It may not be long before drugs such as ampakines begin to reach the market; when they do, they could have an enormous impact on society. Though the pharmaceutical companies are searching for therapeutic treatments to stave off Alzheimer's and combat dementia, it seems inevitable that their pills will end up in the hands of students cramming for exams and probably a whole lot of other people who just want to enhance their brains. Already psycho-stimulants designed to treat ADHD, like Adderall and Ritalin, are used as "study buddies" by as many as one in four students at some colleges trying to increase their concentration and improve their memories.

All of this raises some troubling ethical questions. Would we choose to live in a society where people have vastly better memories? In fact, what would it even mean to have a better memory? Would it mean remembering things only exactly as they happened, free from the revisions and exaggerations that our mind naturally creates? Would it mean having a memory that forgets traumas? Would it mean having a memory that remembers only those things we want it to remember? Would it mean becoming AJ?

I want to see EP's unconscious, nondeclarative memory at work, so I ask him if he's interested in taking me on a walk around his neighborhood. He says, "not really," so I wait and ask him again a couple minutes later. This time he agrees. We walk out the front door into the high afternoon sun and turn right. I ask EP why we're not turning to the left instead.

"I'd just rather not go that way. This is just the way I go. I don't know why," he says.

If I asked him to draw a map of the route he takes at least three times a day, he'd never be able to do it. He doesn't even know his own address, or (almost as improbably for someone from San Diego) which way the ocean is. But after so many years of taking the same walk, the journey has etched itself on his unconscious. His wife, Beverly, now lets him go out alone, even though a single wrong turn would leave him completely lost. Sometimes he comes back from his walks with objects he's picked up along the way: a stack of round stones, a puppy, somebody's wallet. He's never able to explain how they came into his possession.