The five-year goal for another company is to have a tetraplegic hold a spoonful of food and bring it up to his mouth. BrainGate is a brain-computer interface that also senses signals from the brain and transforms them into action. But Cyberkinetics Neurotechnology Systems Inc., Foxboro, Mass., is using its device to generate motor commands.
Its system is comprised of an implanted sensor, a decoder or translator, and a human interface. The sensor is a 4 × 4-mm silicon array with 100 hair-like electrodes. It is implanted onto the surface of the brain where motor commands are generated, specifically arm motor commands. “The sensor detects impulses from a few dozen to 150 cells,” says John Donoghue, founder and Chief Scientific Officer of Cyberkinetics. One hundred gold wires extend from the array to a pedestal which extends through the scalp. The pedestal is connected by an external cable to what are typically called “assistive technologies,” or devices such as a computer or robotic arm.
Cyberkinetics is running two studies, one for people paralyzed from spinal cord injuries or brain-stem strokes and one for people with ALS, or Lou Gehrig's disease. “We have people initially look at a computer cursor that we're moving on the screen and tell them to imagine they are moving it,” says Donoghue. “As they do that their brain cells change activity patterns. We map the relationship between that pattern of activity and the motion of the cursor. With a few quick practice blocks we build up a relationship that's quite reliable. And we map the firing pattern onto the cursor motion.”
The results are promising. Patients can control a simple computer interface to open e-mail, change the TV channel, or turn lights on and off. “We've demonstrated they can open and close a robotic hand, and control a robotic arm. One patient could operate an electric wheelchair. She wasn't sitting in the chair but she was directing it around the room. We're just not yet to the point where these are everyday operations,” he adds.
The current device has a pedestal and is connected through the skin, so the patient is tethered to a computer through a cable. “We're working on a fully-implantable wireless system. This will let the patient be mobile, and get rid of the percutaneous connector that passes through the skin,” he adds. But that's going to take some time to develop. “We wanted to be sure the initial indications are that the concept would work.”
Donoghue says the BrainGate could one day give patients as many functions as a normal hand. “We're working on taking signals from patients, particularly spinal cord injuries, and returning them through the body to a stimulator hooked up to muscles,” he says. In other words, researchers could fully repair someone.
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