BBC News Online / Sci-Tech
June 2, 1999
A computer made of neurons taken from leeches has been
created by US scientists.
"At the moment, the device can perform simple sums - the
team calls the novel calculator the "leech-ulator".
But their aim is to devise a new generation of fast and
flexible computers that can work out for themselves how to
solve a problem, rather than having to be told exactly what
Professor Bill Ditto, at the Georgia Institute of
Technology, is leading the project and says he is amazed
that today's computers are still so dumb.
"Ordinary computers need absolutely correct information
every time to come to the right answer," he says. "We hope a
biological computer will come to the correct answer based on
partial information, by filling in the gaps itself."
The device the team has built can "think for itself" because
the leech neurons are able to form their own connections
from one to another. Normal silicon computers only make the
connections they are told to by the programmer.
This flexibility means the biological computer works out it
own way of solving the problem. "With the neurons, we only
have to direct them towards the answer and they get it
themselves," says Professor Ditto.
This approach to computing is particularly suited to pattern
recognition tasks like reading handwriting, which would take
enormous amounts of power to do well on a conventional
The neurons are harnessed in a petri dish by inserting
micro-electrodes into them. Each neuron has its own
electrical activity and responds in its own way to an
These features can be used to make each neuron represent a
number. Calculations are then performed by linking up the
Leech neurons are used because they have been extensively
studied and are well understood.
Though much simpler, the neuron computer works in a similar
way to the human brain. Professor Ditto says a robot brain
is his long-term aim, noting that conventional
supercomputers are far too big for a robot to carry around.
"We want to be able to integrate robotics, electronics and
these type of computers so that we can create more sentient
robots," he says.
However, in the immediate future, the team from Georgia Tech
and Emory University are working on enabling their computer
to do multiplication.
The biological computer is featured on BBC One's Tomorrow's
World at 1930 BST on Wednesday 2 June 1999.
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