Researchers demonstrate first human use of high-bandwidth wireless brain-computer interface

Brain-computer interfaces (BCIs) are an emerging assistive technology, allowing paralyzed people to type on computer screens or manipulate robotic prostheses just by thinking of moving their own body. For years, experimental BCIs used in clinical trials have required cables to connect the sensing network in the brain to computers that decode the signals and use them to drive external devices.

Now, for the first time, BrainGate clinical trial participants with quadriplegia have demonstrated the use of a wireless intracortical BCI with an external wireless transmitter. The system is able to transmit brain signals at single neuron resolution and with broadband fidelity without physically attaching the user to a decoding system. Traditional cables are replaced by a small transmitter about 2 inches in its largest dimension and weighing just over 1.5 ounces. The unit sits above a user’s head and connects to an array of electrodes in the motor cortex of the brain using the same port used by wired systems.

For a study published in IEEE Transactions on Biomedical Engineering, two clinical trial participants with paralysis used the BrainGate system with a wireless transmitter to point, click and type on a standard tablet. The study showed that the wireless system transmitted signals with virtually the same fidelity as wired systems, and participants achieved similar point-and-click accuracy and typing speeds.

“We have demonstrated that this wireless system is functionally equivalent to wired systems that have set the benchmark for BCI performance for years,” said John Simeral, assistant professor of engineering (research) at Brown University, member of the BrainGate. research consortium and lead author of the study. “The signals are recorded and transmitted with similar fidelity, which means that we can use the same decoding algorithms that we used with wired equipment. The only difference is that people no longer need to be physically attached to our equipment, which opens up new possibilities in terms of how the system can be used. “

The researchers say the study represents an early but important step towards a major goal of BCI research: a fully implantable intracortical system that helps restore independence in people who have lost the ability to move. Although wireless devices with lower bandwidth have been reported previously, this is the first device to transmit the full spectrum of signals recorded by an intracortical sensor. This high speed wireless signal enables clinical research and basic human neuroscience which are much more difficult to achieve with wired BCIs.

The new study has demonstrated some of these new possibilities. The trial participants – a 35-year-old man and a 63-year-old man, both paralyzed with spinal cord injuries – were able to use the system at home, as opposed to the lab where most of the research is taking place. BCI. Unimpeded by cables, participants were able to use the BCI continuously for up to 24 hours, giving researchers long-lasting data, even while participants were asleep.

“We want to understand how neural signals change over time,” said Leigh Hochberg, professor of engineering at Brown, a researcher at Brown’s Carney Institute for Brain Science and head of the BrainGate clinical trial. “With this system, we are able to examine brain activity at home over long periods of time in a way that was almost impossible before. This will help us to design decoding algorithms that allow transparent, intuitive and reliable communication restoration. and the mobility of the paralyzed. “

The device used in the study was first developed at Brown in the lab of Arto Nurmikko, a professor at Brown’s School of Engineering. Dubbed the Brown Wireless Device (BWD), it was designed to transmit high fidelity signals while consuming minimal power. In the current study, two devices used together recorded neural signals at 48 megabits per second from 200 electrodes with a battery life of over 36 hours.

While the BWD has been used successfully for several years in basic neuroscience research, further testing and regulatory clearance was required before using the system in the BrainGate trial. Nurmikko says the shift to human use marks a key moment in the development of BCI technology.

“I have the privilege of being part of a team that is pushing the boundaries of brain-machine interfaces for human use,” said Nurmikko. “It is important to note that the wireless technology described in our article has helped us gain crucial information for the way forward in the pursuit of the next generation of neurotechnologies, such as fully implanted high-density wireless electronic interfaces for the brain.

The new study marks another significant breakthrough from researchers at the BrainGate Consortium, an interdisciplinary group of researchers from Brown, Stanford, and Case Western Reserve universities, as well as Providence Veterans Affairs Medical Center and Massachusetts General Hospital. In 2012, the team published landmark research in which clinical trial participants were able, for the first time, to operate multidimensional robotic prostheses using a BCI. This work was followed by a constant stream of system improvements, as well as new clinical breakthroughs that allowed people to type on computers, use tablet apps, and even move their own paralyzed limbs.

“The evolution of intracortical BCIs from the need for a wire rope to the use of a miniature wireless transmitter is a major step towards the functional use of fully implanted high performance neural interfaces,” said Sharlene Flesher, co-author of the study, postdoctoral fellow at Stanford and is now a hardware engineer at Apple. “As the field moves towards reducing transmitted bandwidth while preserving the control precision of assistive devices, this study may be one of the few that captures the full extent of cortical signals for extended periods of time. time, including during practical use of BCI.

New wireless technology is already paying unexpected dividends, researchers say. Because participants can use the wireless device in their homes without an on-site technician to maintain the wired connection, the BrainGate team was able to continue their work during the COVID-19 pandemic.

“In March 2020, it became clear that we would not be able to visit the homes of our research participants,” said Hochberg, who is also an intensive care neurologist at Massachusetts General Hospital and director of the VA Rehabilitation Research and Development Center for Neurorestoration and Neurotechnology. “But by teaching caregivers how to wirelessly connect, a trial participant was able to use BCI without our team members being physically present. So not only were we able to continue our research, but this technology allowed us to continue the bandwidth and fidelity that we had before. “

Simeral noted that “several companies have entered the BCI arena wonderfully, and some have already demonstrated human use of low-bandwidth wireless systems, including some that are fully implemented. In this report, we are delighted that we used high bandwidth. wireless system that advances the scientific and clinical capabilities of future systems. “

Brown has a licensing agreement with Blackrock Microsystems to make the device available to neuroscientists around the world. The BrainGate team plans to continue using the device in ongoing clinical trials.