Brain Implant Lets Quadriplegics Move Robotic Limbs

A new study looks at how paralyzed people are able to move robotic arms with their thoughts, due to a microchip that is implanted in their brains that sends neural signals to a computer. Robert Siegel speaks with the lead author of the study, Dr. Leigh Hochberg, neurologist and engineer at Brown University and the VA Medical Center in Providence, R.I.

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MELISSA BLOCK, HOST:

From NPR News, this is ALL THINGS CONSIDERED. I'm Melissa Block.

ROBERT SIEGEL, HOST:

And I'm Robert Siegel.

A new technology makes it possible for a quadriplegic to use only thought to move a robotic arm. According to a report out yesterday, a Massachusetts woman was one of two patients to use the arm. She picked up a bottle with coffee in it and drank it, using a straw. This is the first time in 15 years that she was able to feed herself.

And to explain how the technology works, we're joined now by Dr. Leigh Hochberg, who is a neurologist, an engineer and the lead author on this study. Welcome to the program.

DR. LEIGH HOCHBERG: Good afternoon. Thanks very much for having me.

SIEGEL: And first, I understand that the key here is a tiny sensor that's implanted in the subject's brain. What exactly is in there?

HOCHBERG: That's right, a tiny sensor that we refer to as an array of electrodes. It's about 4-by-4 millimeters. It's about the size of a baby aspirin and we tap that into a part of the brain called the motor cortex. And it's a very important part of the brain for the control of movement, for example, for the control of the arm or the hand.

SIEGEL: And this little sensor is actually taking the electricity in the brain and it's transmitting it?

HOCHBERG: It is. Each of those 96 little electrodes can record from one or more neurons or brain cells. And those neurons communicate through electrical activity, that's the language of the nervous system. So the array of electrodes listens to that electrical activity. It sends it down some fine wires to a - what we call a pedestal, which is really a plug that sits right on top of the head. And then, during our research sessions, we connect that plug via cable to some computers.

And the job of those computers is to, what we call, decode the neural activity that's associated with her when she thinks about moving her hand. And at the beginning of the research, we build essentially a map between the patient's own brain activity - that is the neural activity that we're recording from that little place in the cortex - and their intended movement.

SIEGEL: So, the impulses go from the woman to the computer, and then from the computer to the robotic arm?

HOCHBERG: Exactly. It goes to the computer to whatever assistive device we may have connected on that particular day. In this manuscript that was out today in Nature, it was connected to one of two robotic assistive devices.

SIEGEL: The picture of a woman using a robotic arm, knowing that she hasn't been able to do this in so many years - since she suffered a stroke - is very, very dramatic. Is the science behind it equally dramatic? Is it a huge leap that's happened here?

HOCHBERG: As you stated, she for nearly 15 years had been unable to use her own arm. And when she thought about using her arm and hand to reach out to pick up that thermos of coffee - a cinnamon latte, to be precise...

(SOUNDBITE OF LAUGHTER)

HOCHBERG: And she brought it to her mouth. She took a sip. To see the smile on her face at that moment was really a remarkable thing.

I'm pleased by this step in the science. And I think that it's very encouraging for a number of reasons. One is that her stroke had occurred nearly 15 years before these particular research sessions.

Which means that her motor cortex that was essentially disconnected from the rest of her body, as a result of the stroke, was still working, was still there, was still trying to send the same signals down to her arm. And those signals being present meant that we could harness them and allow her to reach out and control that robotic limb.

SIEGEL: Just another example of what the brain retains even after it's lost the ability to communicate with a limb.

HOCHBERG: Indeed.

SIEGEL: What's next? Would do you hope for most here?

HOCHBERG: We have a number of goals in the ongoing research. Both of our participants, say in this current paper, are known as what's locked in. They are not only unable to move their arms and their legs, but they're also unable to speak. So we hope that we can develop a neurally-based communication technology.

The real dream for the research though is for people with paralysis to one day reconnect brain to limb.

SIEGEL: Well, its fascinating research and fascinating thing that you've accomplished. And thank you for talking with us about it.

HOCHBERG: Thanks so much.

SIEGEL: That's Doctor Leigh Hochberg, a neurologist/engineer. He's a Brown University, also affiliated with the VA Medical Center in Providence and Massachusetts General Hospital. And we were talking about the news that a quadriplegic patient was able to move a robotic arm and drink coffee using it, merely by commanding it with thought.

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