Brain-Computer Link Aids Paralyzed Patient

In the first such experiment in humans, researchers say a quadriplegic patient with spinal cord injury produced brain signals that allowed him to shift a cursor on a computer screen.

Using signals picked up by a sensor implanted in his brain that were then translated into electronic impulses, the 25-year-old man was able to control a computer cursor that allowed him to manipulate mechanical devices.

Successful use of this "brain-computer interface device" is being hailed as an important breakthrough for those paralyzed by injury or disease.

"One of the most exciting findings is that one part of the brain -- the motor cortex that usually sends its signals down through the spinal cord to control movement -- can still be used by this patient to control an external device, even after the spinal cord injury," said lead researcher Dr. Leigh Hochberg, a neurologist at Massachusetts General Hospital.

The study utilized a new brain-computer interface device called the BrainGate Neural Interface System. It's in the early stages of clinical testing, Hochberg said.

His team reports the findings in the July 13 issue of Nature.

The patient under study is a 25-year-old man who suffered a knife wound in 2001 that cut his spinal cord at the neck, leaving his arms and legs paralyzed.

In the trial, the patient underwent 57 sessions over nine months, during which time the implanted BrainGate sensor recorded activity in his motor cortex while the man imagined moving his paralyzed limbs. He then used that "imagined motion" in several computer-based tasks.

Within little or no learning time, the patient began to be able to move a computer cursor via the device to open simulated e-mail, draw circular shapes and play simple video games. He also was able to open and close a prosthetic hand and use a robotic limb to grasp and move objects, the researchers said.

The findings may have implications for paralyzed patients everywhere. "In the short run, it may be possible for someone who can't use their arms or legs to regain control over their environment," Hochberg said. "In the long-run, using additional stimulation technology, they may be able to regain control over their own limbs," he added.

Hochberg see this as an important first step in helping paralyzed patients regain some control over their lives.

"This study suggests that the signals in the motor cortex are not only still there, but they can be modulated voluntarily to do things that are similar to what those cells were doing before," Hochberg said. "So, it is possible that someone who can't use their arms might be able to use the same cell in the motor cortex through a device like this to control a cursor on a computer screen and therefore improve their ability to control their environment."

Bijan Pesaran, an assistant professor of neural science at New York University's Center for Neural Science, called the finding "an exciting advance in the field of neural prostheses. For the first time, they show that the motor cortex of paralyzed human patients is still active years after a spinal cord injury."

"By simply imagining movements, their patient can use signals in the motor cortex to achieve effective prosthetic control. The next step will be to compare the performance and longevity of this device with other devices that use different signals and different brain areas involved in movement planning," Pesaran added.

In another study reported in the same issue of the journal, researchers at Stanford University say they've found a faster method of processing signals from the brain. The new technology could improve devices such as BrainGate.

"We found that it is possible to select targets, for example, keys on a keyboard, much more rapidly than previously believed," said senior author Krishna Shenoy, an assistant professor of electrical engineering and neuroscience.

The importance of the finding is that it will make it easier for patients to regain some independence, Shenoy said.

In their experiments, Shenoy's team worked with rhesus macaque monkeys. By identifying the brain waves the monkeys generated when they were only thinking about moving an arm, the researchers were able to find the optimum point for both speed and accuracy for the direction of the movement. This was then used to create a computer algorithm that can be used in neuro-prosthetic devices.

"We are really talking about a day where we can build interfaces with the brain," Shenoy said. "If it is a spinal cord injury, we can bypass it. If you're blind, we could write visual images into areas of the brain," he explained.

The difference in treating spinal cord injuries with stem cells or with a neuroprosthetic is that stem cells have the potential for a cure, Shenoy said. "What we are talking about isn't a cure, it's a remediation, it's a bypass," he said.

In a News and Views article in the same issue of Nature, one expert surveyed recent progress in neuroprosthetics.

Stephen H. Scott, from the Centre for Neuroscience Studies at Queens University, Kingston, Ontario, Canada, said these devices will probably do more than just help patients communicate. They may also help them regain control of important bodily processes such as bladder function, he said.

Whether this technology can actually help someone regain their ability to walk is more doubtful, Scott said.

"Are they going to be able to run an electric wheelchair? I think they could do that. It's possible they could drive a car. Getting them to walk is harder," he said.