To find out about the latest brain research, 60 Minutes II Correspondent Scott Pelley recently visited Healey and other similar patients at Dr. Antonio Damasio's University of Iowa lab.
When shown pictures of Monica Lewinsky, Michael Jordan and Julia Roberts, Healey doesn't know who any of them are.
Healey, in his late 40s, lives with his parents in Montana. His condition is called global amnesia. His memory is like a tape deck that's recording and erasing at the same time.
He can retain about one minute's worth of new information. Then 60 seconds later, whatever was there is gone.
Damasio's wife Hanna, a doctor in charge of neuroimaging at the lab, says that Healey has lost use of part of his brain: "This particular part is involved in the process of acquiring new knowledge and also in the process of holding that knowledge," she says.
"So you could say that it is involved predominantly in learning and memory," she says.
Through Healey and others like him, Dr. Damasio has learned that memories are not stored all in one place. The brain is much more complex than that. It turns out that different kinds of memories are sorted by type and stored in different locations.
For example, Healey's memories of life before his illness are undamaged because they're recorded in an unaffected part of his brain.
Healey remembers much about his life before the illness. Healey has an unusual view of the world, Damasio says: "(He) view(s) it as a world that is happening right now; it's an ever-present present," he says.
His life is no longer anchored by memory; experiences wash over him and simply flow away. One of Damasio's surprising discoveries is that the brain is not organized in the logical way one might expect. The brain separates memories and skills that seem inseparable.
Take the case of Scott Klett of Iowa City, a supermarket manager, also in his 40s, who became Dr. Damasio's patient without warning.
One recent June, Klett was washing his car when he began to feel dizzy. He had a stroke, which had damaged part of his brain. His wife took him to the hospital.
Klett suddenly realized that he couldn't read. He could recognize letters, but he couldn't read.
He found that he could still write, however: "I was able to pick up a note pad and make notes," he says. "And they were fine. And then two minutes later, I couldn't read what I had written."
Klett was able to write because memory skills are stored in different regions of the brain, just as items in a supermarket are in different aisles. Scott's stroke bypassed the regions necessary for writing, but damaged those controlling reading skills.
By studying the brain, Dr. Damasio hafound that memory is essential to everything that makes people human. His recent book, The Feeling of What Happens, explores the relationship between consciousness, memory and emotion.
Healey illustrates this complex relation. Because he cannot remember, he cannot hold a grudge.
"To feel a grudge, you need to recall constantly that a certain person has done something that you did not approve of," Damasio says. "And that, of course, requires a memory being systematically, consistently reactivated. And he cannot do that."
Tom Cole serves as another example. A playwright, he recently experienced a sudden failure of memory that eventually sent him to the hospital.
"It's a loss of confidence," Cole says. "I used to feel I had a very good memory. I was quick, and I could balance huge amounts of research material in my head. Perhaps I still can. But I don't believe it anymore."
One day, Cole was jogging in the Connecticut woods when an eerie feeling came over him. He realized he couldn't remember the names of anyone he knew - even those of his wife and daughter. It was a very disturbing experience.
"He actually lost his sense of self," Damasio says. "He was not Tom complete. Let's put it this way. At least, he didn't know that he was Tom."
In other words, Cole lost consciousness, even though he was standing and appeared awake. For a moment this sense of who he was vanished, while the rest of his brain and body carried on.
Use of magnetic resonance imaging is the first step in discovering what happened inside Cole's head, via a three-dimensional picture of his brain. If a tumor or a stroke disturbed his memory, the evidence will appear on the scan.
Dr. Damasio did an MRI of Cole's brain, and found that there seemed to be no damage. So what happened? The detective work continues as he was wiring and monitored for a 24-hour period, in effect, putting his brain waves on around-the-clock surveillance.
If Cole had a seizure, it could show up in the EEG. Dr. Damasio suspected that light flashing through the leaves as Cole was jogging might have caused a seizure, so he decided to reproduce the experience by flashing strobe lights while Cole was hooked up to an EEG machine.
The goal was to produce a seizure, if possible, in a setting where it could be measured.
Cole did have a seizure - not on the treadmill, but later, when he was asleep. Fortunately, it was a "minimal abnormality," Damasio says.
Now Cole is taking medication to prevent further seizures. His memory has returned and he is almost feeling completely better.
What about Klett, whose stroke left him able to write but not able to read? He couldn't even make sense of the sign above the store where he had worked for 15 years.
Then one morning, the letters fell into place. "It was a banner day in my life. I want to tell you," Klett says. The damaged area, in essence, came back tlife, repaired itself, Damasio says.
Although Damasio's research is driven by his curiosity about human nature, it also has practical benefits.
"The more we know about how emotions are processed in the human brain, the more we will be able to treat effectively disorders such as depression and mania. The more we will be able to cope with pain management," Damasio says.
In Healey's case, though, the brain damage has left him permanently impaired. But it hasn't affected his attitude. When he wants to remember something, he writes it down in a notebook: bowling scores, names, sometimes even jokes.
"Man's lying back in the bed," he says. "There's a cot in (the) doctor's office. And he says, 'Doctor, you got to help me. I've got a terrible problem.'"
"'Well, what's wrong sir?'"
"He says, 'I snore so loudly I wake myself up.' "
"And the doctor says, 'Well, I advise you to sleep in another room,'" he concludes.
Healey, who says that he is a happy man, laughs. The joke is as funny as the first time he heard it.
Produced by David Kohn;