Nervy chip may open window into brain.

In a feat that blurs the lines between science fiction and reality, researchers in Germany have combined living brain cells and semiconductor electronics in a single circuit.

The new microdevice, which uses snail neurons because they are conveniently large, represents a step toward more-complex hybrid circuits, says Peter Fromherz, leader of the work. Such circuits would include up to hundreds of neurons and may enable neuroscientists to directly probe the physiological processes of memory and learning, he says.

"We want to make a biological neural network ... and then supervise it, record [from] it, and look at what's going on," says Fromherz.

Finding ways of directly linking semiconductor components and cells also may further medical and technological applications, he notes. Teams in other labs are trying to meld brain tissue with microchips to make implants that can restore sight and computers that exploit nerve cells' information-processing abilities.

But those teams connect cells to circuits by impaling the cells with needle-like electrodes, Fromherz notes. That's how scientists recently commandeered a slice of a lamprey's brain to control a light-sensitive robot (SN: 11/11/00, p. 309).

Fromherz and Gunther Zeck, both of the Max Planck Institute for Biochemistry in Munich, describe their snail-neuron-based circuit in the Aug. 28 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES.

To make their circuit, the duo patterned transistors onto a silicon wafer, placed snail neurons onto the surface, and then immersed the device in a cell-sustaining broth. The team also has begun experimenting with rat neurons. While those cells are smaller and harder to work with, they're more like human neurons than snail neurons are.