brain prosthesis/implant news

Allen L. Barker alb at datafilter.com
Sun Jun 20 23:27:05 EST 2004

World's first brain prosthesis revealed
19:00 12 March 03
Duncan Graham-Rowe

The world's first brain prosthesis - an artificial hippocampus - is
about to be tested in California. Unlike devices like cochlear
implants, which merely stimulate brain activity, this silicon chip
implant will perform the same processes as the damaged part of the
brain it is replacing.

The prosthesis will first be tested on tissue from rats' brains, and
then on live animals. If all goes well, it will then be tested as a
way to help people who have suffered brain damage due to stroke,
epilepsy or Alzheimer's disease.

Any device that mimics the brain clearly raises ethical issues. The
brain not only affects memory, but your mood, awareness and
consciousness - parts of your fundamental identity, says ethicist Joel
Anderson at Washington University in St Louis, Missouri.

The researchers developing the brain prosthesis see it as a test
case. "If you can't do it with the hippocampus you can't do it with
anything," says team leader Theodore Berger of the University of
Southern California in Los Angeles. The hippocampus is the most
ordered and structured part of the brain, and one of the most
studied. Importantly, it is also relatively easy to test its function.

The job of the hippocampus appears to be to "encode" experiences so
they can be stored as long-term memories elsewhere in the brain. "If
you lose your hippocampus you only lose the ability to store new
memories," says Berger. That offers a relatively simple and safe way
to test the device: if someone with the prosthesis regains the ability
to store new memories, then it's safe to assume it works.

Model, build, interface

The inventors of the prosthesis had to overcome three major
hurdles. They had to devise a mathematical model of how the
hippocampus performs under all possible conditions, build that model
into a silicon chip, and then interface the chip with the brain.

No one understands how the hippocampus encodes information. So the
team simply copied its behaviour. Slices of rat hippocampus were
stimulated with electrical signals, millions of times over, until they
could be sure which electrical input produces a corresponding
output. Putting the information from various slices together gave the
team a mathematical model of the entire hippocampus.

They then programmed the model onto a chip, which in a human patient
would sit on the skull rather than inside the brain. It communicates
with the brain through two arrays of electrodes, placed on either side
of the damaged area. One records the electrical activity coming in
from the rest of the brain, while the other sends appropriate
electrical instructions back out to the brain.

The hippocampus can be thought of as a series of similar neural
circuits that work in parallel, says Berger, so it should be possible
to bypass the damaged region entirely (see graphic).

Memory tasks

Berger and his team have taken nearly 10 years to develop the
chip. They are about to test it on slices of rat brain kept alive in
cerebrospinal fluid, they will tell a neural engineering conference in
Capri, Italy, next week.

"It's a very important step because it's the first time we have put
all the pieces together," he says. The work was funded by the US
National Science Foundation, Office of Naval Research and Defense
Advanced Research Projects Agency.

If it works, the team will test the prosthesis in live rats within six
months, and then in monkeys trained to carry out memory tasks. The
researchers will stop part of the monkey's hippocampus working and
bypass it with the chip. "The real proof will be if the animal's
behaviour changes or is maintained," says Sam Deadwyler of Wake Forest
University in Winston-Salem, North Carolina, who will conduct the
animal trials.

The hippocampus has a similar structure in most mammals, says
Deadwyler, so little will have to be changed to adapt the technology
for people. But before human trials begin, the team will have to prove
unequivocally that the prosthesis is safe.

Collateral damage

One drawback is that it will inevitably bypass some healthy brain
tissue. But this should not affect the patient's memories, says
Berger. "It would be no different from removing brain tumours," where
there is always some collateral damage, says Bernard Williams, a
philosopher at Britain's University of Oxford, who is an expert in
personal identity.

Anderson points out that it will take time for people to accept the
technology. "Initially people thought heart transplants were an
abomination because they assumed that having the heart you were born
with was an important part of who you are."

While trials on monkeys will tell us a lot about the prosthesis's
performance, there are some questions that will not be answered. For
example, it is unclear whether we have any control over what we
remember. If we do, would brain implants of the future force some
people to remember things they would rather forget?

The ethical consequences of that would be serious. "Forgetting is the
most beneficial process we possess," Williams says. It enables us to
deal with painful situations without actually reliving them.

Another ethical conundrum concerns consent to being given the
prosthesis, says Anderson. The people most in need of it will be those
with a damaged hippocampus and a reduced ability to form new
memories. "If someone can't form new memories, then to what extent can
they give consent to have this implant?"


