- Two men 'locked in' to their bodies by
complete paralysis have been able to think messages to the outside world.
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- A team from the University of Tubingen,
Germany, report in Nature today that people with the progressive neurological
disease amyotrophic lateral sclerosis (ALS) have been able to spell out
sentences on a screen by the power of thought alone. ALS, or motor neurone
disease, is a progressive wasting disease that can ultimately leave the
sufferer unable to move any muscle voluntarily.
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- Stephen Hawking of Cambridge is the world's
most famous case. Professor Hawking was left with very slight finger movement,
enough to manipulate a computer pad and keep on with his research into
the history of the universe.
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- Two patients at the institute of medical
psychology and behavioural neurobiology at Tubingen were left with very
weak eye movement. Although the body becomes helpless, the brain and consciousness
remain intact.
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- The late French writer Jean-Dominique
Bauby dictated a book called The Diving Bell and the Butterfly using only
eye movement, and described the experience of locked-in syndrome as if
'something like a giant invisible diving bell holds my whole body prisoner.'
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- For almost a decade, teams of scientists
around the world have been trying to harness computer technology to open
the diving bell.
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- The two men in Tubingen originally 'talked'
to Niels Birbaumer and his colleagues by moving their eyes to conduct a
yes/no dialogue. They found it exhausting. Although they could not move
any other muscles, they still 'fired' electrical processes in their brains
as they thought.
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- Different thoughts trigger tiny bursts
of electricity in different parts of the brain, and newly developed scanners
can now 'read' this activity in separate places. The discovery opened several
possibilities but the most urgent was communication with the otherwise
helpless.
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- A team at Imperial College, London, proposed
using the technology to 'ask' people in deep comas whether they were aware
of their world. Others hope to harness it to literally open doors or switch
on computers for wheelchair-bound workers. But the Tubingen team used it
to stay in touch with two people in stages of paralysis so advanced that,
for the past four years their air and nourishment has been supplied artificially.
They were fitted with electroencephalogram (EEG) devices that could drive
electronic spelling devices.
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- Using the EEG hook-up, they could push
a cursor on a video screen to select letters of the alphabet. Such techniques
have been used before often with healthy volunteers but this is the first
time it has worked with people who needed it most.
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- The patients were trained to produce
voluntary changes in their own brainwave states called slow cortical potentials,
or SCPs, lasting two to four seconds. The training itself was slow, taking
six to 12 sessions of five minutes each day, while they tried to move a
ball nearer or away from a box on the screen.
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- Dr Birbaumer and his team discovered
it could be done, and quite accurately. Once the two patients were getting
things correct 75 per cent of the time, the scientists presented them with
sets of letters on a screen.
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- If the subject's brain activity gave
a 'yes' signal, the group of letters was split, and then split again until
only one letter was left - a letter which began to spell a word, and then
a sentence.
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- 'Our data indicate that patients who
lack muscular control can learn to control variations in their SCPs sufficiently
accurately to operate an electronic spelling device,' they report. The
process is slow one of the patients composed a letter to Dr Birbaumer at
the rate of two characters a minute, but it is reliable and precise.
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- 'One of our patients did an interview
with a journalist in Switzerland. He told her he is very glad about the
system. He is independent now, he can write letters,' said Andrea Kubler,
one of the Tubingen researchers, yesterday. 'Both patients told us it is
not exhausting. One told us it was much more exhausting to talk with his
eyeball movements.'
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- The discovery offers hope, but not yet
for everybody. Stephen Roberts of Imperial College, who has plans for a
clinical trial this year, said the problem is that not all subjects are
good at controlling the cursor on the screen. 'For people for whom it works,
they report they really feel as if they are in control of the cursor for
others this never seems to happen, so it is still not perfect.
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- 'All these methods have got a very long
way to go yet, but work such as at Tubingen is really vital as it shows
that at least some locked-in patients can use an EEG-based system, which
is wonderful.'
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