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April 24, 2015

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Brain glitch causes people to live “in the third person”

April 24, 2015
Courtesy of the Baycrest Centre 
for Geriatric Care
and World Science staff

A new study ex­plores a brain glitch that sci­en­tists say causes peo­ple to live life in the “third per­son.”

Peo­ple with the con­di­tion can’t re­call hav­ing per­son­ally lived the events in their lives, but oth­er­wise en­joy nor­mal learn­ing, mem­o­ry and func­tion­ing, ac­cord­ing to sci­en­tists. The con­di­tion, called life­long se­verely de­fi­cient au­to­bio­graph­i­cal mem­o­ry or SDAM, does­n’t stop peo­ple from learn­ing about past episodes in their lives or re­cit­ing and us­ing the in­forma­t­ion. They just can’t feel them­selves in those past situa­t­ions.

In new stu­dy, sci­en­tists at the Bay­crest Cen­tre for Ger­i­at­ric Care in To­ron­to ex­am­ined three mid­dle-aged vol­un­teers with the syn­drome. Two from the Un­ited States and one from the Un­ited King­dom.

While sci­en­tists don’t know how rare the con­di­tion is, the Ca­na­di­an re­search­ers de­scribed thier study as the first op­por­tun­ity to ex­am­ine the syn­drome in healthy peo­ple in a lab with brain im­ag­ing avail­a­ble as well as re­li­a­ble mem­o­ry test­ing pro­ce­dures.

The find­ings are posted on­line ahead of print in the research jour­nal Neu­ropsy­cholo­gia.

“Many of us can re­late to the idea that peo­ple have dif­fer­ent abil­i­ties when re­mem­ber­ing events. What is un­ique about these in­di­vid­u­als is that they have no per­son­al rec­ol­lec­tion,” said Bri­an Le­vine, sen­ior sci­ent­ist at the in­sti­tute and sen­ior au­thor of the pa­per.

“Even though they can learn and re­call in­forma­t­ion nor­mally and hold down pro­fes­sion­al ca­reers, they can­not re-experience the past with a viv­id sense of per­son­al re­liv­ing. It’s as if their past was ex­pe­ri­enced in the third per­son.”

There is no his­to­ry of am­ne­sia, brain in­ju­ry, birth com­plica­t­ions, seizures, stroke, neu­ro­lo­g­i­cal dis­ease, or psy­cho­log­i­cal dis­or­der to ex­plain their mem­o­ry syn­drome, he added. The pa­tients are well-ed­u­cat­ed.

Us­ing dif­fer­ent meth­ods of brain im­ag­ing, the team found ev­i­dence of brain dif­fer­ences in the SDAM cases com­pared to other volun­teers. The re­search­ers al­so ex­am­ined the size of the hip­po­cam­pus, a brain re­gion known to play a crit­i­cal role in rec­ol­lect­ing events, and found a sub­tle size re­duc­tion in the right hip­po­cam­pus in the SDAM cases.

When pre­sented with events from their own life, the SDAM cases showed re­duced ac­tiva­t­ion in cer­tain brain re­gions that play a prom­i­nent role in au­to­bio­graph­i­cal mem­o­ry pro­cesses, such as “men­tal time trav­el,” the in­ves­ti­ga­tors said.

When their mem­o­ry for pic­tures was tested, the elec­tri­cal brain sig­nals as­so­ci­at­ed with con­scious rec­ol­lec­tion in healthy adults were greatly re­duced in the SDAM cases, though their rec­og­ni­tion was nor­mal, ac­cord­ing to the stu­dy.

“The SDAM cases had very lit­tle ac­cess to au­to­bio­graph­i­cal de­tails from their re­mote past, in­clud­ing vis­u­al­iz­a­tion of those ex­pe­ri­ences and their emo­tion­al state,” said Dan­iela Palombo, the stu­dy’s lead au­thor and cur­rently a post-doctoral re­search­er at VA Bos­ton Health­care Sys­tem and Bos­ton Uni­vers­ity School of Med­i­cine.

The SDAM cases in­stead rely on “non-recollective mem­o­ry,” such as re­hearsed fac­tu­al knowl­edge about them­selves or oth­ers, ac­cord­ing to Palombo and col­leagues. “There is a lot that we can ac­com­plish with these skills,” said Le­vine, and the syn­drome may in­volve a life­time of com­pensa­t­ion us­ing these abil­i­ties.

Palombo said fur­ther stud­ies are needed to tease out oth­er pos­si­ble neu­ro­lo­g­i­cal fac­tors and health is­sues that may play a role in SDAM. The sci­en­tists said the con­di­tion is the ex­treme op­po­site of anoth­er syn­drome known as highly su­pe­ri­or au­to­bio­graph­i­cal mem­o­ry, or HSAM, which in­volves an un­can­ny abil­ity to re­call vast amounts of de­tail about past life events.


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A new study explores a brain glitch that scientists say causes people to live life in the “third person.” People with the condition can’t recall having personally lived the events in their lives, but otherwise enjoy normal learning, memory and functioning, according to scientists. The condition, called lifelong severely deficient autobiographical memory or SDAM, doesn’t stop people from learning about past episodes in their lives or reciting and using the information. They just can’t feel themselves in those past situations. In new study, scientists at the Baycrest Centre for Geriatric Care in Toronto examined three middle-aged volunteers with the syndrome. Two from the United States and one from the United Kingdom. While scientists don’t know how rare the condition is, the Canadian researchers described thier study as the first opportunity to examine the syndrome in healthy people in a lab with brain imaging available as well as reliable memory testing procedures. The findings are posted online ahead of print in the journal Neuropsychologia. “Many of us can relate to the idea that people have different abilities when remembering events. What is unique about these individuals is that they have no personal recollection,” said Brian Levine, senior scientist at the institute and senior author of the paper. “Even though they can learn and recall information normally and hold down professional careers, they cannot re-experience the past with a vivid sense of personal reliving. It’s as if their past was experienced in the third person.” There is no history of amnesia, brain injury, birth complications, seizures, stroke, neurological disease, or psychological disorder to explain their memory syndrome, he added. The patients are well-educated. Using different methods of brain imaging, the team found evidence of brain differences in the SDAM cases compared to normal subjects. The researchers also examined the size of the hippocampus, a brain region known to play a critical role in recollecting events, and found a subtle size reduction in the right hippocampus in the SDAM cases. When presented with events from their own life, the SDAM cases showed reduced activation in certain brain regions that play a prominent role in autobiographical memory processes, such as “mental time travel,” the investigators said. When their memory for pictures was tested, the electrical brain signals associated with conscious recollection in healthy adults were greatly reduced in the SDAM cases, though their recognition was normal, according to the study. “The SDAM cases had very little access to autobiographical details from their remote past, including visualization of those experiences and their emotional state,” said Daniela Palombo, the study’s lead author and currently a post-doctoral researcher at VA Boston Healthcare System and Boston University School of Medicine. The SDAM cases instead rely on “non-recollective memory,” such as rehearsed factual knowledge about themselves or others, according to Palombo and colleagues. “There is a lot that we can accomplish with these skills,” said Levine, and the syndrome may involve a lifetime of compensation using these abilities. Palombo said further studies are needed to tease out other possible neurological factors and health issues that may play a role in SDAM. The scientists said the condition is the extreme opposite of another syndrome known as highly superior autobiographical memory, or HSAM, which involves an uncanny ability to recall vast amounts of detail about past personal events.