- It sounds like the stuff of science fiction: a brain
nurtured in a Petri dish learns to pilot a fighter plane as scientists
develop a new breed of "living" computer. In ground-breaking
experiments in a Florida laboratory, however, that is exactly what is happening.
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- The "brain", grown from 25,000 neural cells
extracted from a single rat embryo, has been taught to fly an F-22 jet
simulator by scientists at the University of Florida.
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- They hope that the remarkable research into neural computation
will help them develop sophisticated hybrid computers, with a thinking
biological component.
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- One target is to install living computers in unmanned
aircraft so that they can be deployed on missions that are too dangerous
for humans because of the risk of attack or hazardous terrain. They could
also be used in remote bomb-clearance machines. Separately, it is hoped
that the research will provide the basis for developing new drugs to treat
brain diseases such as epilepsy, by investigating what happens when cells
stop working together normally.
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- The brain-in-a-dish is the idea of Thomas DeMarse, a
37-year-old assistant professor of biomedical engineering at the University
of Florida. His pioneering work has been praised as a significant insight
into one of the universe's most complex devices - the brain - by leading
American academics and scientific journals.
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- The 25,000 neurons were immersed in a specialised liquid
suspension to keep them alive and then laid across a grid of 60 electrodes
in a small glass dish, measuring only about an inch across.
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- Under the microscope they looked at first like thousands
of grains of sand, but soon the cells begin to connect to form what scientists
are calling a "live computation device" (in effect, a brain).
The electrodes measure and stimulate neural activity in the network, allowing
researchers to study how the brain processes, transforms and stores information.
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- In the most striking experiment, the brain was linked
up to the jet simulator. Manipulated via the electrodes and a desktop computer,
it was taught to control the flight path, even in mock hurricane-strength
winds.
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- "When we first hooked them up, the plane 'crashed'
all the time," said Dr DeMarse. "But over time, the neural network
slowly adapts as the brain learns to control the pitch and roll of the
aircraft. After a while, it produces a nice straight and level trajectory.
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- "The network receives the information about the
aircraft's pitch and roll in the form of stimulation pulses and its responses
change over time. We are its external teachers as it learns."
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- Previously, scientists have been able to monitor the
activity of only a few neurons at a time, but Dr DeMarse and his colleagues
can study in laboratory conditions how thousands of cells conduct calculations
together. It is still a long way from a human brain, which contains about
10 billion neurons.
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- "The goal is to study how cortical networks perform
their neural computations. In these experiments we are using living neurons
to perform the computation required to fly an aircraft. The implications
are extremely important," said Dr DeMarse.
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- The first result could be to enable scientists to build
living elements into traditional computers, enabling more flexible and
varied means of solving problems. Although computers today are extremely
powerful, they still lack the flexibility in working things out that humans
take for granted.
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- Computers, for example, find it difficult to spot the
difference between items such as a table and a lamp if they are unfamiliar
with them. More importantly, they will sometimes fail to recognise the
same table if viewed from different angles, an ability possessed by the
simplest animals.
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- "The algorythms that living computers use are also
extremely fault-tolerant," said Dr DeMarse. "A few neurons die
off every day in humans without any noticeable drop in performance, and
yet if the same were to happen in a traditional silicon-based computer
the results would be catastrophic."
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- These studies and the technologies use to investigate
neural function are important for the understanding of neural computing
but also for investigating when that computation goes awry.
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- "For example, with neural disorders such as epilepsy
we can study how neural activity evolves from a normal to a diseased state,"
he said. "Understanding these processes is important not only for
basic science, but can lead us down new avenues toward better medical treatments."
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- The work by Dr DeMarse and his team is attracting interest
from scientists around the world. The US National Science Foundation has
awarded them a $500,000 grant to produce a mathematical model of how the
neurons compute, and the US National Institute of Health is funding research
into epilepsy.
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- http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2004/12/05/wbrain
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