Mind control arm restores touch

Sense of touch drastically improves functionality of prosthetics

Washington, 21: Imagine being able to control a robotic arm from a distance, using only your mind. Now imagine being able to feel when its fingers grasp an object, as though it were your own hand.

US researchers published a study in the journal Science on Thursday about the world’s first brain-computer interface that allowed a volunteer with paralysis from the chest down to accomplish this very feat.

The team say their work demonstrates that adding a sense of touch drastically improves the functionality of prosthetics for quadriplegics, compared to having them rely on visual cues alone. “I am the first human in the world to have implants in the sensory cortex that they can use to stimulate my brain directly,” Nathan Copeland, 34, said.

“And then I feel as if a sensation is coming from my actual hand.”

In 2004, Copeland was in a car accident that left him with a serious spinal cord injury and without the use of his hands or his legs.

He volunteered to participate in scientific research, and six years ago underwent a major operation to have tiny electrodes implanted in his brain. Two sets of 88 electrodes the width of a strand of hair are arranged into “arrays” that resemble tiny hairbrushes and penetrate deep into the brain's motor cortex, which directs movement.

Fewer than 30 people in the world have these kinds of implants, the study's colead author Rob Gaunt, an assistant professor in the Department of Physical Medicine and Rehabilitation at the University of Pittsburgh, said. What’s unique about Copeland is an additional set of electrodes that are connected to his somatosensory cortex, which receives processes sensations.

“When we’re grabbing objects, we use this sense of touch very naturally to improve our ability to control,” explained Gaunt.

The team developed an interface that is “bi-directional” — meaning not only can it “read” instructions from the brain and send them to the artificial limb, it can also “write” sensations from the device and transmit them back.

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