Beyond extreme examples, sometimes close to the pathology, there are happy hypermnesics.
In his new Funes or memory, Jorge Luis Borges evokes the memory of Irénée Funes, an Indian from Uruguay who, after a horse accident, finds himself endowed with a phenomenal, invasive memory. A curse. "My memory, sir, is like a pile of junk"said Funes. Through the infinite reflections of his kaleidoscopic memory, he perceives only fragments of the world, whose meaning he loses. Because " think, writes Borges, it is to forget differences, to generalize, to abstract.
Funes echoes a very real hypermnesic, studied by the Russian psychologist Alexander Luria, the journalist Solomon Cherechevski, aka Veniamin or S. He also had a memory eidetic, which allowed him to remember tables of numbers, letters or words that he could return without error fifteen years later. Synesthete, he associated these items with particular shapes, colors or textures, which facilitated their recall. But he was unable to extract categories, such as birds or liquids. Apart from his memory exploits, he was considered slow-witted.
20,000 decimals of pi
Closer to home, the American Kim Peek (1951-2009), who served as a model for the film Rain Man and had several brain malformations, was also embarrassed by a phenomenal memory. We could also mention the British Daniel Tammet, synesthete and diagnosed as autistic Asperger, able to retain more than 20,000 decimals pi and learn a new language in a few weeks. Or the American Jill Price, evoking precisely the least detail of her past life, whose "case" led to define in 2006, a syndrome of hypertrophy of episodic memory – while his working memory is average. She says she suffers from having to relive painful episodes of her existence.
Several hypotheses are advanced to explain these hypermnesias. One case, HK, studied at Vanderbilt University (Tennessee), points to a closer connection between the hippocampus, essential in memory, and the amygdala, which regulates emotions. Other observations, conducted at the University of California at Irvine, emphasize the role of the temporal lobe and the strengthening of a beam connecting it to the frontal lobe in the case of a highly superior autobiographical memory. Some also mention sometimes a poor management of forgetfulness, in connection with some proteins regulating the long-term memory, some of which are involved in the return of obsessive memories related to post-traumatic stress disorder.