NeuroTalk Support Groups - "Bionic" solution for nerve damage?

This is an article from "The Economist", Feb. 24, 2007. Since none of us are making money off of this, I'm sharing the entire article without (I think) violating the copywrite.

Quote:

Smart prosthetics

Bionic people
Feb 22nd 2007 | SAN FRANCISCO
From The Economist print edition

We can rebuild him. We have the technology

ABLE-BODIED readers, imagining themselves crippled by a broken spine, might not necessarily think of urinary incontinence as being at the top of the list of their problems. Ask those who are actually crippled, though, and it is, indeed, top for all those who do not need mechanical help to breathe. Designing electronic bladder-control devices is therefore not the minor sideline that might naively be thought. And that is exactly what William de Groat of the University of Pittsburgh does.

Dr de Groat was one of a group of speakers at this week's meeting of the American Association for the Advancement of Science who described recent advances in what they refer to as smart prosthetics—and the rest of the world, in thrall to a 1970s television series called “The Six Million Dollar Man”, refers to as bionics. What these researchers are actually engaged in, though, is the construction of parallel nervous systems that fill in what injury or disease has destroyed.

A healthy individual's bladder is regulated by his brain. One set of nerves keeps it relaxed while another keeps tight the sphincter through which it empties. When stretch receptors in the bladder's wall tell the brain it is full, the system goes into reverse. (How much control an individual has over this depends on the signal from the stretch receptors.)

If the spinal cord is damaged in a way that cuts the bladder off from the brain, the nervous tissue below the break will often remodel itself to create a new bladder-emptying reflex. But it does not do a very good job. The bladder neither fills nor empties properly. Dr de Groat's device overcomes this by stimulating one particular nerve that is connected to the sphincter. Studies in animals have shown that signals from this nerve can control the new bladder reflex. Low-frequency electrical stimulation prompts urine storage. High-frequency stimulation prompts emptying. Although the device will not restore voluntary voiding, and patients will not know when they are going to urinate, the bladder will empty more completely and far less frequently than without the prosthesis. This not only reduces incontinence, but also the risk of bladder infection.

Having solved the problem of urination, however, most of those paralysed by spinal-cord injury would like to be able to move again. Hunter Peckham of Case Western Reserve University in Cleveland, Ohio, and John Donoghue of Brown University in Rhode Island are trying to help them to do just that.

Dr Peckham's parallel nervous system picks up electrical signals from the neck and shoulder muscles. These muscles have some involvement in normal arm and leg movement, as the body's whole posture changes when the limbs move. When they twitch useful information about the brain's intentions can be extracted from them.

A cable that runs under the skin from the neck electrodes to the patient's abdomen carries information to a small box that transmits it to another box, which is worn over the skin and contains a computer processor. The two boxes form the alternative nervous system's alternative brain. A program written by Dr Peckham's colleagues interprets the signal and decides which arm or leg muscles need to contract, and by how much, in order to accomplish what the brain is trying to achieve. Each of the relevant muscles has been wired up to the internal box (which is powered by electrical induction from a battery in the external one). The information on how much to contract is translated into pulses of electricity that are sent to each of the relevant muscles and bingo! a previously paralysed patient is able to pick things up, stand or even walk—albeit with the assistance of a Zimmer frame (a walker without wheels, see: http://en.wikipedia.org/wiki/Zimmer_Frame Wings42).

Dr Donoghue's system goes even further. He has been experimenting with the idea of collecting signals straight from the brain's motor cortex and using them to direct mechanical devices such as artificial arms and even wheelchairs. After extensive trials on monkeys, he has now studied four human patients who each have had an array of 100 tiny electrodes implanted in their brains. These people are able to manipulate objects using mechanical arms and hands.

The next step would be to link the two ideas together and have Dr Donoghue's brain electrodes direct Dr Peckham's boxes. That really would act like an artificial nervous system bypassing the patient's broken natural one. And it shouldn't cost $6m a man.