(NYT) Monkey’s Thoughts Propel Robot

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http://www.nytimes.com/2008/01/15/science/15robo.html?ref=todayspaper

 

January 15, 2008

Monkey’s Thoughts Propel Robot, a Step That May Help Humans

By SANDRA BLAKESLEE

If Idoya could talk, she would have plenty to boast about.

 

On Thursday, the 12-pound, 32-inch monkey made a 200-pound, 5-foot humanoid

robot walk on a treadmill using only her brain activity.

 

She was in North Carolina, and the robot was in Japan.

 

It was the first time that brain signals had been used to make a robot walk,

said Dr. Miguel A. L. Nicolelis, a neuroscientist at Duke University whose

laboratory designed and carried out the experiment.

 

In 2003, Dr. Nicolelis’s team proved that monkeys could use their thoughts alone

to control a robotic arm for reaching and grasping.

 

These experiments, Dr. Nicolelis said, are the first steps toward a brain

machine interface that might permit paralyzed people to walk by directing

devices with their thoughts. Electrodes in the person’s brain would send signals

to a device worn on the hip, like a cell phone or pager, that would relay those

signals to a pair of braces, a kind of external skeleton, worn on the legs.

 

“When that person thinks about walking,” he said, “walking happens.”

 

Richard A. Andersen, an expert on such systems at the California Institute of

Technology in Pasadena who was not involved in the experiment, said that it was

“an important advance to achieve locomotion with a brain machine interface.”

 

Another expert, Nicho Hatsopoulos, a professor at the University of Chicago,

said that the experiment was “an exciting development. And the use of an

exoskeleton could be quite fruitful.”

 

A brain machine interface is any system that allows people or animals to use

their brain activity to control an external device. But until ways are found to

safely implant electrodes into human brains, most research will remain focused

on animals.

 

In preparing for the experiment, Idoya was trained to walk upright on a

treadmill. She held onto a bar with her hands and got treats — raisins and

Cheerios — as she walked at different speeds, forward and backward, for 15

minutes a day, 3 days a week, for 2 months.

 

Meanwhile, electrodes implanted in the so-called leg area of Idoya’s brain

recorded the activity of 250 to 300 neurons that fired while she walked. Some

neurons became active when her ankle, knee and hip joints moved. Others

responded when her feet touched the ground. And some fired in anticipation of

her movements.

 

To obtain a detailed model of Idoya’s leg movements, the researchers also

painted her ankle, knee and hip joints with fluorescent stage makeup and, using

a special high speed camera, captured her movements on video.

 

The video and brain cell activity were then combined and translated into a

format that a computer could read. This format is able to predict with 90

percent accuracy all permutations of Idoya’s leg movements three to four seconds

before the movement takes place.

 

On Thursday, an alert and ready-to-work Idoya stepped onto her treadmill and

began walking at a steady pace with electrodes implanted in her brain. Her

walking pattern and brain signals were collected, fed into the computer and

transmitted over a high-speed Internet link to a robot in Kyoto, Japan.

 

The robot, called CB for Computational Brain, has the same range of motion as a

human. It can dance, squat, point and “feel” the ground with sensors embedded in

its feet, and it will not fall over when shoved.

 

Designed by Gordon Cheng and colleagues at the ATR Computational Neuroscience

Laboratories in Kyoto, the robot was chosen for the experiment because of its

extraordinary ability to mimic human locomotion.

 

As Idoya’s brain signals streamed into CB’s actuators, her job was to make the

robot walk steadily via her own brain activity. She could see the back of CB’s

legs on an enormous movie screen in front of her treadmill and received treats

if she could make the robot’s joints move in synchrony with her own leg

movements.

 

As Idoya walked, CB walked at exactly the same pace. Recordings from Idoya’s

brain revealed that her neurons fired each time she took a step and each time

the robot took a step.

 

“It’s walking!” Dr. Nicolelis said. “That’s one small step for a robot and one

giant leap for a primate.”

 

The signals from Idoya’s brain sent to the robot, and the video of the robot

sent back to Idoya, were relayed in less than a quarter of a second, he said.

That was so fast that the robot’s movements meshed with the monkey’s experience.

 

An hour into the experiment, the researchers pulled a trick on Idoya. They

stopped her treadmill. Everyone held their breath. What would Idoya do?

 

“Her eyes remained focused like crazy on CB’s legs,” Dr. Nicolelis said.

 

She got treats galore. The robot kept walking. And the researchers were

jubilant.

 

When Idoya’s brain signals made the robot walk, some neurons in her brain

controlled her own legs, whereas others controlled the robot’s legs. The latter

set of neurons had basically become attuned to the robot’s legs after about an

hour of practice and visual feedback.

 

Idoya cannot talk but her brain signals revealed that after the treadmill

stopped, she was able to make CB walk for three full minutes by attending to its

legs and not her own.

 

Vision is a powerful, dominant signal in the brain, Dr. Nicolelis said. Idoya’s

motor cortex, where the electrodes were implanted, had started to absorb the

representation of the robot’s legs — as if they belonged to Idoya herself.

 

In earlier experiments, Dr. Nicolelis found that 20 percent of cells in a

monkey’s motor cortex were active only when a robotic arm moved. He said it

meant that tools like robotic arms and legs could be assimilated via learning

into an animal’s body representation.

 

In the near future, Idoya and other bipedal monkeys will be getting more

feedback from CB in the form of microstimulation to neurons that specialize in

the sense of touch related to the legs and feet. When CB’s feet touch the

ground, sensors will detect pressure and calculate balance. When that

information goes directly into the monkeys’ brains, Dr. Nicolelis said, they

will have the strong impression that they can feel CB’s feet hitting the ground.

 

At that point, the monkeys will be asked to make CB walk across a room by using

just their thoughts.

 

“We have shown that you can take signals across the planet in the same time

scale that a biological system works,” Dr. Nicolelis said. “Here the target

happens to be a robot. It could be a crane. Or any tool of any size or

magnitude. The body does not have a monopoly for enacting the desires of the

brain.”

 

To prove this point, Dr. Nicolelis and his colleague, Dr. Manoel Jacobsen

Teixeira, a neurosurgeon at the Sirio-Lebanese Hospital in São Paulo, Brazil,

plan to demonstrate by the end of the year that humans can operate an

exoskeleton with their thoughts.

 

It is not uncommon for people to have their arms ripped from their shoulder

sockets during a motorcycle or automobile accident, Dr. Nicolelis said. All the

nerves are torn, leaving the arm paralyzed but in chronic pain.

 

Dr. Teixeira is implanting electrodes on the surface of these patients’ brains

and stimulating the underlying region where the arm is represented. The pain

goes away.

 

By pushing the same electrodes slightly deeper in the brain, Dr. Nicolelis said,

it should be possible to record brain activity involved in moving the arm and

intending to move the arm. The patients’ paralyzed arms will then be placed into

an exoskeleton or shell equipped with motors and sensors.

 

“They should be able to move the arm with their thoughts,” he said. “This is

science fiction coming to life.”