Brain Interfaces: What is Implanted Embodiment?
The word “embodiment” can conjure up an array of thoughts and images. For a patent, embodiment describes the use, production, expression or practice of an invention. In the world of art, embodiment drives the meaning of the perception of emotion. Both are true in their own context. What do you imagine when you think of brain interface embodiment?
This takes me back two decades to my first Neural Interfaces meeting on the campus of the National Institutes of Health in Bethesda, Maryland. As part of a panel of neurotechnology users, I and other panelists were taking questions from an audience of scientific investigators. Dr. Joe Schulman of the Alfred E. Mann Foundation posed a question like this:
“If we cut open your skull, implanted an array into your motor cortex, wirelessly connected it to a prosthetic, and then you can move by thought, would you get it?”
My gut reaction took over and I blurted out this response:
“You lost me at cut open your skull.”
The imagery of opening and exposing my brain to the world seemed foreign two decades ago. Today, over 160,000 people have taken that step to have a deep brain stimulator implanted into their brains. Even more people are taking the options to implant interfaces into the brain for various conditions. Over these last two decades, brain implants have advanced in safety and efficacy. In this second of our brain interfaces series, we will focus on implanted devices with an overview of the applications of today. Our next installment will review external devices.
Brain Interfaces for Treatment of Conditions
One of the most prominent implanted brain interface technologies used today is deep brain stimulation (DBS). There are systems currently available for the treatment of Parkinson’s disease, essential tremor and dystonia. Devices with regulatory approval for clinical use include those from well known companies such as Abbott, Boston Scientific and Medtronic. There are other innovative vendors entering this space as well, such as Newronika, Aleva Therapeutics, and Bioinduction.
Implanted brain interfaces are also approved for other specific conditions. Neuropace, for instance, has the RNS system that provides stimulation and sensing capabilities to treat refractory epilepsy. They are now exploring the use of their device for idiopathic generalized epilepsy as well as Lennox-Gastaut Syndrome. Another company has been developing DBS for the treatment of Alzheimer’s disease, Functional Neuromodulation. Their device currently has CE Mark in Europe and is under investigation in the U.S. with an on-going human clinical trial. Another start-up company are working to commercialize implanted brain interfaces for expanded indications. Nia Therapeutics is applying their investigational device for memory restoration after traumatic brain injury or as a result of Alzheimer’s disease.
For some time now, implanted electrodes have been used in the field of diagnostics and monitoring of the brain state. External electroencephalography (EEG) has been used to monitor the brain state of people living with epilepsy to pinpoint the area of the brain that causes the seizures. In some cases, external EEG cannot be precise enough to make a determination for the source in the brain. In these cases, other measures need to be taken. This is where an evolving area of diagnostics in brain interfaces has introduced a new generation of electrocortiography (ECoG). These electrodes are used to map the brain activity with precision. They are used intraoperatively (during surgery) to confirm the location and recordings of the electrical activity within the brain. Companies like Dixi Medical and Ad-Tech have been supplying electrodes for this use. More recently, the emergence of electrodes with “soft” properties that are conducive to the squishy brain tissue have been coming onto the market. Many of these electrodes may be placed in the brain up to 30 days rather than only a few days. Companies like Neuraura Biotech, Conscious Labs, INBRAIN Neuroelectronics, NeuroOne, WISE, and Neurosoft Bioelectronics are leaders in this innovation. The use of neural dust is another potential platform. The company developing that technology, iota Biosciences, was acquired by Astellas Pharmaceuticals in 2020.
Implanted Brain Interface with Computers or Machines
What has been attracting the media attention is the development of implanted brain interfaces to interact with computers, external devices or peripheral machines. Some neurotech companies are developing the components like electrode arrays and processors. Companies such as BlackRock Microsystems, Precision Neuroscience, Ripple, and CorTec are the quiet innovators for components of brain interface systems. The components play an important role in the development of full systems but it is the application of those systems that are catching the public attention. Companies like Paradromics, Neuralink and Synchron are breaking new ground to bring brain interfaces with new applications. At the moment, implanted brain interfaces remain within the medical model, meaning the treatment or application is for a specific medical condition such as paralysis or locked-in syndrome. They could emerge into non-medical applications but that is for a different section of this series. At this point, the applications discussed here have been, are or will soon be under investigation in clinical trials.
Direct Brain Computer or Machine Interfaces Applications
The tools to capture minute brain signals, translate them using complex algothrims and use them to interact with external devices is the target for much research in this area. Teams lead by Drs. Philip Kennedy, John Donoghue, Miguel Nicolelis, Krishna Shenoy, Jonathan Wolpaw, Eddie Chang, and Andrew Schwartz, are peppered within the research community.
A New Means of Communication
Locked-in syndrome is a rare condition that can be characterized as paralysis of most muscles except for those that control eye movement. For people living with locked-in syndrome, being able to communicate is a ticket out of jail. People living with this condition are cognitively aware and functioning, but lack the ability to respond. Conversations become one word answers of ‘yes’ and ‘no’. Dr. Kennedy and his team implanted a neurotrophic-cone electrode to create a BCI system to restore speech. The electrode sensed activity in the speech epicenter of the brain and translated those signals with about an 80% accuracy. The first human implant was in 1998. Nearly twenty-five years later, Drs. Eddie Chang and Karunesh Ganguly, applied the next generation of speech prosthesis. In the BRAVO (Brain-Computer Interface Restoration of Arm and Voice) study, their first participant who has paralysis in his limbs and vocal tract received an implanted electrode in the speech area of the brain. After several sessions of training, he was able to think about a 50 word vocabulary. The implant translated his thoughts into spoken words through a computer. This thought-to-speech translation gave this user a new voice to the world. There is also a research team in Ottawa, Canada exploring the use of implanted brain interfaces as a potential “Neuro Communicator.” The progress might feel slow but the technical advancements could usher in a new means of communication.
