Using computers for checking email, drawing images and playing games are common tasks for most people. For the severely paralysed, however, they're impossible.
Neurotechnology — using technology to study the brain — relies on methods such as CAT (computed axial tomography) scans and deep brain stimulation. In deep brain stimulation, medical devices are placed on the brain in an effort to control brain activity and aid another part of the body.
This use of neurotechnology can stop the tremors of people with Parkinson's disease, while cochlear devices can restore hearing. While these examples of neurotechnology insert information into the brain, other applications of the technology involve extracting information from brain signals via neural interfaces, or a communication link set up between a brain and a device, such as a computer. This field holds promise for helping paralysed people reconnect with the world.
For some people participating in a clinical trial of BrainGate, a neural interface system developed by Cyberkinetics Neurotechnology Systems of Foxborough, Massachusetts, that connection has already occurred.
"Many neurological disorders disrupt the ability to move, but leave cognition intact," said John Donoghue, founder, chief scientific officer and director of Cyberkinetics, during a recent talk on his company's technology at Boston's Museum of Science. "Think spinal cord injuries, something else that cuts the brain off from the body. The signals remain years after the injury."
Converting this cognition into action requires reading brain signals, which communicate messages from the brain to the nerves. Neurons, using electrical impulses, handle the task of sending communications from the brain to the body. These impulses resemble spikes when displayed on a monitor.
"All the information in the brain is based on these spikes putting out information," Donoghue said. "When you think movement, intention goes from the brain to nerves to muscles."
Of course, with paralysed patients, these intentions never develop into an action.
Cyberkinetics' technology decodes these electrical impulses into the corresponding action, with participants performing tasks such as moving a cursor or spelling out words on a monitor, all by thought. Picking up the brain's electrical impulses requires placing microelectrode sensors on the brain's motor cortex, a section of the cerebral cortex that controls motor functions.
The sensor, a square chip the size of a child's aspirin tablet, is placed on the brain via a hole that is drilled into the skull. The sensor, which contains 100 electrodes that are thinner than a human hair, is imbedded 1 millimeter into the brain.
"The only way to pick up signals is to place microelectrodes up close to our nerve cells," Donoghue said.
A bundle of gold wires connects the sensor to a pedestal, which protrudes through the scalp. Cables connect the pedestal to a cart containing a computer array, which analyses the brain data and translates it into a corresponding motion.
When connected to a PC, some patients in BrainGate's clinical trial have been able to check email by thinking about moving a cursor displayed on a monitor, as well as play a video game by thinking about moving an on-screen paddle. Another patient "spoke" for the first time after the person used a word processing program to form sentences.
BrainGate can also be connected to prosthetic devices and other peripherals. One patient opened and closed a prosthetic hand with thought, and picked up and moved objects with the aid of a robotic arm.
After 2,000 cumulative days of studying BrainGate's four participants, no safety-related concerns have surfaced, Donoghue said.
Donoghue noted that BrainGate is still in its infancy and is only being demonstrated. While he sees more ambitious uses for the technology, "we're a very long way from that", he said.
The movement BrainGate allows may not be fluid motions, but represents major advancements for paralysed people, he said. "This may not be an elegant motion, but to a person who can't do anything, we have the ability to give them some control," he said.
Future possible applications of the technology may include restoring limb movement by attaching BrainGate to motorized exoskeleton-like devices on a paralysed person's arms, for instance. As that person thought about moving an arm, BrainGate would translate those electrical impulses, relay motion intentions to the devices' motor and create movement.
While BrainGate's current uses involve helping the injured, in the future it could potentially find its way into healthy people, although that is a distant scenario, Donoghue said.
"There is the question of how to get information into the brain to instantly use it, like a language, but that is way, way out there," he said.
Donoghue hopes future incarnations of BrainGate's computer system will come in a streamlined, smaller and portable form capable of fitting on a wheelchair. The system's next generation of brain sensors may use wireless technology to transmit data from a patient to the computer array.
"We use infrared to go through the skin," he said. "It can be controlled. Radio frequency goes everywhere."
While some may question science being used in such a way, Donoghue said that severe injuries are not conditions people seek.
"People who are paralysed never not wish to be paralysed," he said. "I am convinced this is going to work. In the 1950s no one would have thought of placing wires in humans."