In his magnum opus, In Search of Lost Time, Marcel Proust wrote that “remembrance of things past is not necessarily the remembrance of things as they were.” That elegant line speaks to a simple truth: There are things you remember, and there are things you remember well. Even if you can recall a past event, your memories will vary considerably in how much detail they contain, and how correct those details are.
In an elegant experiment, a team of neuroscientists led by Jon Simons at the University of Cambridge have shown that these aspects of our memories—our success at recalling them, their precision, and their vividness—depend on three different parts of the brain.
One of these is the hippocampus—the little, seahorse-shaped area in the middle of the brain that has been most famously associated with memory. In 1953, a neurosurgeon named William Beecher Scoville removed the hippocampus from an epileptic patient named Henry Molaison, robbing him of many past memories of events and preventing him from making any new ones. Molaison became known as Patient HM, and his mental woes enshrined the hippocampus as “the seat of memory.”
It doesn’t act alone. Through brain-scanning studies, scientists have uncovered a network of regions involved in remembering what happened to us—the hippocampus, yes, but also regions further back in the brain, like the angular gyrus and precuneus. When volunteers try to bring up old memories, these areas all start buzzing together.