Sans Hand

In a world first, doctors in Sweden say they’ve wired a prosthetic hand directly into a woman’s nervesallowing her to move its fingers with her mind and even feel tactile sensations.

The hand is an enormous step up from existing prostheses, which often rely on electrodes placed on the outside of the skin — and it could herald a future in which robotic devices interface seamlessly with our bodies.

Nerve Case

Researchers at Chalmers University of Technology and biotech firm Integrum AB created the prosthetic hand as part of DeTOP, an ambitious European research program on prosthetic limbs.

Surgeons anchored the hand to the woman’s forearm bones using titanium implants. They connected an array of 16 electrodes directly to her nerves and muscles, allowing her to control the hand with her mind — and, according to photos, use it to tie shoelaces and type on a laptop computer.

“The breakthrough of our technology consists on enabling patients to use implanted neuromuscular interfaces to control their prosthesis while perceiving sensations where it matters for them, in their daily life,” Chalmers researcher Ortiz Catalan said in a press release.

Virtual Light

Electronics wired straight into a human nervous system allow for mind-bending new ways to interact with technology. A video released by the Swedish researchers even shows the woman using the implant to flex a virtual hand on a computer screen — before the actual physical hand was installed.

For decades, cyborg limbs like those depicted in “Star Wars” or “Neuromancer” seemed relegated to the realm of science fiction. New research shows that they’re already here — just not yet widely available.

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Woman is given first robotic hand that allows user to touch and feel

The battery-powered limb could be available on the NHS within a few years, British researchers say

By Martin Bagot Health And Science Correspondent

(Image: Dr Max Ortiz Catalan)

The first robotic hand that enables the amputee to touch and feel has been given to a Swedish woman.

The revolutionary mechanical limb is controlled by electrodes connected to nerves and muscles in the stump

Signals pass “tactile sensations” to the nerves while allowing the body to control a range of motions similar to a real hand.

British researchers involved in the EU-funded project say the battery-powered limb could be available on the NHS within a few years.

The prosthetic could soon be available on the NHS (Image: PA)

Dr Luca Citi, of Essex University, said: “This is a big thing. Currently amputees would have to watch their prosthetic hand if they are picking up, say a plastic cup, to check they are not crushing it.

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Researchers demonstrate key to success of nerve transfer technique in bionic reconstruction

Modern prostheses offer patients who have had a hand amputated much greater capability in everyday life than was possible with previous prosthetic reconstructive techniques. Redundant nerves from the amputated extremity can be surgically transferred to provide a much better connection between the patient’s body and the prosthesis. This technique has proven to be successful, although the specific reasons for its success were not fully understood. A team of researchers led by Konstantin Bergmeister and Oskar Aszmann from the Division of Plastic and Reconstructive Surgery and the Christian Doppler Laboratory for Recovery of Limb Function at MedUni Vienna, demonstrated, in an animal model, that the key to success lies in the muscle undergoing a change of identity triggered by the donor nerve.

Bionic prostheses are mentally controlled, in that they register the activation of residual muscles in the limb stump. Theoretically it should be possible for the latest generation prostheses to execute the same number of movements as a healthy human hand. However, the link between man and prosthesis is not yet capable of controlling all mechanically possible functions, because the interface between man and prostheses is limited in terms of signal transmission. “If we could solve this problem, the latest prostheses could actually become an intuitively operated replacement that functions just like a human hand,” underscore the researchers.

To enable the prosthesis to move at all, nerves have to be surgically transferred during the amputation procedure to increase the total number of muscle control signals. This involves connecting amputated peripheral nerves to residual muscles in the amputation stump. This method is very successful, because these muscles regenerate after a few months to provide better control of the prosthesis. However, until now, it was not clear what specific changes this nerve transfer technique produces in muscles and nerves.

Previously unknown neurophysiological effects discovered

As part of an experimental study conducted over several years, a research team led by Konstantin Bergmeister and Oskar Aszmann from MedUni Vienna’s Division of Plastic and Reconstructive Surgery (Head: Christine Radtke) and Christian Doppler Laboratory for Recovery of Limb Function have now shown that this nerve transfer technique has previously unidentified neurophysiological effects. These result in more accurate muscle contractility and much more finely controlled muscle signals than previously thought.

It was also found that muscles take on the identity of the donor nerves, that is to say the function of the muscle from which the nerve was originally harvested. This means that muscles can be modified very specifically to achieve the desired control of the lost extremity. This information will now be used in follow-up studies to refine the surgical technique of nerve transfer and adapt it more accurately to fine control systems. The vision of an intuitively controlled prosthesis that can perform all the natural manual functions could become a reality within the next few years.


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Vibrations Restore Sense of Movement in Prosthetics

Scientists recreate proprioception for people with artificial arms using a perceptual illusion.

Sep 1, 2018



When Amanda Kitts’s car was hit head-on by a Ford F-350 truck in 2006, her arm was damaged beyond repair. “It looked like minced meat,” Kitts, now 50, recalls. She was immediately rushed to the hospital, where doctors amputated what remained of her mangled limb.

