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Nanowire Arrays Can Detect Signals Along Individual Neurons


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http://www.news.harvard.edu/gazette/2006/0...9-nanowire.html

 

Nanowire arrays can detect signals along individual neurons

Merger of nanowires and neurons could boost efforts to measure and understand brain activity

 

By Steve Bradt

 

FAS Communications

 

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 group has previously shown that nanowires can detect, with great precision, molecular markers indicating the presence of cancer in the body, as well as single viruses. The group's latest work takes advantage of the size similarities between ultra-fine silicon nanowires and the axons and dendrites projecting from nerve cells: Nanowires, like neuronal offshoots, are just tens of nanometers in width, making the thin filaments a good match for intercepting nerve signals.

 

Because the nanowires are so slight -- their contact with a neuron is no more than 20 millionths of a meter in length -- Lieber and colleagues were able to measure and manipulate electrical conductance at as many as 50 locations along a single axon.

 

The current work involves measurement of signals only within single mammalian neurons; the researchers are now working toward monitoring signaling among larger networks of nerve cells. Lieber says the devices could also eventually be configured to measure or detect neurotransmitters, the chemicals that leap synapses to carry electrical impulses from one neuron to another.

 

"This work could have a revolutionary impact on science and technology," Lieber says. "It provides a powerful new approach for neuroscience to study and manipulate signal propagation in neuronal networks ata level unmatched by other techniques; it provides a new paradigm for building sophisticated interfaces between the brain and external neural prosthetics; it represents a new, powerful, and flexible approach for real-time cellular assays useful for drug discovery and other applications; and it opens the possibility for hybrid circuits that couple the strengths of digital nanoelectronic and biological computing components."

 

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.

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We are being taught this right now as if it's been around for a while... I'm in neuropharmacology right now, and I find that amazing. This will help us understand so much more once we can apply the technology to more specific clinical and practical research goals, instead of descriptive science.

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I have a book by Joel Garreau called Radical Evolution, and in the first chapter he talks of a "telekinetic" owl monkey named Belle. DARPA had funded this project, and they've trained her to move a joystick to the left or right in response to a light signal which indicates which direction for her to move it. "Her Duke researchers line up probes thinner than the finest sewing thread right next to individual neurons in different regions of Belle's motor cortex--the part of the brain that plans movements. These are linked to two computers, one in the next room and another 600 miles north, at MIT, via the internet. The computers each control a robotic arm. Then the researchers disconnect her joystick and start Belle's game. Sure enough, not only is she able to play it splendidly using just her thoughts, but the two robotic arms instantly mimic the motions that Belle's arm would make to control the joystick, 'like dancers choreographed by the electrical impulses sparking in Belle's mind,' her researchers report. The first time she did it, the tow labs, in North Carolina and New England, erupted into loud celebration." They're still trying to make the whole thing seamless, but for now (at the time Joel wrote the book; it was published in 2005) it's only a one-way link between a brain and machine...they haven't figured out yet how to get signals to the brain from whatever machine they've hooked you up to. But this has obvious potential...if they get this going both ways, they could strap on new legs (or mechanical muscles) to a paraplegic and wire them directly to the brain. Pretty bitchin' stuff.

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I have a book by Joel Garreau called Radical Evolution, and in the first chapter he talks of a "telekinetic" owl monkey named Belle. DARPA had funded this project, and they've trained her to move a joystick to the left or right in response to a light signal which indicates which direction for her to move it. "Her Duke researchers line up probes thinner than the finest sewing thread right next to individual neurons in different regions of Belle's motor cortex--the part of the brain that plans movements. These are linked to two computers, one in the next room and another 600 miles north, at MIT, via the internet. The computers each control a robotic arm. Then the researchers disconnect her joystick and start Belle's game. Sure enough, not only is she able to play it splendidly using just her thoughts, but the two robotic arms instantly mimic the motions that Belle's arm would make to control the joystick, 'like dancers choreographed by the electrical impulses sparking in Belle's mind,' her researchers report. The first time she did it, the tow labs, in North Carolina and New England, erupted into loud celebration." They're still trying to make the whole thing seamless, but for now (at the time Joel wrote the book; it was published in 2005) it's only a one-way link between a brain and machine...they haven't figured out yet how to get signals to the brain from whatever machine they've hooked you up to. But this has obvious potential...if they get this going both ways, they could strap on new legs (or mechanical muscles) to a paraplegic and wire them directly to the brain. Pretty bitchin' stuff.

 

I like the noninvasive helmet method much better. It'd be the new remote control. Just wear you Thinking Cap™ and control all the appliances in your house with a single thought! :) But yes, with prostheses it's especially promising -- which is a very good thing because the typical leg or arm replacement is much behind the curve and very uncomfortable. It's actully the veterans returning ome from Bush's wars that are pushing the hardest fro the implementation of this technology.

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This is pretty wild stuff. If you extrapolate a bit you could imagine humans interfacing with special limbs that could never have been part of normal evolution of the human specie.

 

Imagine for a moment humans equipped and interfacing directly with an implant emulating the hormone detecting components of insects. How about a pair of artificial wings attached to your back and directly controlled by your brain, I've always dreamt of free flight :HaHa:

 

Humans could equipped to physically experience a variety of enhanced features that are currently only available to other species in the animal world.

 

Wow, yeah, I hadn't thought of that. Yes, this technology where man can directly interface with machine has limitless possibilities!

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What about somehow recording the neural impulses in say, the area of the brain that processes vision and hearing and then being able to replay those recordings, stimulating the brain with the same impulses that were recorded, effectively allowing a person to replay vision and sound of a previous experience.

 

Maybe you could even replay it for someone else.

 

Hell, you could even wire a camera directly into a blind person's brain! Sure beats a bit of dirt and spit rubbed in your eye...

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What about somehow recording the neural impulses in say, the area of the brain that processes vision and hearing and then being able to replay those recordings, stimulating the brain with the same impulses that were recorded, effectively allowing a person to replay vision and sound of a previous experience.

 

Maybe you could even replay it for someone else.

 

Hell, you could even wire a camera directly into a blind person's brain! Sure beats a bit of dirt and spit rubbed in your eye...

 

There have been planety of movies like that. I always thought it was really cool. Strange Days featured this idea prominently.

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