Medical News
Neuroprosthetics gives hope to the paralysed and amputees
Science mimics sensory feedback in real time by stimulating nerve signals
SOURCE : COTESYS . ORG
Neuroprosthetics researchers in
America have successfully enabled a man with severe paralysis to communicate in sentences , translating signals from his brain to his vocal tract directly into words that then appear as text on a screen . Using a rapidly evolving science that blends neurology with engineering , the scientists are developing devices that can enhance the input or output of the human neural system .
In the study , Dr Edward Chang , a University of California neurosurgeon , surgically implanted a high-density electrode array over the patient ’ s speech motor cortex . After the participant ’ s full recovery , his team recorded 22 hours of neural activity over 48 sessions and several months . In each session , the patient attempted to say each word many times while the electrodes recorded brain signals from his speech cortex .
To translate the patterns of the recorded neural activity into specific intended words , Dr Chang ’ s team used artificial intelligence to distinguish subtle patterns in brain activity to detect speech attempts and identify which words he was trying to say .
“ To our knowledge , this is the first successful demonstration of direct decoding of full words from the brain activity of someone who is paralysed and cannot speak ,” said Dr Chang on publishing the study in the New England Journal of Medicine .
Neuroprosthetics researchers have also identified crucial techniques that go beyond speech and communication to restore sensation for amputees and help paralysed people walk again . In one study , a Swiss-led team created a leg neuroprosthesis that mimics sensory feedback in real time by stimulating nerves in the remaining limb .
This mimicking helps overcome a shortcoming in current leg prostheses in that they do not restore the sensation of touch in lower-leg amputees and can leave patients at higher risk of falls and poor mobility , as well as with the perception that the prosthesis is an external object instead of part of the body .
“ It ’ s very difficult for above-knee amputees to climb stairs quickly or cross obstacles when they ’ re wearing commercial prosthetics ,” Dr Stanisa Raspopovic of ETH Zurich , told Global Health Asia-Pacific . “ That ’ s why we developed a prosthetic leg to give them the level of feeling they need because a commercial prosthetic is not connected to the brain , it doesn ’ t feel like it ’ s part of the body .”
His team at the public Swiss university implanted tiny electrodes in the thigh nerves of three people , after which they were able to recognise when different spots on their prosthetic feet were touched and were better at climbing stairs and navigating obstacle courses . The trial participants also had greater ownership of their bodies and were less mentally occupied with the prosthesis , adding to a greater sense of freedom .
Other research from Switzerland has succeeded in helping a monkey walk again after its spinal cord was severed . Researchers at Ecole Polytechnique Federale de Lausanne developed a neuroprosthetic system , what they called a “ brain-spine interface ”, to bypass the injury and restore communication between the brain and the region of the spinal cord .
The interface bridges the spinal cord injury , in real-time and wirelessly , by decoding spiking activity from the brain ’ s motor cortex and relaying this information to a system of electrodes located over the surface of the lumbar spinal cord , a complex network of neurons that activates leg muscles to walk .
But the researchers say it may take a number of years before all the components of the intervention can be tested in people .
34 OCTOBER 2021 GlobalHealthAsiaPacific . com