A mechanical arm conveys the sensation of being paralyzed

The paralyzed American found touch in an artificial hand

Oleg Lischuk, N+1

American scientists have developed a neurointerface that allowed a completely paralyzed person to touch objects with a prosthesis. The results of the work are published in the journal Science Translational Medicine (Flesher et al., Intracortical microstimulation of human somatosensory cortex).

Most experimental interfaces that provide sensitivity to the prosthetic arm are connected to peripheral nerves. During training, their stimulation leads to the formation of new neuronal connections in the brain, which translate signals from the sensors of the prosthesis into tactile sensations. Such sensations, as a rule, are far from natural and resemble tingling or tingling. In addition, such interfaces require undisturbed communication of peripheral nerves with the cerebral cortex and are not suitable for patients with spinal cord injuries or neurodegenerative diseases.

Employees of the Universities of Pittsburgh and Chicago have created a tactile interface that connects directly to the area of the cerebral cortex responsible for tactile sensitivity in the hand. To test the system, they invited 28-year-old Nathan Copeland, who in 2004 had an accident and suffered an injury to the cervical spine and damage to the thoracic spinal cord, which led to paralysis of the forearms and lower extremities.

Preparation for testing the neurointerface.
Here and below are UPMC drawings.

The scientists identified the required area of Copeland's somatosensory cortex using MRI and magnetoencephalography, and then implanted four sensors with microelectrodes into it. For several months, they applied weak electrical impulses to various combinations of electrodes, registering the sensations they cause and their localization in the virtual palm. Then the interface was connected to sensors on a robotic prosthetic arm created at Johns Hopkins University.

Implantable microelectrodes

After a period of adaptation and training, Copeland found the ability to correctly recognize touches to individual fingers in almost 100 percent of cases. According to him, sometimes the sensations resemble the action of an electric current or pressure, but in most cases he feels touches and presses close to natural. Temperature sensitivity has not yet been restored.

"The most important result of the study was that micro-electrical stimulation of the sensory cortex can provide natural sensations, and not a simple tingling. Such stimulation is safe, and the patient's sensations have been stable for several months," explained one of the authors of the work, Andrew Schwartz, in a press release In a First, Pitt-UPMC Team Help Paralyzed Man Feel Again Through a Mind-Controlled Robotic Arm.

At the next stage of the work, the scientists plan to combine the tactile system with a previously developed neural interface that controls the movements of the prosthesis. The ultimate goal is to create a device that is as close in function as possible to a real hand, however, according to the researchers, this will require a lot of work.

Many scientific and engineering teams are engaged in the development of bionic prostheses with various functions and purposes. So, there are already experimental prostheses that provide fine sensitivity of the finger, warning about a burn by an electric shock, as well as a neurointerface that allows you to control individual fingers of the prosthesis. An artificial hand has been created at Case Western University, which is capable of performing various subtle actions. Open Bionics is developing a bionic arm from the Deus Ex game, and their competitors Mobius Bionics have promised to start mass production of a Luke Skywalker prosthesis by the end of 2016.

Portal "Eternal youth" http://vechnayamolodost.ru  17.10.2016