Why some words may be more memorable than others
Our brains use internet search engine strategies to remember words and memories of past experiences

Date:
June 29, 2020
Source:
NIH/National Institute of Neurological Disorders and Stroke
Summary:
In a recent study of epilepsy patients and healthy volunteers,
researchers found that our brains may withdraw some common words,
like ''pig,'' ''tank,'' and ''door,'' much more often than others,
including ''cat,'' ''street,'' and ''stair.'' By combining memory
tests, brain wave recordings, and surveys of billions of words
published in books, news articles and internet encyclopedia pages,
the researchers not only showed how our brains may recall words
but also memories of our past experiences.



FULL STORY ========================================================================== Thousands of words, big and small, are crammed inside our memory banks
just waiting to be swiftly withdrawn and strung into sentences. In
a recent study of epilepsy patients and healthy volunteers, National
Institutes of Health researchers found that our brains may withdraw some
common words, like "pig," "tank," and "door," much more often than others, including "cat," "street," and "stair." By combining memory tests, brain
wave recordings, and surveys of billions of words published in books, news articles and internet encyclopedia pages, the researchers not only showed
how our brains may recall words but also memories of our past experiences.


==========================================================================
"We found that some words are much more memorable than others. Our results support the idea that our memories are wired into neural networks and
that our brains search for these memories, just the way search engines
track down information on the internet," said Weizhen (Zane) Xie,
Ph.D., a cognitive psychologist and post-doctoral fellow at the NIH's
National Institute of Neurological Disorders and Stroke (NINDS), who
led the study published in Nature Human Behaviour. "We hope that these
results can be used as a roadmap to evaluate the health of a person's
memory and brain." Dr. Xie and his colleagues first spotted these words
when they re-analyzed the results of memory tests taken by 30 epilepsy
patients who were part of a clinical trial led by Kareem Zaghloul, M.D.,
Ph.D., a neurosurgeon and senior investigator at NINDS. Dr. Zaghloul's
team tries to help patients whose seizures cannot be controlled by drugs, otherwise known as intractable epilepsy. During the observation period, patients spend several days at the NIH's Clinical Center with surgically implanted electrodes designed to detect changes in brain activity.

"Our goal is to find and eliminate the source of these harmful and
debilitating seizures," said Dr. Zaghloul. "The monitoring period also
provides a rare opportunity to record the neural activity that controls
other parts of our lives. With the help of these patient volunteers we
have been able to uncover some of the blueprints behind our memories."
The memory tests were originally designed to assess episodic memories,
or the associations -- the who, what, where and how details -- we make
with our past experiences. Alzheimer's disease and other forms of dementia often destroys the brain's capacity to make these memories.

Patients were shown pairs of words, such as "hand" and "apple," from
a list of 300 common nouns. A few seconds later they were shown one
of the words, for instance "hand," and asked to remember its pair,
"apple." Dr. Zaghloul's team had used these tests to study how neural
circuits in the brain store and replay memories.



==========================================================================
When Dr. Xie and his colleagues re-examined the test results, they found
that patients successfully recalled some words more often than others, regardless of the way the words were paired. In fact, of the 300 words
used, the top five were on average about seven times more likely to be successfully recalled than the bottom five.

At first, Dr. Zaghloul and the team were surprised by the results
and even a bit skeptical. For many years scientists have thought that successful recall of a paired word meant that a person's brain made
a strong connection between the two words during learning and that
a similar process may explain why some experiences are more memorable
than others. Also, it was hard to explain why words like "tank," "doll,"
and "pond" were remembered more often than frequently used words like
"street," "couch," and "cloud." But any doubts were quickly diminished
when the team saw very similar results after 2,623 healthy volunteers
took an online version of the word pair test that the team posted on
the crowdsourcing website Amazon Mechanical Turk.

"We saw that some things -- in this case, words -- may be inherently
easier for our brains to recall than others," said Dr. Zaghloul. "These
results also provide the strongest evidence to date that what we
discovered about how the brain controls memory in this set of patients
may also be true for people outside of the study." Dr. Xie got the idea
for the study at a Christmas party which he attended shortly after his
arrival at NIH about two years ago. After spending many years studying how
our mental states -- our moods, our sleeping habits, and our familiarity
with something -- can change our memories, Dr. Xie joined Dr.

Zaghloul's team to learn more about the inner-workings of the brain.



==========================================================================
"Our memories play a fundamental role in who we are and how our brains
work.

However, one of the biggest challenges of studying memory is that people
often remember the same things in different ways, making it difficult
for researchers to compare people's performances on memory tests," said
Dr. Xie. "For over a century, researchers have called for a unified
accounting of this variability.

