This new brain-mapping device could make neurosurgery safer
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This illustration shows how the thin film of sensors could be applied to the brain before surgery.Courtesy of the Integrated Electronics and Biointerfaces Laboratory -
Dr. Ahmed Raslan, a neurosurgeon at Oregon Health and Science University who helped develop the high-tech brain sensor grid, says the device will allow researchers to map the brain in greater detail.Fritz Liedtke / Oregon Health & Science University
A flexible film bristling with tiny sensors could make surgery safer for patients with a brain tumor or severe epilepsy.
The experimental film, which looks like Saran wrap, rests on the brain’s surface and detects the electrical activity of nerve cells below. It’s designed to help surgeons remove diseased tissue while preserving important functions like language and memory.
“This will enable us to do a better job,” says Dr. Ahmed Raslan, a neurosurgeon at Oregon Health and Science University who helped develop the film.
The technology is similar in concept to sensor grids already used in brain surgery. But the resolution is 100 times higher, says Shadi Dayeh, an engineer at the University of California, San Diego, who is leading the development effort.
“Imagine that you’re looking on a clear night at the moon,” Dayeh says, “then imagine [looking through] a telescope.”
In addition to aiding surgery, the film should offer researchers a much clearer view of the neural activity responsible for functions including movement, speech, sensation, and even thought.
“We have these complex circuits in our brains,” says John Ngai, who directs the BRAIN Initiative at the National Institutes of Health, which has funded much of the film’s development. “This will give us a better understanding of how they work.”
Mapping an ailing brain
The film is intended to improve a process called functional brain mapping, which is often used when a person needs surgery to remove a brain tumor or tissue causing severe epileptic seizures.
During an operation, surgeons place a grid of sensors on the surface of an awake patient’s brain, taking care not to tear the delicate film. Then they ask the patient to do tasks, like counting or moving a finger.
Some of the tasks may be specific to a particular patient.
“If somebody is a mathematician, we’ll give them a math formula,” Raslan says. “If somebody is a painter, we’ll give them what’s called a visual cognition task.”
The sensors show which brain areas become active during each activity. But the borders of these areas tend to be irregular, Raslan says.
“It’s like a shoreline,” he says, “it zigzags and it curves around.”
The accuracy of a brain map depends on the number of sensors used.
“The clinical grid we use now uses one point of recording every one centimeter,” Raslan says. “The new grid uses at least 100 points.”
That’s possible because each sensor on the new grid is “a fraction of the diameter of the human hair,” Dayeh says. And the grid itself is bonded to a plastic film so thin and flexible that it conforms to every contour of the brain’s surface.
From animals to humans
The device works well in animals. And in May, the FDA approved it for testing in people.
Dayeh and Raslan, who both hold a financial interest in the device, say the team is already working on a wireless version that could be implanted for up to 30 days. That would allow people with severe epilepsy to be monitored for seizures at home instead of in the hospital.
Ultimately, the researchers hope to use this diagnostic tool as a brain-computer interface for people who are unable to communicate or move.
That would allow them to “transduce their thoughts into actions,” Dayeh says.
Scientists have already created this sort of brain computer interface using sensors implanted deep in the brain. But a grid on the brain’s surface would be safer, and could potentially detect the activity of many more neurons.
Tax dollars at work
Daye’s research is part of the federal BRAIN Initiative, which was launched a decade ago to develop tools that would reveal the inner workings of the human brain.
The new grid is one of the tools, Ngai says. But it also promises to improve care for people with brain disorders.
“Ultimately, the goal was to develop better ways of treating human beings,” Ngai says, “and I think this gives us a pretty big stride toward that goal.
Future strides may come more slowly. This year, Congress cut BRAIN Initiative funding by about 40 percent.
Even so, Ngai says, the new sensor grid and its wireless counterpart show just how far the field has come.
A decade ago, Ngai says, some of the nation’s top electrical engineers and computer scientists said there was no way devices like these would work.
“You look now,” he says, “and it’s being done.”
Transcript
SACHA PFEIFFER, HOST:
Neurosurgeons often rely on custom maps of a patient's brain to avoid damaging critical areas. Most of those maps are still pretty crude, but as NPR's Jon Hamilton reports, new technology is making them much more precise.
JON HAMILTON, BYLINE: Surgery for a brain tumor or severe epilepsy can affect a person's language, movement, even memory. So before operating, Dr. Ahmed Raslan of Oregon Health and Science University asks which activities are most important to a patient.
AHMED RASLAN: If somebody wants to preserve playing the violin, we'll let them do so if somebody is a mathematician, will give them a math formula. If somebody is a painter, we give them what's called visual cognition task.
HAMILTON: Raslan says the key is identifying the brain area needed for a particular task, then marking it with an imaginary line.
RASLAN: It's really more like a shoreline. It zigzags, and it curves around.
HAMILTON: To map out this shoreline, surgeons often use a grid of sensors placed directly on the surface of a patient's brain. But the accuracy of this approach is limited by the number of sensors. So Raslan has been working with scientists at Massachusetts General Hospital and the University of California, San Diego. They've developed a new grid that crams many more sensors into a small area.
RASLAN: The clinical grid, the current one we use now, uses one point of recording every 1 centimeter. The new grid uses at least a hundred points of recording per square centimeter.
HAMILTON: The engineer behind this high-resolution device is Shadi Dayeh of UCSD. He says it's a startling improvement.
SHADI DAYEH: Imagine that you're looking in a clear night at the moon with traditional clinical electrodes. You wouldn't be able to see details. But then imagine holding a telescope, and then you start to be able to see better features.
HAMILTON: Dayeh says the new grid looks like a small square of saran wrap. It's transparent and so thin and flexible that it clings to every contour of the brain surface.
DAYEH: We have very tiny sensors that are a fraction of the diameter of the human hair.
HAMILTON: The device has worked well in animals, and in May, the FDA approved it for testing in people. Dayeh, who, along with Raslan, co-founded a company to market the new grid, says the team's next goal is to perfect a wireless version that would allow epilepsy patients to be monitored at home.
DAYEH: The third stage is to take patients who are unable to communicate with outer world or unable to move their limbs and use this technology to transduce their thoughts into actions.
HAMILTON: By generating speech on a computer or moving an artificial limb. This has already been done using electrodes implanted deep in the brain, but placing them on the surface is safer and gathers information from a greater number of neurons. Dayeh's research is part of the federal BRAIN Initiative, launched a decade ago to develop technologies that would reveal the inner workings of the human brain. John Ngai of the National Institutes of Health directs the effort.
JOHN NGAI: We have these complex circuits in our brains that are actually underlying our conversation right now, and the ability to look at the activity among these circuits with greater resolution will give us a better understanding of how all these processes work.
HAMILTON: Ngai says the new grid also promises to improve treatment of patients with epilepsy or brain tumors.
NGAI: Ultimately, the goal was to develop better ways of treating human beings, and I think this gives us a pretty good stride toward that goal.
HAMILTON: Future strides may take a bit longer, though. Congress cut this year's funding for the BRAIN Initiative by about 40%. Even so, Ngai says the new sensor grid and its wireless counterpart show just how far the field has come in the past decade.
NGAI: I remember sitting in a room with a group of some of the best electro engineers, computer scientists. and they said, well, geez, you know, even if you could do it, we wouldn't be able to get the data out. And you look at it now, and it's being done.
HAMILTON: Thanks to technology that didn't exist just a few years ago. Jon Hamilton, NPR News. Transcript provided by NPR, Copyright NPR.
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