Individuals with hyperthymesia can recall almost every day of their
lives in near perfect detail, as well as public events that hold some
personal significance to them. Those affected describe their memories as
uncontrollable associations, when they encounter a date, they "see" a
vivid depiction of that day in their heads. Recollection occurs without hesitation or conscious effort.
It is important to draw a distinction between those with hyperthymesia and those with other forms of
exceptional memory,
who generally use mnemonic or similar rehearsal strategies to memorise
long strings of subjective information.
Memories recalled by
hyperthymestic individuals tend to be personal, autobiographical
accounts of both significant and mundane events in their lives. This
extensive and highly unusual memory does not derive from the use of
mnemonic strategies; it is encoded involuntarily and retrieved
automatically.
Despite being able to remember the day of the week on which a
particular date fell, hyperthymestics are not calendrical calculators
like some people with autism or savant syndrome. Rather, hyperthymestic recall tends to be constrained to a person's lifetime and is believed to be an unconscious process.
The unique brains of those with Highly Superior Autobiographical Memory (HSAM)
In 2006,
Parker, Cahill and McGaugh reported the first known case of Highly Superior Autobiographical
Memory
(HSAM) in a research participant known as “AJ”. When provided with a
date, AJ could specify on which day of the week it fell and what she did
that day. Since then, more people with this extraordinary ability have
been identified (
click here to view a “60 Minutes” episode on them or
here for another Psychology Today blog post on this), and researchers have now discovered structural
brain differences in people with HSAM compared to people without it (
LePort et al., 2012).
This is especially interesting given that people with HSAM do not show
exceptional memory in other domains besides autobiographical memory.
Among the brain differences that the researchers note is “amplified
white matter tract coherence” (p. 12), which they suggest may indicate
that the transfer of information among connecting neural regions is
enhanced in participants with HSAM and that this may contribute to their
superior autobiographical memories.
As LePort and colleagues point out, however, whether the structural
brain differences that they discovered are a cause of HSAM or the result
of activities that themselves cause HSAM is not yet known.
It
might be easy to jump to the conclusion that people with HSAM are simply
born with brains that differ from normal brains and that innate
structural differences in the brains of people with HSAM are what allow
for their exceptional autobiographical memory abilities. For example,
maybe they are born with enhanced connectivity among brain regions
critical to autobiographical memory.
A more interesting
possibility, however, is that the brain differences (as well as the
remarkable autobiographical memory ability) result from unique
experiences that occur during development.
Experiences themselves cause changes in the brain to take place. For example, it has long been known that
the
brains of rats exposed to an enriching environment during development
differ from those of rats exposed to an impoverished environment—rats in an enriched
environment show increased cortical weight and numbers of glial cells and also show benefits to memory ability.
Research
on musical training is an excellent example of how experiences can
impact the structure of the human brain, as discussed in this
New York Times article and this
Scientific American blog and reviewed
here.
Researchers have known for some time that the brains of musicians
differ from those of non-musicians, but researchers have questioned
whether this is due to innate differences between musicians and
non-musicians. However, recent evidence suggests that musical training
itself contributes to the brain differences between the musically
trained and untrained.
One study showed
that children given 15 months of musical training exhibited structural
changes in their brain relative those that did not. More recently,
researchers at Northwestern showed that neural changes that appear to result from musical training in
childhood persist into adulthood.
If
structural brain differences between the musically-trained and
untrained in adulthood can result from childhood training in that
domain, then what type of experience or training could
potentially underlie the brain differences shown in people with HSAM?
Actress
Marilu Henner, who was one of the participants in the research by McGaugh and colleagues (as shown in this "
60 Minutes" episode), may provide some clues in her
book on
her experience with HSAM and on autobiographical memory. In it, she
describes a pastime of hers during childhood. “I decided to play a
little game with myself, in which I tried to remember every day that had
led up to that moment starting with the most recent
What did I do a week ago? Two weeks ago? Three weeks ago?
I even started to go back to the previous years and the year before
that, remembering specific days from first grade and kindergarten. Over
time, this exercise became not only my routine to fall asleep, but also a
way to mentally challenge and exercise my brain to the point that I
could ‘time-travel’ back to: What did we do each day of our vacation?
