Computer brain implants may help paralyzed move again

Dec 28 2011 - 2:12pm

It sounds like science fiction, but scientists around the world are getting tantalizingly close to building the mind-controlled prosthetic arms, computer cursors and mechanical wheelchairs of the future.

Researchers already have implanted devices into primate brains that let them reach for objects with robotic arms. They've made sensors that attach to a human brain and allow paralyzed people to control a cursor by thinking about it.

In the coming decades, scientists say, the field of neural prosthetics -- of inventing and building devices that harness brain activity for computerized movement -- is going to revolutionize how people who have suffered major brain damage interact with their world.

"Medicine has not taken neural prosthetics very seriously until recently," said Dr. Edward Chang, a University of California, San Francisco neurosurgeon and co-director of the Center for Neural Engineering and Prostheses at University of California, Berkeley and UCSF. "But it's become clear in the last five to 10 years that there are some practical applications."

Jose Carmena, a neuro-engineer at UC Berkeley and Chang's co-director, puts his thoughts more succinctly: "There's going to be an explosion in neural prosthetics."

The joint UC Berkeley and UCSF center started a year ago to take advantage of the neurology expertise in San Francisco and the engineering skills across the bay.

Such devices that allow the brain to control a device aren't entirely new. Aside from some small steps made at other institutions -- the brain-controlled computer cursor, for example -- there's the cochlear implant, the first neural prosthetic tool developed and the only one that's ever seen wide use.

The cochlear implant, which was invented at UCSF in the 1970s, intercepts sounds as electrical signals and then sends those signals directly to the brain, bypassing the damaged nerves that caused hearing loss. The devices being developed today work under the same premise but are much more complex.

Over the past decade, scientists have made leaps of progress in learning how to read and decode the millions of electronic impulses that fire between neurons in the brain, controlling how our bodies move and how we see, feel and relate to the world around us.

"We don't have existing electronics to be able to process in real time dozens of channels from the brain," Chang said. "It turns out we need a lot of information from the brain to work."

The neural prosthetic devices that are just in their infancy now work by connecting a device inserted into the brain directly to a computer. The signals from the brain, in the form of electrical impulses, travel through a cable to the computer, where they are decoded into instructions for some kind of action, like moving a cursor.

But for a neural prosthetic device to actually be useful, it would have to be transplanted near or in the brain and transmit wireless signals to a device like a robotic arm. It would need to be able to last forever -- or at least a lifetime -- on batteries that never have to be changed and won't damage the brain.

Scientists say the actual technology is only one problem.

"Some of the problems are purely technical, like how do you record from hundreds and hundreds of neurons at the same time," said Philip Sabes, a neuroscientist at the Keck Center for Integrative Neuroscience at UCSF.

It's possible that a surface device could collect enough information to be useful in controlling a neural prosthesis with much less risk to the patient.

But it may be that scientists need to implant a device into the brain to collect enough of the brain signals, especially for creating a prosthetic device that feels natural -- a robotic arm, perhaps, that can sense hot and cold, or the difference between a wine glass and a coffee mug.

"You want the arm to feel like it's a part of you, not this thing you're picking up," Sabes said. "It will increase the sense of ownership of the device."

(Contact Erin Allday at eallday(at)sfchronicle.com.)

(Distributed by Scripps Howard News Service, www.scrippsnews.com.)

 

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