Monkey Brain

May 29, 2008 at 3:17 pm 2 comments

Monkey brain, robot arm

Monkeys… Sitting in a chair… Using an arm-like machine to grab marshmallows… And controlling this machine with their brains.


Scientists have made a quantum-leap in brain-machine interface technology, according to a new article in the the journal Nature. In “Cortical control of a prosthetic arm for self-feeding,” researchers from the University of Pittsburgh and Carnegie Mellon University built an arm-like machine, complete with “shoulder joints, an elbow and a grasping claw with two mechanical fingers” and then gave two macaques joysticks that could control the mechanical arm.

Then, as explained by Benedict Carey, in a great article for the International Herald Tribune:

Just beneath the monkeys’ skulls, the scientists implanted a grid about the size of a large freckle. It sat on the motor cortex, over a patch of cells known to signal arm and hand movements. The grid held 100 tiny electrodes, each connecting to a single neuron, its wires running out of the brain and to a computer.

The computer was programmed to analyze the collective firing of these 100 motor neurons, translate that sum into an electronic command and send it instantaneously to the arm, which was mounted flush with the left shoulder.

The scientists used the computer to help the monkeys move the arm at first, essentially teaching them with biofeedback.

After several days, the monkeys needed no help. They sat stationary in a chair, repeatedly manipulating the arm with their brain to reach out and grab grapes, marshmallows and other nuggets dangled in front of them. The snacks reached the mouths about two-thirds of the time — an impressive rate, compared with earlier work.

The monkeys learned to hold the grip open on approaching the food, close it just enough to hold the food and gradually loosen the grip when feeding.

On several occasions, a monkey kept its claw open on the way back, with the food stuck to one finger. At other times, a monkey moved the arm to lick the fingers clean or to push a bit of food into its mouth while ignoring a newly presented morsel.

The animals were apparently freelancing, discovering new uses for the arm, showing “displays of embodiment that would never be seen in a virtual environment,” the researchers wrote.

This is radical research, leading to technology that will “allow people with spinal cord injuries and other paralyzing conditions to gain more control over their lives. Brain-controlled prosthetics are technically within reach.”

Click here to view a video of a monkey controlling a robot arm with using its brain activity.

Play, think…
J.R. Atwood 


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2 Comments Add your own

  • 1. Marshmallows as a study of self-control « playthink  |  September 18, 2009 at 5:07 pm

    […] Jonah Lehrer’s fascinating New Yorker article, “Don’t! The secret of self-control” explains that children who are able to pass the marshmallow test enjoy greater success in life. The above video is a reenactment of Mischel’s test from the 1960s. Marshmallows were also used by researchers studying brain-machine interface technology and the cortical control of a prosthetic arm for self-feeding. […]

  • 2. Kelly Kinnard  |  July 29, 2010 at 9:49 am

    How wonderful to gain knowledge about human medical problems through the torture and confinement of animals. Of course you’d use monkeys because they are the closest animals to humans that exist – oh my – does that mean they have feelings, thoughts, and relationships? Lock them in cold metal cages, strap them in chairs and make their limbs immobile for your own benefit. It appears the monkeys have more of a soul than the humans who subject them to such atrocious testing. Good job.


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Jason R. Atwood

I'm an avid trail runner and doctoral student at U.C. Berkeley who studies motivation and the relationship between the mind and body. This blog is a forum to share research, news, and musings about these topics of interest. More

Play is the beginning of knowledge.

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