Ditching the Keyboard, Mouse or Joystick
Brain Computer Interface or BCI earned its name as the first human use case of thought translated to an external computer. Much of the early pre-clinical work consisted of brain implants for non-human primates playing video games connected to a computer. Those studies laid the foundation for this technology to evolve into human applications. Early in the 21st century, a man with quadriplegia was the first to receive a BCI in the form of an implanted device. After calibrating the signals from the implant to an algorithmic processor, the signals were translated to computer inputs. In a person without paralysis, the thought of typing words are translated from motor potentials in the brain that travel through the nervous system to the fingers that then provide input into a keyword of a computer. With the BCI, that process is more direct. Back to the man living with quadriplegia, he would think about typing the words, the implant captured those potentials, and then they are translated directly to the computer. This same process can work for a keyboard, a mouse, a tablet and even a joystick for gaming. Since that first implant, there have been several research labs testing these applications.
Controlling Robotics
Going beyond interaction with a computer, what about turning action potentials into, well, action. Could a brain interface be used for navigating a wheelchair or controlling a prosthetic or robotic limb? The development in this area is moving fast and changing the way we think about control inputs. Making that important step from animal studies to applications for people, Drs. Donoghue and Hochberg have lead a team using an implanted electrode array into the motor cortex of people with high levels of paralysis due to spinal cord injury, ALS and brain stem stroke to control a computer screen as well as a robotic arm. For these systems, the sensing electrode is place over the motor cortex of the brain. The electrode captures the brain signals and translates those signals to movements. The first users of this system were able to move a robotic arm simply through thoughts. Teams at the University of Pittsburgh, California Institute of Technology, Johns Hopkins University, Singapore National Neuroscience Institute, University of Chicago and others, have been able to achieve similar results. The research team at the Grenoble University Hospital in France is taking implanted brain interfaces to control robotics one step further, literally. They are exploring the use of an implanted brain electrode for the use of controlling a motorized exoskeleton. The early results demonstrate that two people living with paralysis were able to control an exoskeleton with up to eight-degrees of freedom.
Combining Brain Interfaces and Body Movement
There are two areas of exciting research for the application of electrical stimulation and brain signals. One is in the area of cortical stimulation for stroke survivors. Here, stimulation is applied to the damaged sections of the brain to excite neural activity to ‘retrain’ the brain neurons in a phenomenon known as neural plasticity. Implanted brain interfaces were used for the rehabilitation of limb function following a stroke. The first human studies were conducted in the early 2000s in multiple centers with a commercial sponsor, Northstar Neuroscience. For various reasons, the trials were discontinued but the prospects for coupling brain stimulation with rehabilitation were highlighted.
Today, investigators are exploring the use of deep brain stimulation technologies and applying them for stroke rehabilitation. The early studies are underway at the Cleveland Clinic in Ohio with the first DBS implant in 2016. The trial is still on-going but the preliminary results are showing promise to regain functional movement by coupling of brain stimulation with physical rehabilitation. Two commercial entities are exploring the use for stroke recovery. Enspire DBS Therapy is conducting a clinical trial for combining rehabilitation and DBS for movement recovery following stroke. Epic Neuro is investigating the use of an implanted EEG and stimulation system for targeted physical therapy. We will revisit the topic of brain stimulation with rehabilitation in the discussion of non-invasive brain interfaces.
The other promising use of implanted brain interfaces for body movement is the use of FES applications to move paralyzed limbs. The research team at Battelle in partnership with The Ohio State University has been able to connect an implanted brain interface with a surface electrical stimulation system. This research team used a brain electrode placed on the motor cortex of a person with quadriplegia and connected that brain electrode to a sleeve. The sleeve has embedded surface stimulation electrodes that are specially placed to deliver electrical stimulation to muscles in the arm to allow for movement of the fingers, hand and wrist. This connection between the systems allows the user to think about hand movement, then the brain implant captures that signal, decodes it and sends it to the controller for the sleeve to activate the electrical stimulation in the sleeve. The result is a thought provoked hand movement.
Another research team at Case Western Reserve University took this same concept but connected the brain implant to an implanted electrical stimulation (FES) system for hand function. The implanted FES system consists of small electrodes surgically placed on the muscles in the hands and arms. The user can then control the implanted FES system for hand function simply through thought. If you are curious to meet these pioneering users, we will introduce you to them later in this brain interface series.
The potential of implanted brain interfaces to be translated into functional and meaningful applications are just starting to open the door of possibilities.
Look for the next installment of this Brain Interfaces series featuring the world of external or non-invasive devices.
More information about the neurotech devices for various neurological conditions and other network resources may be found on the Neurotech Network website. Follow us on Twitter or LinkedIn.
