For most people, it is impossible to remember every single day of one’s existence, although many remember accurately events with high emotional content, (weddings, the birth of a child, the first kiss, the death of a dear one). So-called “normal” days are usually forgotten. However, a very small number of people can recall with extraordinary precision even the dullest day: these individuals have “Highly superior autobiographical memory” (HSAM), and for the first time they have been studied with functional MRI (fMRI), in the attempt to unravel the neurobiological mechanisms underlying the ability to recall an abnormally vast number of lifetime experiences.

The study was performed in Rome in the Fondazione Santa Lucia IRCCS laboratories under the supervision of Drs. Valerio Santangelo, Simone Macrì and Patrizia Campolongo and published on the prestigious journal Proceedings of the National Academy of Sciences of the United States of America (PNAS). The study stems from a fruitful collaboration between several research centres (the Italian Institute of Health, the University of Perugia, the University “Sapienza” of Rome and Irvine University, California, USA).

“We studied eight people with HSAM selected within a group of Italians since 2015, and 21 subjects with normal memory as controls” states the first author Valerio Santangelo, from The University of Perugia and the Fondazione Santa Lucia IRCCS. Not only could they remember the exact date and day of the week of something happened in the past, such as Wednesday 3^rdof August 2011, they could also recall the clothes they were wearing what they had for lunch, which movie they watched, and so on. Even more surprising is the complete lack of effort in remembering events that had occurred decades before.” 

During the fMRI scans, subjects were asked to recall recent or long-passed autobiographic events, such as “the last time you were on a train” or “the first time you kissed someone”, respectively. Within 30 seconds, subjects could press a button to indicate that they had traced the memory, and where then asked to continue “reliving” it in detail. 

“As expected”, states the papers’s last author, Dr. Patrizia Campolungo from the Santa Lucia Foundation and the University of Rome La Sapienza, individuals with HSAM recalled a higher number of vivid details compared to control, subjects. Surprisingly, the main differences between subjects with HSAM were confined to the phase of access to autobiographical memories, and not to its processing in the “reliving” phase. In the access phase, subjects with HSAM showed higher activation of the prefrontal cortex and of its functional connectivity with the hippocampus, particularly ion the case of memories from the distant past.  These results suggest that hypermemory consists mainly in the ability to access, through the prefrontal/hippocampal circuitry, memories which are not accessible to control individuals.”  

These results contribute to open new avenues of research in the field of memory research, which usually investigates diseases where memory deteriorates. “Understanding the neurobiological patterns associated with hyper-mnemonists – says Simone Macrì from the Italian Institute of Health – is crucial to learn how to intervene to reestablish an adequate functioning of memory in pathological conditions”. 

The research team is going to continue looking at people with the superior memory in the Italian population by proposing ad hoc tests by phone in which the subjects must answer questions related to public events dated many years before. 

References:

Enhanced Brain Activity Associated with Memory Access in Highly Superior Autobiographical Memory - Valerio Santangelo, Clarissa Cavallina, Paola Colucci, Alessia Santori, Simone Macrì, James L. McGaugh and Patrizia Campolongo - PNAS July 9, 2018. 201802730; published ahead of print: July 9, 2018. https://doi.org/10.1073/pnas.1802730115

For further information

Patrizia Campolongo
"Vittorio Erspamer" Department of Physiology and Pharmacology, Sapienza University
patrizia.campolongo@uniroma1.it