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From: turbocrazed@webtv.net
Date: Thu Jun 22 2000 - 15:37:23 MDT

Subject: New Chip Mimics Human Brain
>From the AP,
Wednesday June 21 2:02 PM ET
New Chip Mimics Human Brain

AP Photo

Scientists have developed an electronic circuit that mimics the wiring
of the human brain in some ways - an achievement that could
revolutionize computer science and improve understanding of how nature's
most powerful processor works.
The circuit, built on a silicon chip the size of a fingernail, is far
from the thinking machines of science fiction. For one thing, it cannot
learn, the way the brain can.
But researchers say it could result in better speech and object
recognition by computers.
``This is a demonstration of what磗 possible when circuits compute in
biological ways,创 said Rahul Sarpeshkar, a computer science
professor at the Massachusetts Institute of Technology who worked on the
project. ``We磖e still far away from building a brain.创
The findings were published in Thursday's issue of the journal Nature.
The project is the culmination of more than two decades of work using
transistors and silicon to mimic the natural circuitry in the brain. It
is the first time a circuit inspired by the brain's cortex has been
created in hardware.
Traditional circuits work in one of two ways: They are either digital
and specific such as computer processors, or analog and nonspecific like
radio amplifiers. Research suggests the brain is able to do digital and
analog computing at the same time.
Someone watching a highway, for instance, can sort out distinct objects
like a police cruiser, and also perceive changes in direction, speed and
color. Traditional digital circuits in computers are not nearly as
efficient as the brain in perceptual tasks.
The latest research, done at Lucent Technologies' Bell Labs in New
Jersey, combines both digital and analog processing by using artificial
neurons that either excite or inhibit each other based on responses, or
feedback, from other neurons.
``In one simultaneous circuit, both digital selection and analog
amplification can co-exist,创 Sarpeshkar said.
Researchers applied simultaneous electrical currents to two artificial
neurons in their circuit. It selected the stronger of the stimuli and
suppressed its response to the weaker. That is not unlike, say, a frog
choosing which of two flies to eat, the researchers said.
And the circuit, like a brain, maintained its selection as the weaker
current was increased and the stronger decreased.
Another unique aspect of the circuit is that no single element made the
``If you take a Pentium chip and cut a single wire, then it would
probably stop functioning,创 said Richard Hahnloser, another MIT
researcher. ``If you took our circuit, you could cut a wire and it would
still work the same.创
It will be at least 50 years before artificial neural circuitry
approaches the abilities of the brain and its 240 billion neurons,
Sarpeshkar said.
But even simple circuits are useful in demonstrating how biological
networks operate, said Dean Buonomano, a neurobiology professor at the
University of California at Los Angeles.
On the Net: Nature: http://www.nature.com
Bell Labs: http://www.bell-labs.com

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