Neurons switch when stuck on a chip.

A neuron fused to a silicon chip represents a true meeting of the minds--one biological, the other computational. Researchers have fabricated such a hybrid component, a neuron transistor, and are studying its electronic properties.

Martin Jenkner and Peter Fromherz of the Max Planck Institute for Biochemistry in Martinsried, Germany, deposited a single nerve cell from a leech onto a transistor etched into a silicon wafer. After piercing the neuron with a microscopic glass electrode, they stimulated the cell with pulses of current and recorded its behavior.

At first, they recorded via the transistor only a low voltage in response to cell stimulation, but by plunging the electrode deeper into the cell, they triggered a far greater response to the same stimulus. The researchers could switch between these two responses simply by sliding the electrode back and forth about 3 micrometers inside the neuron.

Jenkner and Fromherz report their findings in the Dec. 8, 1997 Physical Review Letters, where they suggest a mechanical explanation. Pushing on the electrode may open ion channels in the neuron's membrane, thus increasing electrical conductance and creating the larger voltage.

However, they need to learn more about the ion channels in leech neurons before they can describe details of any mechanism for the switch.