? Conscience—the sense of right and wrong—springs from our fear and anxiety at the evil we humans are capable of. If our memories of the things that bother us can be wiped clean, what would we do for a conscience? In short, does forgetting make everything okay?

We’re just beginning to figure out how our brains work.

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