Imagine if a matchstick-sized brain implant could circumvent damaged spinal cords and help paralyzed people become mobile – powered by their own thoughts. The futuristic technology, which involves a tiny device containing a tangle of electrodes, has been shown to successfully record neural activity in sheep. Next up, it will be tested on up to five volunteers possibly as soon as next September, according to Nick Opie, a biomedical engineer at the University of Melbourne and the Australian project’s chief technical officer.
The so-called stentrode is designed to relay thoughts wirelessly to an external robotic device, such as an exoskeleton or prosthetic limb, to enable patient-directed brain control over movement and locomotion. It’s part of a growing field of robotics for human augmentation, which the McKinsey Global Institute predicted in 2013 could assist more than 50 million people with impaired mobility in the developed world, and yield economic benefits of as much as $2 trillion a year by 2025. “Our aim is to return mobility, independence and communication to some of these men and women,” Opie said. “We are using the device to extract information that has already been generated by the brain and to bypass the damaged nerves.”
Other research groups have similar ideas. Neuralink Corp, the startup co-founded by billionaire Elon Musk, is developing ultra-high bandwidth brain-machine interfaces to connect humans and computers. And Facebook Inc’s research unit Building 8 is working to make it possible for people to type using signals from their brains. The stentrode is made of electrodes on an expandable mesh stent that’s inserted into a blood vessel atop the motor cortex, the part of the brain that controls movement, via a thin catheter inserted in the groin. Once in position, the catheter is withdrawn, enabling the stentrode to expand against the vessel wall, creating a hollow, cigar-shaped wire tube that records brain activity.
The installation procedure is virtually identical to that used by neuroradiologists to remove blood clots from stroke patients, and can be done in about 30-40 minutes, Opie said. Made from a nickel and titanium alloy, the stent is flexible with high tensile strength, enabling it to be maneuvered through through blood vessels without invasive surgery. “The avenue that we have chosen avoids any open-brain surgery,” Opie said. “A lot of other technologies require removal of the skull, and that’s risky. We are avoiding that by going through the veins.”
While the approach is less invasive than brain surgery, its potential to tap neural signals may be limited by its placement, since it can only be implanted in blood vessels large enough to support the stent, said Newton Howard, professor of computational neurosciences and neurosurgery at the University of Oxford in England. The stent dilates to 4 millimeters. “A successful technology should be more versatile in that it can be implanted anywhere in the brain, not just along preexisting vasculature,” Howard said in an email.
There is also at least a theoretical risk of the device causing blockages and, therefore, increasing the risk of stroke, he said, adding that this may see the device deemed inappropriate or “contraindicated” for individuals predisposed to the condition. “Rather than this overtaking present technology, I believe this will become a staple of the upcoming generation of brain-computer interface technology,” said Howard, who is also chairman of the Brain Sciences Foundation and studies the development of functional brain and neuron interfacing. “The stentrode is fundamentally different from other technology.”
The technology was developed by researchers at the University of Melbourne, the Royal Melbourne Hospital, and the Florey Institute of Neuroscience and Mental Health, with funding from the US Defense Advanced Research Projects Agency in Arlington, Virginia, and the Australian National Health and Medical Research Council. There are an estimated 100,000 American veterans with a spinal cord injury or disease, according to the Paralyzed Veterans of America, a congressionally chartered veterans service organization. The technology “has the potential to transform the lives of our wounded warriors and others with disabilities,” President Barack Obama said in an April 2016 video on YouTube that discussed the project.
Synchron Inc, a company Opie and colleagues formed to develop the stentrode, said in April that it raised A$10 million ($7.6 million) to complete a so-called Series A round of financing. Once safety in humans has been established, Synchron will look to enroll about 30 people in a global trial possibly in 2019, Opie said, adding that it’s too early to estimate how much the device will cost. “The company was started up to make sure that, once it passed the first-in-human trials, it would have a very clear way to market and be made available to people who need it,” he said.
A subsequent phase of development will investigate the potential for the stentrode to be used for other brain-related disorders, including epilepsy and Parkinson’s disease. “For any brain technology to succeed, it’s really all about the data: do they show efficacy, with a minimum of side effects?” said Edward Boyden, a professor of biological engineering and brain and cognitive sciences at the Massachusetts Institute of Technology’s McGovern Institute for Brain Research in Boston. “That’s the burden that any new brain technology faces.”