My memory has ruled my life,” a singular 34-year-old woman told some researchers a couple of decades ago as they sat chatting in their University of California, Irvine, lab. Known as the human calendar to her friends but nicknamed AJ in later research reports, the woman had written to them in distress. She was looking for help. “I want to know why I remember everything,” she said. AJ told the scientists that she couldn’t turn her memory off, even when she was engaged in other activities that demanded her attention, like talking to a friend. “It’s like a running movie that never stops.”
Previous cases of superior memory had generally involved an individual’s ability to remember and rattle off long lists of meaningless information, such as words or digits, as opposed to personal recollections. So the team of scientists ran AJ through a battery of tests. They found that she was indeed able to effortlessly reel off the details of clear and verifiable memories for numerous dates and that her scores were off the charts on standardized and informal autobiographical memory tasks.
The scientists reported on AJ’s condition, and coined the term “hyperthymesia” to describe it, in Neurocase in 2006. Since that time, researchers have documented at least 100 cases of hyperthymesia in the literature. Almost uniformly, those who have the condition find the memories—which tend to be carefully indexed by date—intrusive, uncontrollable, and distressing.
Which is why the recently published case study of a 17-year-old girl dubbed TL is commanding attention. Like others with hyperthymesia, TL has an exceptionally intense and vivid memory for the events that have occurred over her short life. She can provide an especially rich amount of perceptual, spatial, and temporal information, and even recall events from multiple points of view. But unlike the others, she is able to organize these memories into a kind of “memory palace,” and can access them whenever she likes. Most of the memories, she says, are filed in “binders,” according to theme and date and stored in a place she calls “the white room.”
Other rooms in her palace include a “pack ice” room, which she uses to cope with anger; a “problems” room, where she can reflect on challenging situations; and a “military” room, which appeared when her father joined the army. For the most part, she does not find recalling her personal past in this way upsetting. Scientists from the Paris Brain Institute and Paris Cité University recently published an account of TL’s unique condition in the journal Neurocase.
The French scientists tested not only TL’s ability to remember the past but her ability to imagine the future and found she excelled at both. They hypothesized that her ability to control her memories about the past, and to cope with how readily available those memories are, may be at least partially related to her ability to so vividly imagine the future—to time travel. Even for average folks, autobiographical memory is generally associated with a type of consciousness known as “autonoetic,” which not only allows us to relive past events but project ourselves into imaginary situations.
Some studies suggest that hyperthymesia may involve an overactivation of brain networks involved in autobiographical memory and in certain visual tasks. But so far, scientists have not identified any neuroanatomical differences between hyperthymesics and individuals with normal memory. Hyperthymesia may also be linked to synesthesia, said Laurent Cohen, neurologist and co-head of the PICNIC Lab at the Paris Brain Institute who co-authored the case study, in a statement. TL does not have synesthesia, a neurological condition in which sensory processing often involves at least two senses at once—people hear colors or taste sounds—but many of her family members do.
Cohen and her colleague Valentina La Corte, a research professor at the Memory, Brain, and Cognition Laboratory at Paris Cité University, who assessed TL together, have many remaining questions: Does aging affect the memories of hyperthymesics? Can people like AJ or TL learn to control their accumulations of memories? “Everything remains to be discovered,” said La Corte. 
Lead image: Jorm Sangsorn / Shutterstock
