Thursday, July 13, 2006

Brain Chips Give Paralyzed Patients New Powers

A neural implant allows paralyzed patients to control computers and robotic arms -- and, maybe one day, their own limbs.

By Emily Singer

Matthew Nagle, a 25-year-old man who was paralyzed after a knife wound in 2001, was the first person to test out a surgically implanted electrode array. (Credit: Joshua Paul.)

Neuroscientists dream of creating neural prosthetics that would allow paralyzed patients to regain control over their arms and legs. While that goal is still far off, researchers at Brown University and Massachusetts General Hospital are reporting a promising step forward.

In a study published in the journal Nature this week, the researchers describe how two paralyzed patients with a surgically implanted neural device successfully controlled a computer and, in one case, a robotic arm -- using only their minds.

[Click here to see videos of the patient controlling a computer cursor and a prosthetic hand.]

It is the first time such results have been achieved with neural implants in humans. The researchers are now refining the experimental system into a commercial product -- one that could help patients in their daily lives. They plan to make the device wireless and fully implantable and to improve the speed and complexity of movements that patients using the implant can perform.

"It's a landmark study because it shows that even years after injury, you can still record useful signals from the brain and use them to drive a device," says Joseph Pancrazio, program director for neural engineering research at the National Institutes for Neurological Disorders and Stroke in Bethesda, MD. "This group has really pushed the frontier."

During spinal-cord injuries and some types of stroke, the information relay system between the brain and muscles is disrupted. Neural devices, such as the one used in the study, aim to record and process existing signals and use them to control a computer cursor, robotic arm, or even paralyzed limb. The Brown/MGH researchers first implanted a brain chip in a human in June 2004. And while there have been signs of success since then, the Nature paper is the first peer-review publication describing in detail what paralyzed patients can do with the implant. (Technology Review reported on Donoghue's work with Nagle last year, in "Implanting Hope," March 2005.)

The brain-computer interface used in the study, made by Cyberkinetics Neurotechnology Systems in Foxborough, MA, consists of a tiny silicon chip containing 100 electrodes that record signals from hundreds of neurons in the motor cortex. A computer algorithm then translates this complex pattern of activity into a signal used to control an external device.

The first patient implanted with the device, a 25-year-old man who was paralyzed after a knife wound in 2001, successfully learned to control a computer cursor, moving adeptly through an e-mail program and using the computer to turn on a television and change the channel. When the device was hooked up to a robotic hand, he quickly learned to control the hand, picking up and dropping a piece of candy into a technician's hand. "It was exciting because he picked up on that very quickly -- around ten minutes," says John Donoghue, senior scientist on the project, founder of Cyberkinetics, and a neuroscientist at Brown University in Providence, RI. (Click here to see video of the patient controlling a computer cursor and a prosthetic hand.)