February 2021

The Nation Reviewed

Brain waves

By Nenad Macesic

Brain–computer interfaces promise communication capabilities for those paralysed by neurological dysfunction

The effects of a stroke are doubly tragic. The immediate impact can leave people with a devastating loss of faculties and independence, often due to paralysis and loss of speech. The second tragedy is that until recently modern medicine was largely incapable of restoring these people’s lives. The Oxford Handbook of Clinical Medicine, a pocket guide carried by generations of medical students, sets the scene for the budding physician in the introduction to the neurology chapter: “But the best thing you can ever offer is the unwritten contract that, come what may, you will be there, available, often ineffectual …”

The majority of strokes are due to clots blocking arteries in the brain, depriving brain tissue of the oxygen and nutrients that arrive on these transport superhighways. Unless something is done quickly, this leads to the irreversible death of brain tissue. Fortunately, the past decade has seen the emergence of promising new treatments that aim to break up or mechanically retrieve the clot before permanent damage occurs. To do this, interventional neurologists such as Associate Professor Tom Oxley insert a large wire into a patient’s artery, which then traces its way to the brain to “suck” the clot up. Once the blockage is relieved the effects can be profound, almost magical, with patients recovering the use of limbs that seconds ago hung lifeless at their sides.

From an early age, Oxley was fascinated by the brain and how it forms our experience of consciousness. As a junior doctor, he sought to look beyond the disability wrought by neurological illness to find solutions. A pivotal moment occurred on the night shift during his residency at Melbourne’s Alfred Hospital, when he read an article on an early brain–computer interface called a Utah array. This device allows scientists to pick up electrical signals directly from the brain but it requires surgical implantation, making it difficult to use outside of a research setting. Oxley linked this burgeoning field of brain–computer interfaces with the latest developments in interventional neurology. If we were now able to insert wires to retrieve a clot from the brain, could this not also serve as a path for introducing devices that interact with the brain? This possibility could bring about not only new ways of monitoring what is happening within the brain but also a means of transmitting signals from the brain to the outside world, signals that could control computers or other machines.

This gets to the heart of what for many patients is the most debilitating aspect of living with neurological conditions: the loss of communication. Oxley gives the example of Stephen Hawking, who suffered from motor neurone disease. Despite losing the ability to speak in 1985, Hawking was able to continue communicating his ideas until his death in 2018. To write his final book, he used a communication aid that laboriously scrolled through a keypad, with Hawking selecting letters using movements of his facial muscles. Although this is an incredible achievement, it is easy to imagine how a brain–computer interface could have facilitated that process, perhaps allowing Hawking to write not one book in his last years but several. The journey to create such a device has occupied the past decade of Oxley’s life.

In 2011, as a junior doctor, Oxley travelled to the United States and sent emails to leading neuroscientists to discuss his idea of using blood vessels to implant brain–computer interfaces. Unsurprisingly, the response rate was in the single digits, but among them was Professor Geoffrey Ling, from the Defense Advanced Research Projects Agency. DARPA is the US government agency responsible for bringing to fruition high-risk but potentially transformative technologies that may have military applications. While these projects are largely moonshots, the agency was central to the development of many now-omnipresent technologies such as the internet and GPS. At that time, many US combat veterans were returning from the conflicts in Iraq and Afghanistan having lost limbs in blast injuries. Professor Ling was spearheading an effort to develop a prosthetic arm for amputees. Despite the exquisite engineering feats in making this complex machine, the accurate control of the arm by the user remained a key problem, leading to Ling’s interest in Oxley’s idea. After initial meetings with Ling, Oxley returned to Australia with a verbal agreement that DARPA would provide US$1 million of funding if Oxley could bring together a viable team to pursue his project.

A device’s ability to interface directly with the human brain seems like the stuff of science fiction. Indeed, the writer Iain M. Banks developed the concept of “neural lace” – permanently implanted brain–computer interfaces – in his Culture series of novels, while neural implants that connect people’s brains directly to cyberspace are a central feature of William Gibson’s seminal cyberpunk novel Neuromancer. However, the foundations for this technology had already been pioneered in Australia with the development of the cochlear implant at the University of Melbourne. Oxley was able to access that expertise and build a formidable team that included scientists who had worked on the cochlear implant and subsequently moved on to the bionic eye. With the DARPA funding unlocked, Oxley made the development of a “smart stent” the focus of his doctoral studies.

As opposed to stents used in cardiology, which act to simply open up a blood vessel, this device would be implanted in a vein close enough to brain tissue to pick up electrical signals. The device has to reach its destination and open up enough to stay in place but not so much that it causes damage to the surrounding brain tissue. In addition, the brain is an inhospitable place for foreign materials, with dangerous risks of corrosion. Even if all of these steps occur successfully, the device must pick up electrical signals from the brain, then transform them into meaningful outputs that can perform complex functions such as controlling a prosthetic limb. This requires significant achievements in material engineering combined with machine learning algorithms, which must correctly classify the electrical signals into interpretable messages.

Despite these challenges, Oxley and his team were able to make prototypes using discarded neurological stents, onto which they painstakingly overlayed circuitry by hand. This allowed the research to progress to animal trials, which involved implanting the devices in sheep. Improbably, Oxley and his colleagues used weekend drives to the countryside as scouting trips to find sheep with skull sizes suitable for experiments. While Oxley’s doctoral research garnered several accolades and demonstrated that the device worked in sheep, it now needed to get to human patients. This led him back to the US, where he pursued a neurointerventional fellowship, and his PhD project rapidly evolved into a start-up called Synchron. DARPA had been interested in helping combat veterans with traumatic injuries, but the technology could potentially help any patient that had a neurological loss of muscle function, ranging from patients suffering from stroke to those with motor neurone disease, multiple sclerosis or brain tumours.

This vast potential has led Oxley’s group to conduct a clinical trial aiming to enrol 15 Australian patients, with preliminary results published for two patients with motor neurone disease. The patients can now control a cursor with a combination of their eyes and mind. The cursor is controlled by minute movements of their eye muscles, while the brain–computer interface gives them the ability to click and zoom using electrical signals generated by their thoughts. These tasks sound simple, but they represent a major step towards restoring communication, thus providing a bridge to loved ones and the world at large.

The momentous nature of this achievement isn’t lost on Oxley. “Patients with paralysis have had independence taken away from them. When it is given back, their world expands,” he says. “It’s a little bit like when you first get your driver’s licence and are able to drive, when previously you couldn’t. The world suddenly just opens up to you.” Oxley expects that the device will reach clinical use within five years. As recognition for his pioneering scientific endeavours, Oxley was one of the Victorian nominees for the 2021 Australian of the Year.

Lately the world of brain–computer interfaces has drawn increasing attention. In 2016, as Oxley’s group was moving to human trials, Elon Musk founded Neuralink, which also aims to bring brain–computer interfaces to humans. A lot of hype stems from the possibility that these devices could not just restore lost functions but perhaps augment memory or analytical processes, leading to speculation about “augmented” or even “virtual” humanity.

When asked about the future of brain–computer interfaces, Oxley identifies communication as being at the core: “It’s one thing to connect a brain to a computer, but imagine connecting minds directly. Right now, we rely on language and non-verbal communication, but this could be a form of direct communication. You could feel how someone else is feeling instantaneously, without saying anything to them. You could sense someone’s decision-making before they’ve made a decision.”

After a year of COVID-imposed isolation, where communication is a revolving struggle of emails, phone calls and video conferences, this prospect feels both exhilarating and terrifying.

Nenad Macesic

Nenad Macesic is an infectious diseases physician and researcher based in Melbourne.

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