Moving a Robotic Arm With Just a Thought
Reaching for out cup of coffee or moving a computer mouse is easy for most of us. But for Tim Hemmes, who became paralyzed in a motorcycle accident, it was a heartfelt moment for him to be able to reach out to his girlfriend for the first time in 7 years through a thought-controlled robotic arm.
Scientists and doctors of University of Pittsburgh School of Medicine conducted the study with Hemmes to see if a person with spinal cord injury could move an external apparatus using their thoughts. The brain-controlled prosthetic arm system uses a brain-computer interface similar to the one we saw a few days ago with monkeys moving and feeling with virtual arms.
A postage stamp-sized electrocorticography grid, adapted from seizure-mapping brain electrode arrays, was surgically placed on the motor cortex of Hemmes’s brain. The surgeons ran wires from the chip under the skin of Hermes’s neck to exit at his upper chest so it could hook up with computer cables.
For the next four weeks Hemmes would connect the neurons of his motor cortex to a computer that would learn to recognize motion from his thought patterns. To do this, Hemmes was given test to move a ball to a zone on a 2D plane and eventually moved up to interacting in a 3D space. At first, Hemmes would think of body motions to move the ball; for example, bending his elbow to move right or wiggling his thumb to go left.
Later, Hemmes was able to just mentally visualize where he wanted the ball to go and complete the tasks without any computer assistance. This ability for “100 percent brain control” eventually allowed Hemmes to complete the same tasks with the robotic arm.
The team is gearing up for the next step of its research by recruiting people for a trial of a new electrode grid that can listen to individual neurons. They also plan to use two grids so that the patient can control arm movements and fine hand motions. The team also hopes that the technology could go wireless or even have brain-computer interfaces connect with muscle stimulating devices attached the paralyzed person’s own limbs.
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