skip navigation nih record
Vol. LXV, No. 10
May 10, 2013
cover

next story


My Robot, Myself
Body Re-engineering Leaps Toward the Future

On the front page...

Dr. Ralph Etienne-Cummings of Johns Hopkins

Dr. Ralph Etienne-Cummings of Johns Hopkins

Science is the superhero in this story. A recent Staff Training in Extramural Programs (STEP) forum in Lister Hill Auditorium invited experts in engineering, neurobiology and surgery to discuss progress in robotics, brain-machine interfaces and powered prosthetic limbs.

The cool factor was off the charts. Some highlights:

Building neurons in silica. To make fully neurally integrated prosthetics, said engineer Dr. Ralph Etienne-Cummings of Johns Hopkins University, we need to link thoughts to actions, sensors to feelings and to let the brain know where limbs and joints are in space.

“We are working towards…machines whose signaling and encoding are no different from what you find in the brain itself,” said Etienne-Cummings. “For that we have to go and look at nature and how it’s constructed.”

Continued...

How do you make a processing system to serve in a living body? The brain is not a simple organ. It has 100 billion neurons and each neuron can have 1,000-10,000 synapses—the connections between neurons. The nervous system uses electrical energy in “nerve impulses” to transmit messages from one cell to another.

Nerve cells operate using ions, which are electrically charged atoms. These move from inside the cell to outside the cell to generate these impulses.

To decode information for use in the body, mechanical layers were lab-created to mimic how nerve cells let ions flow. Thus an analog of neurological tissue was born.

The STEP panel includes Dr. Andrew Schwartz (l), Dr. Todd Kuiken (c) and Etienne-Cummings.

The STEP panel includes Dr. Andrew Schwartz (l), Dr. Todd Kuiken (c) and Etienne-Cummings.

“This is how we build computers that speak the same language as [the] brain,” said Etienne-Cummings. His audio track of peripheral touch fibers returning data to central processing sounded like percussion in a techno band.

The brain’s complexity cuts against quick results. This also applies to the eye, which is an elegant extension of the brain. Yet a prosthesis for the retina, the specialized tissue in the back of the eye, has already been FDA-approved. This artificial retina can help patients see, although not perfectly. A normal eye can see through sunglasses without a hitch, but no retinal prosthesis can do that. Not yet. In rat models, work on an upgrade is in process.

Turning to spinal circuits, “neurons below an injury are okay; they just can’t communicate with the brain,” said Etienne-Cummings. “We need a gait control system.” In a cat temporarily paralyzed by anesthesia, locomotion was restored with the help of a customized backpack.

“The cat walks a kilometer on a treadmill,” said Etienne-Cummings. “It’s unprecedented.”

High-performance neural prosthetics. Of the 54 million Americans with disabilities, more than 1.6 million are living with limb loss, caused by disease or trauma. By November 2012, U.S. armed service members wounded in Iraq and Afghanistan numbered more than 1,500 amputees. Hundreds of those suffered multiple limb amputations. Body armor saves the core, but not the limbs.

Schwartz discusses high-performance neural prosthetics, including robotic arms set in motion by thought.

Schwartz discusses high-performance neural prosthetics, including robotic arms set in motion by thought.

Photos: Ernie Branson

“The primate hand is amazingly complicated,” said neurobiologist Dr. Andrew Schwartz of the University of Pittsburgh. Fingertips are packed with nerve endings, and with its opposable thumb the hand can manipulate a world of objects. Hands also have the body’s greatest positioning ability. Besides our many daily tasks, we talk with our hands; we reassure each other with a touch.

In Schwartz’s model of how neurons fire when we move, implanted electrodes in the motion sensors of a monkey brain allowed the monkey to perform skillfully with his affected arm. And in humans? Schwartz played a clip of a woman with a degenerative disorder that left her paralyzed from the neck down and unable to feed herself. Scientists wired her up, strapped on a robotic arm and asked her to “imagine you’re moving.”

They could hear her neurons firing. And then, with her thoughts, she manipulated her robotic arm to grasp a piece of chocolate and eat, unassisted, for the first time in 13 years.

Building bionics. Physiatrist Dr. Todd Kuiken of the Rehabilitation Institute of Chicago spoke on current applications: “You just have to find the clinical heart of the problem and figure out what the patient wants to do.

“Muscle only stays alive a year if you cut a nerve away,” he explained. “Nerves stay alive [much longer]. If I have a World War II vet and tap a nerve, he’ll feel his missing hand.”

If neural signals still exist, then the patient’s remaining muscles, if healthy, can serve as biological amplifiers. Skin surface can record up to the millivolt range, which can allow a targeted reinnervation.

Kuiken builds bionics to solve clinical problems.

Kuiken builds bionics to solve clinical problems.

Consider the case of Jesse the Lineman, who sustained 7,200-volt burns and bilateral shoulder disarticulations, losing both arms down to the sockets. Now, after targeted reinnervation surgery, he has better muscle signals on his chest. These signals are wired to his prosthetic arm, and so to use his hand, he just has to think about using it, Kuiken said.

Other applications include a new custom-made version for women. “We build our own to the 25th percentile female average,” said Kuiken. “All are commercially available.”

Ninety percent of amputations involve legs, and of these, 90 percent are due to vascular disease (especially diabetes). The next generation of prosthetic legs, developed in an NIH-funded Vanderbilt University project, lets knee and foot move together, without foot drag.

During Q&A, Schwartz said, “For the past 30 to 40 years, scientists thought that one neuron does only one job. Now we know many neurons do many things. This is a tidal shift in how we think about the brain.”

If this sounds like a tale of superheroes, that’s not science fiction. That’s NIH-funded science.

This STEP forum is archived at http://videocast.nih.gov/summary.asp?Live=11930&bhcp=1.


back to top of page