By Mark Henderson
Brain implants could allow quadriplegics enough control over their limbs to be able to feed themselves using their own hands, an expert in the technology has said
PATIENTS paralysed from the neck down will be able to feed themselves within the next five years using their own hands and arms, an expert has predicted.
John Donoghue, of Brown University in Rhode Island, is pioneering the technology necessary to make this possible.
Brain implants that have allowed quadriplegics to move computer cursors with the power of thought will soon be capable of stimulating patients’ own muscles, giving them enough control over their limbs to grasp and manipulate a spoon, he said.
The range of movement will be limited initially, but the technology has the potential to transform the lives of people with spinal cord injuries who are reliant on others to feed, wash and dress them. “They are not going to be writing or piano-playing, but it is a first step to proving a physical connection can be remade from the brain to the muscles,” Professor Donoghue told The Times.
“I’m quite optimistic it will be done within five years.”
The ambitious goal of bypassing spinal damage that causes paralysis has emerged from his team’s astounding success with a device called BrainGate, an aspirin-sized implant that records electrical signals from the part of the brain that processes movement in the limbs.
In July, the work received world acclaim when details of the first two patients to be fitted with the device were published in the journal Nature.
One, Matt Nagle, 25, from Massachusetts, learnt in just nine months to use it to move a cursor, open e-mails, play computer games and even operate a simple robotic arm. The other, an unnamed 55-year-old man from Chicago, also had some success at controlling a cursor before signals from the device were lost.
Further evidence for BrainGate’s potential has now come from results with two more patients, whose cases Professor Donoghue reported yesterday at the Society for Neuroscience conference in Atlanta.
The first was a 53-year-old woman who developed “locked-in” syndrome after a stroke in her brain stem left her unable to move any part of her body other than her neck and eyes: she is quadriplegic and cannot speak. The implant has allowed her to communicate more freely, by moving a cursor over a virtual keyboard. Previously, her only option was to use an “eyeboard”: she would stare at a letter until a helper worked out which one it was.
The second patient was a man with amyotrophic lateral sclerosis (ALS), the form of motor neuron disease that affects Steven Hawking, who also learnt to control a cursor. This has surprised many scientists, who had assumed that the brain damage involved in the disease might make this impossible.
Professor Donoghue is now researching ways of refining BrainGate’s software to give patients finer control, and of linking it to an existing technology, functional electrical stimulation (FES), that can move paralysed muscles.
FES uses electricity to prompt muscles to tense and relax artificially, and has already been used in about 300 patients with more limited paralysis. One patient who is paralysed from the waist down, for example, has an FES device that allows her to stand up. The principle is similar to abdominal stimulators used to improve muscle tone.
Professor Donoghue is now working with FES specialists at Case Western Reserve University in Cleveland to use BrainGate signals to switch FES devices on and off in a patient’s arm, so that it can be moved independently.
“Our plan is to hook BrainGate up to an FES system, and we envision it will take five years,” he said. “Our plan is to have a tetraplegic patient with an arm supported by an orthotic, with the elbow and hand controlled by the brain via an FES system. Our goal is for a patient to grasp a spoon and feed themselves. Given what we have seen with BrainGate, we think this should be possible. It is still early, but we just need to hook the two together to achieve a modest kind of movement.”
Even though this would only allow very stilted movement, it would greatly improve the quality of life of people paralysed from the neck down, he said. Using a patient’s own arm would also be superior to using a robotic prosthesis.
“If you ask tetraplegics what they most want to be able to do, and offer them an inelegant way of feeding themselves or a robot that will feed them, they would rather have the independence,” he said. “One guy said to me, ‘I just want to scratch my nose.’ The simple things they want most may not require extraordinarily sophisticated technology. For people who are unable to communicate verbally because of stroke or ALS, it allows them to type a message. If they can electronically type it is much more efficient. It can also use predictive software. We can have people write out a description of all their medical problems and symptoms for a physician.”
In the longer term, BrainGate could potentially be used to establish more sophisticated muscle control, and it might also be used in diagnosis and even treatment of other neurological disorders. As the device effectively takes recordings from particular areas of the brain, it could also be used to monitor epilepsy patients for warning signs of a seizure.
“BrainGate could detect a pattern developing to predict a seizure,”
Professor Donoghue said. “You might be driving, and it would predict a seizure in one hour, so you could pull off the road and make sure you don’t engage in any dangerous behaviour.”HOW TO BYPASS THE SPINAL-CORD
BrainGate uses a 4mm-square sensor, from which 100 hair-thin electrodes protrude into the brain. These pick up electrical signals from the neurons
The sensor is attached to the part of the brain’s motor cortex that would control the patient’s arm if he still had the ability to move his limbs
The signals are then fed into a computer, which processes the spikes of activity to decode the patient’s intentions. By “thinking left” or “thinking right” the patient can thus move a computer cursorControl is not as precise as it would be with a hand-operated mouse, but researchers are working to refine the decoding software
In the first trials, patients have used this to open emails, play computer games and even operate a simple robotic arm, all while holding a conversation, showing that complete concentration is unnecessary
Functional Electrical Stimulation (FES) devices can manipulate muscles artificially using electrical signals
The next step will be to devise a way of allowing the BrainGate chip to “talk” to an FES device attached to a patient’s own arm, so he or she can control it
Electrical signals generated by the brain would use BrainGate to bypass the patient’s damaged spinal cordCopyright 2006 Times Newspapers Ltd.