If we can predict what people should remember in advance and understand
how our brains do this, then we might be able to develop better ways
to evaluate someone's overall brain health." At the party, he met
Wilma Bainbridge, Ph.D., an assistant professor in the department of
psychology at the University of Chicago, who, at the time was working as
a post-doctoral fellow at the NIH's National Institute of Mental Health
(NIMH). She was trying to tackle this same issue by studying whether
some things we see are more memorable than others.

For example, in one set of studies of more than 1000 healthy volunteers,
Dr.

Bainbridge and her colleagues found that some faces are more memorable
than others. In these experiments, each volunteer was shown a steady
stream of faces and asked to indicate when they recognized one from
earlier in the stream.

"Our exciting finding is that there are some images of people or places
that are inherently memorable for all people, even though we have each
seen different things in our lives," said Dr. Bainbridge. "And if image memorability is so powerful, this means we can know in advance what
people are likely to remember or forget." Nevertheless, these results
were limited to understanding how our brains work when we recognize
something we see. At the party, Drs. Xie and Bainbridge wondered whether
this idea could be applied to the recall of memories that Dr.

Zaghloul's team had been studying and if so, what would that tell us
about how the brain remembers our past experiences? In this paper,
Dr. Xie proposed that the principles from an established theory, known
as the Search for Associative Memory (SAM) model, may help explain their initial findings with the epilepsy patients and the healthy controls.

"We thought one way to understand the results of the word pair tests was
to apply network theories for how the brain remembers past experiences. In
this case, memories of the words we used look like internet or airport
terminal maps, with the more memorable words appearing as big, highly trafficked spots connected to smaller spots representing the less
memorable words," said Dr.

Xie. "The key to fully understanding this was to figure out what connects
the words." To address this, the researchers wrote a novel computer
modeling program that tested whether certain rules for defining how
words are connected can predict the memorability results they saw in
the study. The rules were based on language studies which had scanned
thousands of sentences from books, news articles, and Wikipedia pages.

Initially, they found that seemingly straightforward ideas for connecting
words could not explain their results. For instance, the more memorable
words did not simply appear more often in sentences than the less
memorable ones. Similarly, they could not find a link between the relative "concreteness" of a word's definition and its memorability. A word like
"moth" was no more memorable than a word that has more abstract meanings,
like "chief." Instead, their results suggested that the more memorable
words were more semantically similar, or more often linked to the meanings
of other words used in the English language. This meant, that when the researchers plugged semantic similarity data into the computer model
it correctly guessed which words that were memorable from patients and
healthy volunteer test. In contrast, this did not happen when they used
data on word frequency or concreteness.

Further results supported the idea that the more memorable words
represented high trafficked hubs in the brain's memory networks. The
epilepsy patients correctly recalled the memorable words faster than
others. Meanwhile, electrical recordings of the patients' anterior
temporal lobe, a language center, showed that their brains replayed the
neural signatures behind those words earlier than the less memorable
ones. The researchers saw this trend when they looked at both averages
of all results and individual trials, which strongly suggested that the
more memorable words are easier for the brain to find.

Moreover, both the patients and the healthy volunteers mistakenly
called out the more memorable words more frequently than any other
words. Overall, these results supported previous studies which suggested
that the brain may visit or pass through these highly connected memories,
like the way animals forage for food or a computer searches the internet.

"You know when you type words into a search engine, and it shows you
a list of highly relevant guesses? It feels like the search engine is
reading your mind.

Well, our results suggest that the brains of the subjects in this study
did something similar when they tried to recall a paired word, and we
think that this may happen when we remember many of our past experiences,"
said Dr. Xie.

"Our results also suggest that the structure of the English language
is stored in everyone's brains and we hope that, one day, it is used to overcome the variability doctors face when trying to evaluate the health
of a person's memory and brain." The team is currently exploring ways
to incorporate their results and computer model into the development of
memory tests for Alzheimer's disease and other forms of dementia.


========================================================================== Story Source: Materials provided by NIH/National_Institute_of_Neurological_Disorders_and Stroke. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Weizhen Xie, Wilma A. Bainbridge, Sara K. Inati, Chris I. Baker,
Kareem
A. Zaghloul. Memorability of words in arbitrary verbal associations
modulates memory retrieval in the anterior temporal lobe. Nature
Human Behaviour, 2020; DOI: 10.1038/s41562-020-0901-2 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200629120204.htm

--- up 22 weeks, 6 days, 2 hours, 38 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)