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Two Paralyzed People Use Brain-Controlled Robotic Arms

BrainGate microelectrode array (Brown University)

BrainGate microelectrode array (Brown University)

Two stroke victims with tetraplegia — total loss of the use of limbs and torso — were able to control robotic arms with brain activity to reach, grasp, and use physical objects. The results of this study from the BrainGate project are reported today online in the journal Nature (paid subscription required).

The BrainGate project is a collaboration of researchers from Department of Veterans Affairs, Brown University, Massachusetts General Hospital, Harvard Medical School, and the German Aerospace Center (DLR). The results reported in Nature are part of a clinical trial of the BrainGate neural interface system, which implants a miniature electrode grid, about the size of a baby aspirin (pictured left), in the motor cortex — the part of the brain involved in voluntary movement — of the stroke victims.

The electrodes in the implant are close enough to individual neurons to record the neural activity associated with intended movement. An external computer translates the pattern of impulses from the population of neurons into commands to operate assistive devices. For the trial, those assistive devices are robotic arms developed by the DLR Institute of Robotics and Mechatronics and DEKA Research and Development Corp., to perform reaching and grasping tasks across a three-dimensional space.

Participants in the trial are a 58-year-old woman, known as S3, and a 66-year-old man, known as T2. Both individuals had been paralyzed by brainstem strokes years earlier which left them with no functional control of their limbs. Both S3 and T2 controlled the robotic arms to reach for and grasp foam targets that were placed in front of them using flexible supports.

S3 was also able to use the DLR arm to pick up a bottle of coffee, bring it to her mouth, issue a command to tip it, drink through a straw, and return the bottle to the table. Her BrainGate-enabled, robotic-arm control during the drinking task required a combination of two-dimensional movements across a table top plus a “grasp” command to either grasp and lift or tilt the robotic hand; see video below.

In the research, the robots acted as a substitute for each participant’s paralyzed arm. The robotic arms responded to the participants’ intent to move as they imagined reaching for each foam target. The robot hand, for example, grasped the target when the participants imagined a hand squeeze. Because the diameter of the targets was more than half the width of the robot hand openings, the task required the participants to exert precise control.

In 158 exercises using the DLR and DEKA robotic arms, both participants were able to touch the targets within the allotted times from just under half to more than two-thirds of the time. T2 touched the target with the DEKA arm 96 percent of the time.

T2, says Brown University, performed the session in this study on his fourth day of interacting with the DEKA arm. Using his eyes to indicate each letter, he later described his control of the arm: “I just imagined moving my own arm and the arm moved where I wanted it to go.”

The BrainGate neural interface system is being studied under an Investigational Device Exemption from the Food and Drug Administration. This exemption allows a device to be studied in a clinical trial  to collect safety and effectiveness data required to support a Premarket Approval application or a Premarket Notification submission to FDA.

“This paper reports an important advance by rigorously demonstrating in more than one participant that precise three-dimensional neural control of robot arms is not only possible, but also repeatable,” says John Donoghue, who directs the Brown Institute for Brain Science, and senior author of the paper. “We’ve moved significantly closer to returning everyday functions, like serving yourself a sip of coffee, usually performed effortlessly by the arm and hand, for people who are unable to move their own limbs.”

The following video tells more about the project and clinical trial.

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