They are people with "highly superior autobiographical memories," and UC Irvine researchers so far have found at least 22 -- and possibly as many as 32 subjects in this country alone -- who can remember with extraordinary accuracy and in extraordinary detail the events of their lives and the days on which they occurred.
Society for Neuroscience's annual meeting, UC Irvine researcher Aurora Leport offered new insights into people with this remarkable talent, suggesting their brains are structured differently than they are in those of us who can't remember what we ate for lunch yesterday. Those structural differences may account not only for their curious quirk of memory, but for some other quirks as well.
It turns out that memories are not the only things these unusual people collect: a tendancy toward obsessive-compulsive behaviors, including hoarding and germophobia -- is another common feature among those with highly-superior autobiographical memory, Leport says.
And when Leport and her colleagues put 11 of their subjects into a magnetic brain imaging scanner, they found that two areas of their brains -- the middle temporal gyrus and the basal ganglia -- were larger than those of people who showed no sign of superior autobiographical memory. Those same areas, it turns out, also are enlarged in people who suffer from obsessive compulsive disorder.
"Their obsession about their life memories and their need to organize those memories by the dates on which they occurred suggest that their superior memory ability and their obsessive behavior may have some common neurobiological bases," Leport said. While members of the group almost uniformly exhibited "obsessive traits," Leport underscored that none have been diagnosed with OCD.
Leport and her colleagues hope to glean things about normal memory processes from these personal memory champions, including how we store autobiographical memories (for instance, by date only, by reference to some personal interest, or thematically?) and whether some memories -- those with strong emotional content, for instance -- are better retained than others. They are also exploring thegenetic basis for this special talent -- suggested, Leport said in an interview, by the many subjects coming forward who also recall family members with similarly full personal memory banks.
Some potential study subjects have been brought to researchers' attention by their parents, because they are still very young. And yet, they appear to possess extraordinary memory of things that have happened even in their short lives. That, Leport says, does suggest that such memory champions are born that way, not created by training.
Leport said she and her colleagues have been amazed at how many people with high-superior autobiographical memory have come forward since the UC Irvine first presented a case study of one woman -- given the pseudonym A.J. -- was published in 2006. The UC Irvine team, working under the leadership of memory pioneers James McGaugh and Larry Cahill, have spent several years confirming the accuracy of those memories (checking them against calendars, newspaper accounts and personal diaries in many cases) and characterizing this unique population -- most of whom noticed they had an unusual talent around the age of 11 or 12, according to Leport.
When UC Irvine researchers were contacted by a woman who complained of an autobiographical memory that never purged any detail -- the woman who became known as A.J. in medical literature circles -- "we thought this was a one-person case study—an amazing one—and then we were done," Leport said. As the group's research has gained media attention, she added, people have come forward from distant corners of the world saying they, too, have full mental records of every detail of their personal experiences.
Another curiosity about members of this curious group: They are otherwise relatively normal. Their short-term memory is not notably better than that of control subjects of similar sex and age, for instance. They are neither more nor less prone to anxiety or depression than peers with normal memory, and their IQs are about the same. And though those who have come forward are an interesting and largely personable group -- a famous actress (Marilu Henner), a TV producer, newscaster, concert violinist, a history professor, a psychologist -- they are otherwise unremarkable.
Perhaps most surprising to researchers is that these people do not appear to pay for their extraordinary personal databases with sacrifices in other intellectual areas. Leport said that among the subjects who have come forward, none appears to suffer autism-like deficits in social function. This has begun to paint a very different picture of those with extraordinary autobiographical memory than that suggested by the Russian researcher A.R. Luria, who early in the last century presenteda case study of a newspaper reporter he identified only as S., who was so overwhelmed by the extent of his memory's capacity that he had lost any ability to make sense of it all.
"They have great conversational skills, they're very personable, very up and happy; behaviorally they really seem normal," Leport said. "That’s what makes them so interesting and intriguing: You’ve got this superior ability with no deficit."