Unlocking the secrets of memory

By Bryan Smith

updated 12:36 p.m. ET Oct. 5, 2008

The words on the pink post-it note, thumbtacked to a wall in his home, can't be any clearer: "This house, in Oak Park, Illinois, is where Bob and Donna live." But Bob Berry shakes his head. No. I live in Wichita Falls... don't I? Why, I have an exam tomorrow at my high school.

I've talked to my father about it... or have I? Bob wonders. Lately, he can't be sure of anything. Except the nice woman. The one who always seems to be around, the one with the kind face who now takes his hand. Something about her seems familiar. But what?

"No Bob, you already finished school. Don't you remember?" the woman says.

"Did I?"

"Yes. You were a professor at one of the best colleges in the country — Northwestern University — a Ph.D., a neuroanatomist."

"But my father..."

The woman, Donna Kersey, squeezes his hand. "Your father died, Bob, remember?"

He stares at her blankly. "He did? I just talked to him."

She hates having to tell him — again — but what can she do? Ever since a near-fatal cardiac arrest robbed Bob's brain of precious oxygen for close to 5 minutes, his memory has been like a blackboard swiped clean every few moments — erased. Pieces of information — the time, what day it is, where he lives — dissolve like vapor trails. 

So he has to be reminded that he is not a high-school student in Wichita but a 63-year-old man who is an accomplished brain scientist; that he can't see his father because his father died long ago. And he has to be told that Donna is not his mother, as he has guessed on occasion, but the person he has lived with for 15 years, the woman who rescued him when he nearly died, the woman he loves.

In short, Bob has to be treated like a person in the early stages of the very ailment he devoted his life's work to curing — Alzheimer's disease.

The one consolation is that, unlike the Alzheimer's victims he once studied, Bob will not worsen. He will be spared the agonizing descent into full-blown dementia. But he will never be the same. He will never do the work of a brain scientist, never again author a seminal study, never be able to tap his most powerful resource, the one that might help him help himself: his mind.

That's the conventional thinking, at least. A bolder view, one rooted in a groundswell of intriguing advances in memory research, suggests a different notion: Never say never.

The mystery of memory
Memory has been a source of wonder as far back as recollection itself. The early Egyptians mused on it. The Greeks named a goddess, Mnemosyne, after it. The Roman orator Cicero astonished citizens with his mastery of it. In the centuries that followed, shrinks, scientists, and dreamers have pursued, poeticized, and puzzled over it.

However, until scientists benefited from a succession of breakthroughs in brain mapping — CAT scans and MRIs initially, and diffusion tensor imaging, positron emission tomography (PET) scans, and functional MRI more recently — our understanding of exactly what memory is and how it works was more art than science, the product of guesswork and hunches.

Even now, a definitive explanation of the process eludes us, although here's what researchers believe is happening: First, you experience something. That experience, in turn, converts into a pulse of energy that zips along a network of neurons and lands for a split second in your sensory memory, which is a way station for your immediate impressions. From there, the information — a phone number, say, that you're about to dial — is shunted into short-term memory where it's available for anywhere from a few seconds to a couple of minutes.

After that, a seahorse-shaped brain structure called the amygdala decides if the experience (the number you dialed) should be discarded as nonessential or shuffled along to long-term storage. For the latter option, the brain locks in information based on such factors as the importance of the moment (a first kiss, a childhood trip to the beach, the smell of mom's cooking), the emotion attached to the event (a loved one's death, the joy of a child's birth), or the importance you assign to the information (a Social Security number).

This long-term storage is further broken down into two categories: declarative memory (the recollection of specific events or episodes) and nondeclarative "muscle memory" (skills like riding a bike or driving a stick shift). Many scientists also identify semantic memories, which are factual and unrelated to specific experiences. For example, semantic memory tells you what an omelet is, but not whether you ate an omelet for breakfast that morning.

Explaining just how you retrieve the information — how you pull a name and a face out of the 100 billion or so neurons forged into the trillion-plus possible patterns — is trickier. The best and latest science strongly suggests that your brain activates the same pattern of neurons that was used to store the information. In other words, memory is like an electronic map route that lights up when you want to remember something.

At least that's the nuts-and-bolts explanation. For brain scientists striving to unlock the mystery of memory, the process is much more profound, something spoken about in almost reverential tones — a quest as fundamental and soul-stirring as science has to offer. "Understanding memory is easily the equal of exploring the galaxies," says Howard Eichenbaum, Ph.D., the director of Boston University's center for memory and brain. "It's like figuring out the universe of who we are."

Memory damage
On a muggy Chicago night in 2006, Bob and Donna had just settled down to dinner when Bob, poised over a forkful of green beans, gasped, "Oh, my god," and collapsed face-first into his plate.

Assuming he had suffered a heart attack, Donna raced to call 911. Help arrived quickly, mere minutes after Bob's collapse. Paramedics were able to revive him, but he then slipped into a coma. For weeks, Donna and Bob's family, including his two sons, Robb and Kevin, waited to find out the degree of brain damage he had suffered.

As an Alzheimer's researcher, Bob had witnessed firsthand the devastation of memory loss. And he had made his wishes clear, should he ever find himself in such a predicament.

"He said, 'If I have a chance of regaining brain function, keep me plugged in,'" Donna recalls. "But if I can't use my brain, then don't."

When Bob finally woke up, family members were thrilled to learn that his mind was largely intact. But they also realized that a part of him had been lost. He seemed to recognize Robb and Kevin, but he looked puzzled when he saw Donna. Just how bad his memory had been damaged wasn't immediately clear to anyone, including the doctors. So Robb developed his own primitive exam.

"Hey dad, know any pirate jokes?" he'd ask. Bob would shake his head no. "Pirate walks into a bar with a steering wheel sticking out of his fly. Bartender says, 'Hey buddy, what's with the steering wheel sticking out of your pants?' The pirate says, 'Yar, it's drivin' me nuts!'"

Bob would laugh. Every time. He had no idea that Robb had been telling him the joke nearly every day for weeks. Or that a part of his son cried every time his father laughed.

MORE FROM MENTAL HEALTH

Mental health Section Front

Suicides raise worries about recession’s real cost Chill: A little stress may help you live longer Suicide prevention groups protest ‘The Office’ Tokyo train stations use lights to stem suicides Why memory lane is such a mortifying stroll Kids on psych drugs have alarming weight gain Self-help course may have led to her suicide Study: Working past retirement boosts health Youth driving discussions about suicide Mediterranean diet cuts depression risk Mental health Section Front   Add Mental health headlines to your news reader: