Nanowire arrays can detect signals along individual neurons

Opening a whole new interface between nanotechnology and neuroscience, scientists at Harvard University have used slender silicon nanowires to detect, stimulate, and inhibit nerve signals along the axons and dendrites of live mammalian neurons.

Harvard chemist Charles M. Lieber and colleagues report on this marriage of nanowires and neurons this week in the journal Science.

"We describe the first artificial synapses between nanoelectronic devices and individual mammalian neurons, and also the first linking of a solid-state device -- a nanowire transistor -- to the neuronal projections that interconnect and carry information in the brain," says Lieber, the Mark Hyman Jr. Professor of Chemistry in Harvard's Faculty of Arts and Sciences and Division of Engineering and Applied Sciences. "These extremely local devices can detect, stimulate, and inhibit propagation of neuronal signals with a spatial resolution unmatched by existing techniques."

Electrophysiological measurements of brain activity play an important role in understanding signal propagation through individual neurons and neuronal networks, but existing technologies are relatively crude: Micropipette electrodes poked into cells are invasive and harmful, and microfabricated electrode arrays are too bulky to detect activity at the level of individual axons and dendrites, the neuronal projections responsible for electrical signal propagation and interneuron communication.

By contrast, the tiny nanowire transistors developed by Lieber and colleagues gently touch a neuronal projection to form a hybrid synapse, making them noninvasive, and are thousands of times smaller than the electronics now used to measure brain activity.

Lieber's co-authors on the Science paper are Fernando Patolsky, Brian P. Timko, Guihua Yu, Ying Fang, Andrew B. Greytak, and Gengfeng Zheng, all of Harvard's Department of Chemistry and Chemical Biology. Their work was supported by the Defense Advanced Research Projects Agency and Applied Biosystems.