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'Mind-reading' experiment highlights how
brain records memories
It may be possible to "read" a person's
memories just by looking at brain activity,
according to research carried out by
Wellcome Trust scientists.
In a study published today in the journal
Current Biology , they show that our
memories are recorded in regular patterns, a
finding which challenges current scientific
thinking.
Demis Hassabis and Professor Eleanor Maguire
at the Wellcome Trust Centre for
Neuroimaging at UCL (University College
London) have previously studied the role of
a small area of the brain known as the
hippocampus which is crucial for navigation,
memory recall and imagining future events.
Now, the researchers have shown how the
hippocampus records memory.
When we move around, nerve cells (neurons)
known as "place cells", which are located in
the hippocampus, activate to tell us where
we are.
Hassabis, Maguire and colleagues used an
fMRI scanner, which measures changes in
blood flow within the brain, to examine the
activity of these places cells as a
volunteer navigated around a virtual reality
environment.
The data were then analysed by a computer
algorithm developed by Demis Hassabis.
"We asked whether we could see any
interesting patterns in the neural activity
that could tell us what the participants
were thinking, or in this case where they
were," explains Professor Maguire, a
Wellcome Trust Senior Research Fellow.
"Surprisingly,
just by looking at the brain data we could
predict exactly where they were in the
virtual reality environment. In other words,
we could 'read' their spatial memories."
Earlier studies in rats have shown that
spatial memories – how we remember where we
are – are recorded in the hippocampus.
However, these animal studies, which
measured activity at the level of individual
or dozens of neurons at most, implied that
there was no structure to the way that these
memories are recorded.
Hassabis
and Maguire's work appears to overturn this
school of thought.
"fMRI scanners enable us to see the bigger
picture of what is happening in people's
brains," she says.
" By looking at activity over tens of
thousands of neurons, we can see that there
must be a functional structure – a pattern –
to how these memories are encoded.
Otherwise, our experiment simply would not
have been possible to do."
Professor Maguire believes that this
research opens up a range of possibilities
of seeing how actual memories are encoded
across the neurons, looking beyond spatial
memories to more enriched memories of the
past or visualisations of the future.
"Understanding how we as humans record our
memories is critical to helping us learn how
information is processed in the hippocampus
and how our memories are eroded by diseases
such as Alzheimer's," added Demis Hassabis.
"It's also a small step towards the idea of
mind reading, because just by looking at
neural activity, we are able to say what
someone is thinking."
Professor Maguire led a study a number of
years ago which examined the brains of
London taxi drivers, who spend years
learning "The Knowledge" (the maze of London
streets).
She showed that in these cabbies, an area to
the rear of the hippocampus was enlarged,
suggesting that this was the area involved
in learning location and direction.
In the new study, Hassabis, Maguire and
colleagues found that the patterns relating
to spatial memory were located in this same
area, suggesting that the rear of the
hippocampus plays a key role in representing
the layout of spatial environments.
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