- "It has a touch of science fiction," admit
the scientists who have wired up the first conducting nerve chip. The electronic
circuit, grown from silicon and nerve cells, brings brain-repair chips,
advanced biosensors and biological computers a small step towards reality.
-
- 'Neuroelectronics' combines nerve cells and microchips.
It could one day lead to 'neuroprosthetic' implants replacing damaged nervous
tissue, and advanced computers mimicking living, learning circuits.
-
- Peter Fromherz and Gunther Zeck of the Max Planck Institute
for Biochemistry in Munich placed snail nerve cells on a silicon chip,
fencing them in place with microscopic plastic pegs. Neighbouring cells
grew connections with each other and with the chip1.
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- A stimulator beneath each nerve cell created a change
in voltage that triggered an electrical impulse to travel through the cell.
Electrical pulses applied to the chip passed from one nerve cell to another,
and back to the chip to trip a silicon switch. The circuit literally went
live.
-
- Designing circuits by fencing in cells is "cute",
says Eve Marder, who studies neural networks at Brandeis University in
Waltham, Massachusetts. She says that by letting us create nerve-based
circuits at will, the technique "is a lovely way" to probe the
workings of the nervous system, for example to investigate how memories
are formed.
-
- The main obstacle to neuroelectronics is the difficulty
of reliably connecting devices and living tissue, Marder explains. In previous
attempts to build such circuits, the nerve cells moved when they grew connections
- by caging the cells in, Fromherz and Zeck got round this problem. Using
silicon means electronic devices can be built into a standard chip.
-
- Biosensors for testing toxic or pharmaceutical substances
on nerve cells and neuroprosthetics are among the ambitious applications
for such chips. For example, chips could bridge a damaged section of the
spinal cord.
-
- But such projects are still the realms of science fiction,
as are "neurocomputers with living neurons or brains", says Fromherz.
Meanwhile nerve networks will hopefully teach scientists how to mimic the
brain's properties.
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-
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- References
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- 1. Zeck, G. & Fromherz, P.Noninvasive neuroelectronic
interfacing with synaptically connected snail neurons on a semiconductor
chip. Proceedings of the National Academy of Sciences, 98, 10457 - 10462,
(2001).
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- © Nature News Service / Macmillan Magazines Ltd
2001
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