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This new brain-mapping device could make neurosurgery safer

 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
This illustration shows how the thin film of sensors could be applied to the brain before surgery,

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.

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
/
Fritz Liedtke / Oregon Health & Science University
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.

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.”

Copyright 2024 NPR

Jon Hamilton is a correspondent for NPR's Science Desk. Currently he focuses on neuroscience and health risks.