All in Your Head? Why Some Memories Last a Lifetime

When researchers met a woman with amnesia named Lonni Sue Johnson, they were astonished by her. It was not so much what she could no longer remember, but the things she could not forget. Johnson is still unable to recall her own wedding day but she can tell you how to fly a plane.

In 2007, viral encephalitis destroyed her hippocampus, a brain region that encodes new memories and retrieves old ones. The infection left her with severe retrograde amnesia, an inability to remember events that occurred before her illness. Prior to the onset of amnesia, she was a licensed pilot, an accomplished violist, and a professional artist, having created six covers for the New Yorker and contributed illustrations to more than 50 books. She can no longer recognize famous pieces of music, but she knows how to produce a harmonic on a viola.

“One of the most-striking things about her is that she retained a lot of knowledge about areas in which she had long-lived expertise,” says Dr. Barbara Landau, professor of cognitive science and neuroscience at Johns Hopkins University. The background knowledge has vanished, but she holds on to technical details. “She could tell us things like how to bow a viola and which brushes are used to achieve certain effects on paper.”

Nearly a decade later, her case continues to puzzle researchers. Johnson hasn’t driven a car, flown an airplane, or painted in years, and only occasionally plays music. Yet, she is surprisingly articulate and full of information about her pre-illness capabilities. Her odd pattern of what she can recall defies conventional thinking about memory.

Researchers have long believed that two different long-term memory systems are at work in the brain when we learn a skill. One is declarative, enabling you to remember general facts about the world or your personal history; the other is non-declarative or procedural, also known as muscle memory. Procedural memory, such as learning how to ride a bike or tie your shoes, doesn’t rely on conscious recall. Once you’ve learned how to do those things, they become habit.

Johnson challenges that divide. Landau has worked with her for years and published a series of articles exploring her cognitive capabilities. In a recent paper, she suggests that Johnson’s abilities may even point to a new type of memory. Could there be a blended form of memory that has gone unnoticed?

Storage Space

To some extent, Johnson’s case parallels that of Henry Molaison, a patient known widely as H.M. After surgeons removed his hippocampus to stop recurring seizures, H.M. lost his ability to form new memories. His experiences informed much of what we know about memory, including the role of the hippocampus.

“The hippocampus hooks pieces of information together,” says memory expert Dr. Lynn Nadel, professor of psychology and cognitive science at the University of Arizona. It sorts the pieces and “links and retains connections between them over time.” Without a hippocampus, you might still learn, but you won’t remember.

Johnson presents a perplexing contradiction. In a study that Landau participated in, Johnson was unable to recognize basic statistical patterns, performing worse than a young child. Yet she can learn new music, a technical feat requiring specific knowledge of music that should be out of her reach. H.M., too, had unusual capabilities. He didn’t recognize his own grandchildren, but he could learn procedural skills such as drawing. When researchers gave him a tricky drawing task, he improved on later attempts, despite having forgotten that he had already taken the test.

Landau believes that Johnson’s predicament could point toward a special category within declarative knowledge. Perhaps there is a certain type of factual knowledge, one that is more closely intertwined with skills.