What Scientists Learned From The World's Most Famous Amnesiac

Kent Cochrane, a man with one of the most studied brains in history, died this year at the age of 62, leaving scientists with a far greater understanding of the complex workings of the memory.

After a motorcycle accident in 1981, then 30-year-old Cochrane -- popularly known as "K.C." -- developed neurological damage that resulted in extremely rare forms of amnesia. He completely lost his hippocampus, a part of the brain thought to be critical for memory, and he was left unable to recall past events or imagine future events.

But Cochrane surprised doctors by being able to remember certain things. Although his personal memories were gone, he could still recall "semantic memories" -- those without emotional tone or context.

For example, he would remember people he knew, like his parents and friends from the past, but he wouldn't be able to recall any details relating to those people or any specific times that they had spent together. He could also remember the fact that he had graduated from high school, but he couldn't remember what his high school graduation was like.

The study of Cochrane's brain completely shifted the way that we think about memory. If he could indeed remember certain facts even without his hippocampus, then memory, at least in some cases, must be able to bypass this part of the brain.

This week, Shayna Rosenbaum, a researcher at the Cognitive Neuroscience Lab at York University in Toronto, who worked with Cochrane, joined NPR's "All Things Considered" to revisit the impact of research conducted on his brain. On the show, Rosenbaum explained that the hippocampus, which is responsible for creating new memories and maintaining old ones, is vulnerable to a number of neurological disorders in addition to head injury, including Alzheimer's and epilepsy.

"So many people, unfortunately, suffer from certain forms of memory loss," she told NPR. "But what we've learned is that not all forms of memory are affected, so memory is not just one thing. And we've learned from cases like K.C. that patients can, in fact, rely on the types of memories that are spared, such as memory for facts about the world and about oneself in order to compensate for those aspects that are impaired."

In a study published in 2007, Rosenbaum also found that, contrary to previous belief, memory impairment does not seem to have any effect on a subject's ability to take on another person's perspective (what's known in psychology as "theory of mind"). After his accident, Cochrane could still comfortably interact with people and was easily able to read their emotional states, the research showed.

According to Rosenbaum, before he passed away, Cochrane did have some awareness of the impact his case had on scientific research.

"When we drew his attention to the many contributions that he had made to our understanding of memory, he himself was blown away," she said. "He really did seem to appreciate the types of contributions that this made to our understanding of memory."