Human subjects play mind games
'Look, Ma, No hands'
That's using your brain.
Contact: Tony Fitzpatrick
tony_fitzpatrick at wustl.edu
Washington University in St. Louis

For the first time in humans, a team headed by researchers at
Washington University in St. Louis has placed an electronic grid atop
patients' brains to gather motor signals that enable patients to play
a computer game using only the signals from their brains.

The use of a grid atop the brain to record brain surface signals is a
brain-machine interface technique that uses electrocorticographic
(ECoG) activity -- data taken invasively right from the brain
surface. It is an alternative to the status quo, used frequently
studying humans, called electroencephalographic activity (EEG) -- data
taken non-invasively by electrodes outside the brain on the skull.

The breakthrough is a step toward building biomedical devices that can
control artificial limbs, some day, for instance, enabling the
disabled to move a prosthetic arm or leg by thinking about it. The
study was published in the June 8, 2004 issue of the Journal of Neural
Engineering and was partially funded by the National Institutes of
Health (NIH).

Eric C. Leuthardt, M.D., a physician in the Department of Neurological
Surgery, Barnes Jewish Hospital, and Daniel Moran, Ph.D., assistant
professor of biomedical engineering, performed their research on four
adult epilepsy patients who had the grids implanted so that
neurologists can find the area in the brain serving as the focus for
an epileptic seizure, with hopes of removing it to avoid future
seizures. To do this, the patients and their doctors must wait for a

With approval of the patients and the Washington University School of
Medicine Institutional Review Board, Leuthardt and Moran connected the
patients to a sophisticated computer running a special program known
as BCI2000 (developed by their collaborators at the Wadsworth Center)
which involves a video game that is linked to the ECoG grid. They then
asked the patients to do various motor and speech tasks, moving their
hands various ways, talking, and imagining. The team could see from
the data which parts of the brain correlate to these movements. They
then asked the patients to play a simple, one-dimensional computer
game involving moving a cursor up or down towards one of two
targets. They were asked to imagine various movements or imagine
saying the word "move," but not to actually perform them with their
hands or speak any words by mouth. When they saw the cursor in the
video game, they then controlled it with their brains.

"We closed the loop," said Moran. "After a brief training session, the
patients could play the game by using signals that come off the
surface of the brain. They achieved between 74 and 100 percent
accuracy, with one patient hitting 33 out of 33 targets correctly in a

The ECoG method is orders of magnitude faster to learn than EEG.

"It takes many months to train using EEG, whereas our approach was
done basically in an hour or so," Moran said. "That's because we got
the signals from the surface of the brain rather than having to go
through the skull."

"To put this in perspective," Leuthardt said, " the previous EEG based
systems are equivalent to a 1908 Wright brothers airplane in regards
to speed of learning to achieve control. Right now with our results
we're flying around in an F-16 jet."

The two note that ECoG has higher spatial resolution, broader
bandwidth and higher amplitude than the EEG approach, allowing the use
of more electrodes and the gain of higher frequencies, which let the
researchers go another step -- they tried it out on a 2-D game and
were able to predict where the patients would move by seeing which
electrodes were active on the grid. However, this group of patients
did not control movement in the 2-D game with their brains, as they
had with the 1-D game.

The researchers next want to try patients out with 2-D games to see if
they can control the movements with their brains. They also will
implant the ECoG grids into non-human primates -- monkeys -- to see
how long they can get reliable data from them, the goal being
eventually to develop a brain-machine interface device that will last
years, say, up to 10, making the choice to have one implanted into a
motor-impaired patient's brain practical.

"We are pretty confident that we can get signals from these for many
years," Moran said. "There will have to be a rigorous study on monkeys
for an indeterminate number of years before we can consider permanent
implants in human subjects, but we're really excited about this
advance. Brain-computer interface research is one of the hottest
things going in biomedical engineering today."

"Our work," said Leuthardt, "has significant clinical relevance to
potentially improve the lives of people with such disabilities as ALS
and spinal cord injuries. Additionally, this type of research is
producing some fundamental insights into a myriad of different fields
ranging from neurophysiology to clinical medicine."


Collaborators on the study are Gerwin Schalk and Jonathan R. Wolpaw,
M.D., of the Wadsworth Center, New York State Department of Health,
Albany, N.Y., and Jeffrey G. Ojemann, M.D., University of Washington
School of Medicine.

Mind Control: TT&P ==> http://www.datafilter.com/mc
Home page: http://www.datafilter.com/alb
Allen Barker

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