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 Piloting a wheelchair with the power of the mind

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Date posted: 21/10/2006

Cyberkinetics Neurotechnology Systems, home of the BrainGate neuroprosthetic marvel, have now tested the device in two new patients, one with ALS, a progressive neurodegenerative disease, and the other with brain-stem stroke, a particularly devastating type of stroke that paralyzes the body but leaves the mind intact.

The scientists presented their latest results at the Society for Neurosciences conference this week in Atlanta, GA. At the conference, Donoghue, founder of Cyberkinetics and a neuroscientist at Brown, and Leigh Hochberg, a neurologist at MGH who works with the patients studied, spoke at length about the latest developments in neural prosthetics and their plans for the future.

John Donoghue: The device is the same, but we're using a new filter [a piece of software that decodes neural signals and transmits the command to a user interface, e.g., a computer]. Now it's possible to get quite a good level of control. Patients can move the cursor much more cleanly, and they can point to a target and click on it, just like you would with a mouse.

Leigh Hochberg: The new filter does a much better job of stabilising the cursor. The patients imagine moving their wrist to move the cursor and squeezing their hand to click on a target. Once you have the capacity to move a cursor in two dimensions and point and click, you can imagine a very powerful tool. Patients could control any computer-based device. For example, we could use the same point-and-click concept with a typing board.

We're also working with a company called Rolltalk, which has developed a powerful interface. It was built for people who use eye-based controls [devices that convert directed eye movements into specific commands], but we're adapting it for brain control. One patient has already used it to control the movement of a wheelchair.

John Donoghue: When we first started working with other patients, we weren't sure how similar their responses would be to Matthew's. But we were struck by the similarity. We found that the same types of cells were present, and patients were able to modulate them. All were able to achieve control, with some variability.

Leigh Hochberg: ALS affects motor neurons, but it also affects the motor cortex directly, so there was some question about whether we could use signals from these cells [to control the implant]. However, we saw lots of signals in the motor cortex, and the patient was able to modulate those signals. In fact, he was able to move the cursor immediately, even though he hadn't used those cells in a while.

John Donoghue: This also gives us an unprecedented view into the disease. This is the first opportunity to track neurons in the intact nervous system. Will we be able to see neurons degenerate? It's a whole other potential to this technology.

John Donoghue: We want to make the system automated--right now a technician has to run it. And we want to make the system fully implantable, both to decrease the chance of infection [via the hole in the skull] and to make life more normal for the patient. The system right now is sort of analogous to the first cardiac pacemaker in the 1950s. It had a big cart with an oscilloscope that the patient had to move around.

John Donoghue: We're working on two wireless systems. They both use the same electrode array, but in one case, the array is connected to a titanium can modelled after the cochlear implant.

The can, which is also implanted, contains electronics that can amplify the neural signals and transmit them outside the body. We can then integrate that system with our computer decoder and use the Rolltalk interface to control a wheelchair, lights, or TV.

We have a bench version of the system that works, but we haven't assembled all the parts yet. Because the system is modelled after an FDA-approved cochlear device, we hope that it can move quickly into patients. In the second system, the electronics are actually mounted onto the array, which is connected to a fibre-optic cable. Both power and neural signals could be transmitted in and out via this cable. We hope to start tests of the implantable devices in monkeys this winter.

See the full Story via external site: www.technologyreview.com

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