Monkey See, Robot Do

April 1, 2008
Monkey muse: Robot responds to primate brain signals

Monkey muse: Robot responds to primate brain signals. Masafumi Yamamoto, The New York Times / Redux

In a first-of-its-kind experiment, the brain activity of a monkey has been used to control the real-time walking patterns of a robot halfway around the world.

The experiment was a joint effort between a team from Duke Medical Center and researchers at the Computational Brain Project of the Japan Science and Technology Agency. The researchers say the technology they are developing could one day help those with paralysis regain the ability to walk.

"This is a breakthrough in our understanding of how the brain controls the movement of our legs, which is vital information needed to ultimately develop robotic prosthesis," says senior study investigator Miguel Nicolelis, Anne W. Deane Professor of neuroscience at Duke.

Monkey muse: Nicolelis monitors 
experiment from his Duke lab

Monkey muse: Nicolelis monitors experiment from his Duke lab. Photo: Jeremy M. Lange, The New York Times / Redux

Researchers implanted electrodes in the brains of two rhesus monkeys to capture the activity of hundreds of brain cells located in the animals' motor and sensory cortexes. They measured how the cells responded as each monkey walked on a treadmill at a variety of speeds, forward and backward. At the same time, sensors on the monkeys' legs tracked their movements.

Using mathematical models, the researchers were able to analyze the relationship between leg movement and brain-cell activity to determine how well the information gathered from the brain cells was able to predict the exact speed of movement and stride length of the legs.

The researchers were then able to transmit the motor commands from a monkey to the robot in Japan. As a result, Nicolelis says, the monkey and the robot were able to "walk in complete synchronization."

Even more amazing, Nicolelis says, is that when the monkey stopped walking, "it was able to sustain the locomotion of the robot for a few minutes—just by thinking" while watching a live video of the robot walking.

The experiment built on earlier work conducted by Nicolelis' laboratory in which monkeys were able to control the reaching and grasping movements of a robotic arm with only their brain signals. The researchers are estimating that work will begin within the next year to develop prototypes of the robotic leg braces for potential use with humans.