Why this brain
flies on rat cunning
By
Philip Sherwell
Washington
December 7, 2004
It sounds like science fiction: a brain nurtured in a Petri dish learns to
pilot a fighter plane as scientists develop a new breed of "living"
computer. But in groundbreaking experiments in a Florida laboratory
that is exactly what is happening.
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.
They hope their research into neural computation will help them develop sophisticated
hybrid computers, with a thinking biological component.
One target is to install living computers in unmanned aircraft so they can
be deployed on missions too dangerous for humans. It is also
hoped that the research will provide the basis for developing
new drugs to treat brain diseases such as epilepsy.
The brain-in-a-dish is the idea of Thomas DeMarse, 37, an assistant professor
of biomedical engineering at the University of Florida. His
work has been praised as a significant insight into the brain
by leading US academics and scientific journals.
The 25,000 neurons were suspended in a specialised liquid to keep them alive
and then laid across a grid of 60 electrodes in a small glass
dish.
Under the microscope they looked at first like grains of sand, but soon the
cells begin to connect to form what scientists are calling a
"live computation device" (a brain). The electrodes
measure and stimulate neural activity in the network, allowing
researchers to study how the brain processes, transforms and
stores information.
In the most striking experiment, the brain was linked to the jet simulator.
Manipulated by the electrodes and a desktop computer, it was
taught to control the flight path, even in mock hurricane-strength
winds.
"When we first hooked them up, the plane 'crashed' all the time,"
Dr DeMarse said. "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."
Previously, scientists have been able to monitor the activity of only a few
neurons at a time, but Dr DeMarse and his team can study how
thousands of cells conduct calculations together. But it is
still a long way from a human brain.
"The goal is to study how cortical networks perform their neural computations.
The implications are extremely important," Dr DeMarse said.
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.
Computers, for example, find it difficult to spot the difference between a
table and a lamp if they are unfamiliar with them.
"The algorithms that living computers use are also extremely fault-tolerant,"
Dr DeMarse said. "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."
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 $US500,000 ($A640,000)
grant to produce a mathematical model of how the neurons compute,
and the US National Institute of Health is financing research
into epilepsy.
-Telegraph
http://www.theage.com.au/articles/2004/12/06/1102182227308.html