The project aims to develop a wireless neural prosthetic system made up of thousands of implantable microdevices that could deepen understanding of the brain and lead to new medical therapies.
With a grant of up to $19 million from the Defense Advanced Research Projects Agency (DARPA), Brown University will lead a collaboration to develop a fully implantable wireless brain interface system able to record and stimulate neural activity with unprecedented detail and precision.
The international team of engineers, neuroscientists and physicians involved in the project envisions an approach to neural interfaces that is unlike any available today. They aim to create a "cortical intranet" of tens of thousands of wireless micro-devices — each about the size of a grain of table salt — that can be safely implanted onto or into the cerebral cortex, the outer layer of the brain. The implants, dubbed "neurograins," will operate independently, interfacing with the brain at the level of a single neuron. The activity of the devices will be coordinated wirelessly by a central communications hub in the form of a thin electronic patch worn on the skin or implanted beneath it.
The system will be designed to have both "read-out" and "write-in" capabilities. It will be able to record neural activity, helping to deepen scientists' understanding of how the brain processes stimuli from the outside world. It will also have the capability to stimulate neural activity through tiny electrical pulses, a function researchers hope to eventually use in human clinical research aimed at restoring brain function lost to injury or disease.
"What we're developing is essentially a micro-scale wireless network in the brain enabling us to communicate directly with neurons on a scale that hasn't previously been possible," said Arto Nurmikko, L. Herbert Ballou University Professor of Engineering at Brown and the project's principal investigator. "The understanding of the brain we can get from such a system will hopefully lead to new therapeutic strategies involving neural stimulation of the brain, which we can implement with this new neurotechnology."
The research team will include researchers from Brown, IMEC (a Belgian microtechnology institute), Massachusetts General Hospital, Stanford University, the University of California, Berkeley, the University of California, San Diego, the mobile telecommunications firm Qualcomm, and the Wyss Center for Bio and Neuroengineering in Geneva. The funding, to be distributed over four years, comes from DARPA's new Neural Engineering System Design (NESD) program, which is aimed at developing new devices "able to provide advanced signal resolution and data-transfer bandwidth between the brain and electronics."
At Brown, the work will build on decades of research in neuroengineering and brain-computer interfaces, computational neuroscience and clinical therapeutics through the Brown Institute for Brain Science, the University's Warren Alpert Medical School and its School of Engineering.
"Brown has a tradition of innovative multidisciplinary research in brain science, especially with projects that have the potential to transform lives through technology-assisted repair of neurological injuries," said Jill Pipher, vice president for research at Brown. "This new grant enables a group of outstanding Brown researchers to develop leading-edge technology and solve new computational problems in a quest to understand human brain functionality at a totally new scale."
Four Brown faculty members will serve as co-investigators on the project. Leigh Hochberg is a professor of engineering and one of the leaders of the BrainGate consortium, which develops and tests brain-computer interfaces through ongoing human clinical trials. David Borton is an assistant professor of engineering who previously worked with Nurmikko to develop the first fully implantable brain sensor that could transmit information wirelessly. Larry Larson, Sorensen Family Dean of Engineering, is a leader in semiconductor microwave technology and wireless communication. Wilson Truccolo, an assistant professor of neuroscience, has developed unique theoretical and computational approaches to decoding and encoding neural signals from cortical microcircuits. Each will lend their expertise to the project alongside the team's experts from leading institutions in the U.S. and abroad, with additional collaboration with companies such as software developer Intel Nervana.
"This is an ambitious project that will require a convergence of expertise from across disciplines," Larson said. "We work very hard to make the School of Engineering the kind of place where these kinds of projects thrive, and we're very much looking forward to the work ahead of us."
New challenges, new technologies
The project will involve many daunting technical challenges, Nurmikko said, which include completing development of the tiny neurograin sensors and coordinating their activity.
"We need to make the neurograins small enough to be minimally invasive but with extraordinary technical sophistication, which will require state-of-the-art microscale semiconductor technology." Nurmikko said. "Additionally, we have the challenge of developing the wireless external hub that can process the signals generated by large populations of spatially distributed neurograins at the same time. This is probably the hardest endeavor in my career."
Then there's the challenge of dealing with all of the data the system produces. Current state-of-the-art brain-computer interfaces sample the activity of 100 or so neurons. For this project, the team wants to start at 1,000 neurons and build from there up to 100,000.
"When you increase the number of neurons tenfold, you increase the amount of data you need to manage by much more than that because the brain operates through nested and interconnected circuits," Nurmikko said. "So this becomes an enormous big data problem for which we'll need to develop new computational neuroscience tools."
The team will first apply new technologies to the sensory and auditory function in mammals. The level of detail expected from the neurograin system, the researchers say, should yield an entirely new level of understanding of sensory processes in the brain.
"We aim to be able to read out from the brain how it processes, for example, the difference between touching a smooth, soft surface and a rough, hard one and then apply microscale electrical stimulation directly to the brain to create proxies of such sensation," Nurmikko said. "Similarly, we aim to advance our understanding of how the brain processes and makes sense of the many complex sounds we listen to every day, which guide our vocal communication in a conversation and stimulate the brain to directly experience such sounds."
The Brown-led team is one of six research teams to be awarded grants from DARPA under the NESD program, which was launched last year. Other awarded projects will be led by researchers at Columbia University, the Foundation for Vision and Understanding, John B. Pierce Laboratory, Paradromics and the University of California, Berkeley.
- Kevin Stacey