[wordup] World's first brain prosthesis revealed

[Adam Shand]

The world is going to be *such* a strange place ...

Adam.

From: http://www.newscientist.com/news/news.jsp?id=ns99993488

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?"

19:00 12 March 03