The field of prosthetics has come a long way since its inception. Developments in nanotechnology have led to the production of artificial skin, allowing amputees to “feel” using their prosthetics. Surgical advances mean that prosthetic hands can be connected to our body’s nervous system. Now, a study in the journal Nature Biotechnology showcases a new, incredibly small brain implant that potentially could control an entire exoskeleton – via an interface – using the power of thought.
Unlike some modern artificial limb systems, which reattach previously severed or damaged nerves to the prosthetics, this interface is implanted directly into the brain during a single, short, low-risk operation. Just the size of a paperclip, this minimally-intrusive device sits within a blood vessel, and is capable of recording high-quality signals emitted from the brain’s motor cortex, the part of the brain responsible for coordinating movement.
This device was tested on live sheep for 190 days, as these animals have a motor cortex that has a comparable anatomy to a human brain. Over time, the implanted electrode recorded the cortex’s electrical signals, some of which were forcibly produced by electrically stimulating the sheep’s forelimbs. These recorded signals were compared to commercially available data obtained from electrode arrays implanted directly onto the brain surface via surgery.
The authors of the study conclude that their electrode records cortex signals comparable to the traditional types. Importantly, the implanted electrode did not appear to cause dangerous clotting within or damage the blood vessel it was inserted into. Remarkably, the quality of the recording improved over time, as the electrode became increasingly incorporated into the blood vessel.
This electrode is clearly able to register and record motor cortex signals in sheep – and the authors of this study have begun to speculate on what it could be used to achieve in humans. Co-principal investigator and biomedical engineer at the University of Melbourne, Dr. Nicholas Opie, said in a statement that his team is “hoping to achieve direct brain control of an exoskeleton for three people with paralysis” during the human trials, which are due to take place in 2017.
Could this new electrode be used to manipulate an exoskeleton? Ociacia/Shutterstock
“Currently, exoskeletons are controlled by manual manipulation of a joystick to switch between the various elements of walking – stand, start, stop, turn,” he adds. “[Our electrode] will be the first device that enables direct thought control of these devices.”
One of the problems that the U.S. military’s technological wing – the Defense Advanced Research Projects Agency (DARPA) – identified with this type of interface was the difficulty in getting high-resolution signals from a human brain. Indeed, the authors of this new study note that successful attempts at recording the detailed electrical activity of the brain over long periods of time, using implanted electrodes, have not been previously reported.
However, this new study points out that implanted electrodes that both record local neural tissue electrical signals, and electrically stimulate this tissue, are not new concepts – long-term implanted, artificial pacemaker and defibrillator devices already exist. Their new proof-of-concept device is the neurological equivalent of this, and appears to have made a significant advance in the ability to record signals – significantly, without involving risky open-brain surgery.
