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VIDEO: Neural-Machine Interface Moves Bionic Arm By User’s Thoughts

Breakthrough bionic gives sensory feedback to allow amputees to perform everyday movements

A bionic arm that allows users to think, behave and function as if there had never been an amputation has been developed by an international research team.

“We modified a standard-of-care prosthetic with this complex bionic system which enables wearers to move their prosthetic arm more intuitively and feel sensations of touch and movement at the same time,” said lead investigator Paul Marasco.

“These findings are an important step towards providing people with amputation with complete restoration of natural arm function,” said Marasco, who teaches at the Cleveland Clinic Lerner Research Institute’s Department of Biomedical Engineering.

Marasco and fellow researchers published the findings of their small study in the Sept. 1 edition of Science Robotics. Patients with traditional prosthetics cannot feel with their limbs and thus behave differently than people without an amputation while completing ordinary tasks, Marasco said. They must constantly be careful when using their prosthetic and often have difficulty learning from mistakes when applying varying degrees of force with their prosthetic hand.

The researchers said they were excited to see that those with a bionic arm could make calculated decisions and correct any mistakes just like non-amputees.

“With the new bionic limb, people behaved like they had a natural hand. Normally, these brain behaviors are very different between people with and without upper limb prosthetics,” Marasco said.

The two participants in the study had upper limb amputations and had previously undergone targeted sensory and motor reinnervation. The procedure establishes a neural-machine interface by redirecting amputated nerves to remaining skin and muscles.

A participant at Cleveland Clinic with her advanced prosthetic arm that feels grip movement sensation, touch on the fingertips and is controlled intuitively by thinking. She is wearing reflective markers on her arms and body that help a computer see her movements in a 3D environment. Her glasses allow a computer to see exactly what her eyes are looking at in the space around her. (Cleveland Clinic)

The participants were able to perform tasks that require ordinary hand and arm functionality. Using their newly developed evaluation tool, the researchers measured how users of the bionic arm fared in comparison to non-disabled people and those who have traditional prosthetics. Researchers also compared how users of the advanced prosthetic performed when the three sensory and motor modalities were enabled together versus individually.

“Over the last decade or two, advancements in prosthetics have helped wearers to achieve better functionality and manage daily living on their own,” said Marasco. “For the first time, people with upper limb amputations are now able to again ‘think’ like an able-bodied person, which stands to offer prosthesis wearers new levels of seamless reintegration back into daily life.”

Cleveland Clinic researchers adjust the bionic arm system that provides a study participant with the perception of grip kinesthesia through her neural-machine interface. (Cleveland Clinic)

In targeted sensory reinnervation, touching the skin with small robots activates sensory receptors that enable patients to perceive the sensation of touch. When the patients will their limbs to move, the innervated muscles communicate with a computerized prosthesis to move as the patients wish. Small but powerful robots vibrate kinesthetic sensory receptors in those same muscles to give the sensation that the prosthetic hand and arm are moving.

With the new artificial arm and advanced evaluation tools, the brain and behavioral strategies of the study’s participants matched those of non-amputees. No longer did they need to watch their prosthesis, as they could also find things without looking and effectively correct their mistakes.

Edited by Richard Pretorius and Kristen Butler