Computer algorithm created to encode human memories
Last updated: September 29, 2015 5:21 pm
Computer algorithm created to encode human memories
By Clive Cookson, Science Editor
Researchers in the US have developed an implant to help a
disabled brain encode memories, giving new hope to Alzheimer’s sufferers and
wounded soldiers who cannot remember the recent past.
The prosthetic, developed at the University of Southern
California and Wake Forest Baptist Medical Centre in a decade-long
collaboration, includes a small array of electrodes implanted into the brain.
The key to the research is a computer algorithm that
mimics the electrical signalling used by the brain to translate short-term into
permanent memories.
This makes it possible to bypass a damaged or diseased
region, even though there is no way of “reading” a memory — decoding its
content or meaning from its electrical signal.
“It’s like being able to translate from Spanish to French
without being able to understand either language,” said Ted Berger of USC, the
project leader.
The prosthesis has performed well in tests on rats and
monkeys. Now it is being evaluated in human brains, the team told the
international conference of the IEEE Engineering in Medicine and Biology
Society in Milan.
The project is funded by Darpa, the US Defence Advanced
Research Projects Agency, which is interested in new ways to help soldiers
recover from memory loss.
But the researchers say findings could eventually help to
treat neurodegenerative diseases, including Alzheimer’s, by enabling signals to
bypass damaged circuitry in the hippocampus, the brain’s memory centre.
Sensory inputs to the brain — sights, sounds, smells or
feelings — create complex electrical signals, known as spike trains, which
travel through the hippocampus. This neural process involves re-encoding the
signals several times, so they have a quite different electrical signature by
the time they are ready for long-term storage.
Damage that interferes with this translation may prevent
the formation of long-term memories while old ones survive — which is why some
people with brain damage or disease recall events from long ago but not from
the recent past.
The translation algorithm, derived first from animal
experiments, has been extended into humans by studying nine people with
epilepsy who had electrodes implanted in the hippocampus to treat chronic
seizures.
The researchers read the electrical input and output
signals created in the patients’ brains as they conducted simple tasks, such as
remembering the position of different shapes on a computer screen.
These results were used to refine the algorithm until it
could predict with 90 per cent accuracy how the signals would be translated.
“Being able to predict neural signals with the USC model
suggests that it can be used to design a device to support or replace the
function of a damaged part of the brain,” said Robert Hampson of Wake Forest.
The next step will be to send the translated signal back
into the brain of a patient with hippocampal damage, in the hope that this will
bypass the trouble spot and form an accurate long-term memory.
The project at USC and Wake Forest is a vivid example of
the progress being made in neurotechnology by scientists around the world.
Researchers elsewhere are implanting devices that enable
people who are paralysed to carry out simple movements with robotic arms or
even their own limbs. But no one else is using computers to manipulate memory
signals directly in the human brain.
Copyright The Financial Times Limited 2015.
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