What was I doing when I was exactly the day my younger brother Lorin’s
age? My Niece Lizzy’s age?”
It seems plausible that this type of
“training” or memory practice during childhood could lead to structural
changes in the brain that are detectable in adulthood and correlated
with HSAM.
As
McGaugh and colleagues
suggest in their article, future research on children with HSAM might
shed light on this issue. But perhaps an approach similar to that taken
with
recent research on musical training could
be taken as well. Specifically, maybe children could be randomly
assigned to either a no-memory-training control condition or to an
autobiographical memory training condition in which they receive a daily
autobiographical memory training exercise similar to what Marilu Henner
describes in her book. Would structural brain differences be shown 15
months later? If so, would they still be shown in adulthood? Would
characteristics of HSAM be found? This would be an interesting study
indeed.
... from universities, journals, and other research organizations
July 30, 2012 —
UC Irvine
scientists have discovered intriguing differences in the brains and
mental processes of an extraordinary group of people who can
effortlessly recall every moment of their lives since about age 10.
UC Irvine
scientists have discovered intriguing differences in the brains and
mental processes of an extraordinary group of people who can
effortlessly recall every moment of their lives since about age 10.
(Credit: © James Steidl / Fotolia)
The phenomenon of highly superior autobiographical memory -- first
documented in 2006 by UCI neurobiologist James McGaugh and colleagues in
a woman identified as "AJ" -- has been profiled on CBS's "60 Minutes"
and in hundreds of other media outlets. But a new paper in the
peer-reviewed journal Neurobiology of Learning & Memory's July issue offers the first scientific findings about nearly a dozen people with this uncanny ability.
All had variations in nine structures of their brains compared to
those of control subjects, including more robust white matter linking
the middle and front parts. Most of the differences were in areas known
to be linked to autobiographical memory, "so we're getting a
descriptive, coherent story of what's going on," said lead author Aurora
LePort, a doctoral candidate at UCI's Center for the Neurobiology of
Learning & Memory.
Surprisingly, the people with stellar autobiographical memory did not
score higher on routine laboratory memory tests or when asked to use
rote memory aids. Yet when it came to public or private events that
occurred after age 10½, "they were remarkably better at recalling the
details of their lives," said McGaugh, senior author on the new work.
"These are not memory experts across the board. They're 180 degrees
different from the usual memory champions who can memorize pi to a large
degree or other long strings of numbers," LePort noted. "It makes the
project that much more interesting; it really shows we are homing in on a
specific form of memory."
She said interviewing the subjects was "baffling. You give them a
date, and their response is immediate. The day of the week just comes
out of their minds; they don't even think about it. They can do this for
so many dates, and they're 99 percent accurate. It never gets old."
The study also found statistically significant evidence of
obsessive-compulsive tendencies among the group, but the authors do not
yet know if or how this aids recollection. Many of the individuals have
large, minutely catalogued collections of some sort, such as magazines,
videos, shoes, stamps or postcards.
UCI researchers and staff have assessed more than 500 people who
thought they might possess highly superior autobiographical memory and
have confirmed 33 to date, including the 11 in the paper. Another 37 are
strong candidates who will be further tested.
"The next step is that we want to understand the mechanisms behind
the memory," LePort said. "Is it just the brain and the way its
different structures are communicating? Maybe it's genetic; maybe it's
molecular."
McGaugh added: "We're Sherlock Holmeses here. We're searching for clues in a very new area of research."
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Story Source:
The above story is based on materials provided by University of California - Irvine.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
- Aurora K.R. LePort, Aaron T. Mattfeld, Heather Dickinson-Anson,
James H. Fallon, Craig E.L. Stark, Frithjof Kruggel, Larry Cahill, James
L. McGaugh. Behavioral and neuroanatomical investigation of Highly Superior Autobiographical Memory (HSAM). Neurobiology of Learning and Memory, 2012; 98 (1): 78 DOI: 10.1016/j.nlm.2012.05.002
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