While still in the hospital, Kitts discovered that researchers at the Rehabilitation Institute of Chicago (now the Shirley Ryan AbilityLab) were investigating a new technique called targeted muscle reinnervation, which would enable people to control motorized prosthetics with their minds. The procedure, which involves surgically rewiring residual nerves from an amputated limb into a nearby muscle, allows movement-related electrical signals—sent from the brain to the innervated muscles—to move a prosthetic device.

Kitts immediately enrolled in the study and had the reinnervation surgery around a year after her accident. With her new prosthetic, Kitts regained a functional limb that she could use with her thoughts alone. But something important was missing. “I was able to move a prosthetic just by thinking about it, but I still couldn’t tell if I was holding or letting go of something,” Kitts says. “Sometimes my muscle might contract, and whatever I was holding would drop—so I found myself [often] looking at my arm when I was using it.”

What Kitts’s prosthetic limb failed to provide was a sense of kinesthesia—the awareness of where one’s body parts are and how they are moving. (Kinesthesia is a form of proprioception with a more specific focus on motion than on position.) Taken for granted by most people, kinesthesia is what allows us to unconsciously grab a coffee mug off a desk or to rapidly catch a falling object before it hits the ground. “It’s how we make such nice, elegant, coordinated movements, but you don’t necessarily think about it when it happens,” explains Paul Marasco, a neuroscientist at the Cleveland Clinic in Ohio. “There’s constant and rapid communication that goes on between the muscles and the brain.” The brain sends the intent to move the muscle, the muscle moves, and the awareness of that movement is fed back to the brain (see “Proprioception: The Sense Within,” The Scientist, September 2016).

GOOD VIBRATIONS: The prosthetic makes use of a kinesthetic phenomenon whereby vibrating a person’s muscle provides a false sense of movement.

Prosthetic technology has advanced significantly in recent years, but proprioception is one thing that many of these modern devices still cannot reproduce, Marasco says. And it’s clear that this is something that people find important, he adds, because many individuals with upper-limb amputations still prefer old-school body-powered hook prosthetics. Despite being low tech—the devices work using a bicycle brake–like cable system that’s powered by the body’s own movements—they provide an inherent sense of proprioception.

To restore this sense for amputees who use the more modern prosthetics, Marasco and his colleagues decided to create a device based on what’s known as the kinesthetic illusion: the strange phenomenon in which vibrating a person’s muscle gives her the false sense of movement. A buzz to the triceps will make you think your arm is flexing, while stimulating the biceps will make you feel that it’s extending (Exp Brain Res, 47:177–90, 1982). The best illustration of this effect is the so-called Pinocchio illusion: holding your nose while someone applies a vibrating device to your bicep will confuse your brain into thinking your nose is growing (Brain, 111:281–97, 1988). “Your brain doesn’t like conflict,” Marasco explains. So if it thinks “my arm’s moving and I’m holding onto my nose, that must mean my nose is extending.”

To test the device, the team applied vibrations to the reinnervated muscles on six amputee participants’ chests or upper arms and asked them to indicate how they felt their hands were moving. Each amputee reported feeling various hand, wrist, and elbow motions, or “percepts,” in their missing limbs. Kitts, who had met Marasco while taking part in the studies he was involved in at the institute in Chicago, was one of the subjects in the experiment. “The first time I felt the sense of movement was remarkable,” she says.

In total, the experimenters documented 22 different percepts from their participants. “It’s hard to get this sense reliably, so I was encouraged to see the capability of several different subjects to get a reasonable sense of hand position from this illusion,” says Dustin Tyler, a biomedical engineer at Case Western Reserve University who was not involved in the work. He adds that while this is a new, noninvasive approach to proprioception, he and others are also working on devices that restore this sense by stimulating nerves directly with implanted devices (Sci Rep, 8:9866, 2018).

Marasco and his colleagues then melded the vibration with the movement-controlled prostheses, so that when participants decided to move their artificial limbs, a vibrating stimulus was applied to the muscles to provide them with proprioceptive feedback. When the subjects conducted various movement-related tasks with this new system, their performance significantly improved (Sci Transl Med, 10:eaao6990, 2018).

The first time I felt the sense of movement was remarkable.

“This was an extremely thorough set of experiments,” says Marcia O’Malley, a biomedical engineer at Rice University who did not take part in that study. “I think it is really promising.”

Although the mechanisms behind the illusion largely remain a mystery, Marasco says, the vibrations may be activating specific muscle receptors that provide the body with a sense of movement. Interestingly, he and his colleagues have found that the “sweet spot” vibration frequency for movement perception is nearly identical in humans and rats—about 90 Hz (PLOS ONE, 12:e0188559, 2017).

For Kitts, a system that provides proprioceptive feedback means being able to use her prosthetic without constantly watching it—and feeling it instead. “It’s whole new level of having a real part of your body,” she says.

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