This illustration shows how a thin film of sensors is attached to the brain before surgery. Courtesy of the Institute of Integrated Electronics and Biointerfaces. Hide caption
Toggle caption Provided by Institute of Integrated Electronics and Biointerfaces
A flexible film packed with tiny sensors could make surgery safer for patients with brain tumours or severe epilepsy.
The experimental film, similar to Saran Wrap, is applied to the surface of the brain to detect electrical activity from nerve cells underneath, and is designed to help surgeons remove diseased tissue while preserving vital functions such as language and memory.
“This will enable us to do a better job,” said Dr. Ahmed Raslan, a neurosurgeon at Oregon Health & Science University who helped develop the film.
The technology is similar in concept to sensor grids already used in brain surgery, but with 100 times higher resolution, says Shadi Daye, an engineer at the University of California, San Diego, who is leading the effort.
“Imagine you're looking at the moon on a clear night,” Daye says, “and [looking through] “telescope”
Not only will the film be an aid to surgery, it should also give researchers a clearer picture of the neural activity that governs functions such as movement, speech, sensation and even thought.
“Our brains are complex circuits,” said John Ngai, director of the National Institutes of Health's BRAIN Initiative, which funded the film's development. “This film will help us better understand how they work.”
Mapping the diseased brain
The film aims to improve a process called functional brain mapping, which is often used when surgery is needed to remove brain tumours or tissue causing severe epileptic seizures.
During the operation, surgeons place a grid of sensors on the surface of a conscious patient's brain – careful not to rupture delicate membranes – and then instruct the patient to perform actions such as counting or moving their fingers.
Some tasks may be specific to certain patients.
“If someone is a mathematician, we give them a mathematical formula,” Ruslan says, “and if someone is a painter, we give them what we call a visual perception task.”
The sensors show which brain regions are active during each activity, but the boundaries between these regions tend to be irregular, Ruslan says.
“It's like a coastline,” he says. “It zigzags.”
The accuracy of the brain map depends on the number of sensors used.
“The clinical grid we use today uses one recording point every centimeter,” says Ruslan. “In the new grid, we will use at least 100 points.”
This is possible because each sensor on the new grid is “just a fraction of the diameter of a human hair,” Daye says, and the grid itself is glued to a plastic film that is thin and flexible enough to follow any contours of the brain's surface.
From animals to humans
The device worked well in animals, and in May the FDA approved it for human testing.
Daeh and Raslan, who have a financial interest in the device, say their team is already working on developing a wireless version that could be implanted for up to 30 days, allowing people with severe epilepsy to monitor their seizures at home rather than in a hospital.
Dr. Ahmed Raslan, a neurosurgeon at Oregon Health & 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 Hide caption
Toggle caption Fritz Liedtke / Oregon Health & Science University
The researchers ultimately hope to use this diagnostic tool as a brain-computer interface for people who cannot communicate or move.
This will allow them to “put their ideas into action,” Daye said.
Scientists are already developing this kind of brain-computer interface using sensors implanted deep inside the brain, but placing a grid on the brain's surface could be safer and detect many more neurons' activity.
Utilizing taxes
Day's research is part of the federal government's BRAIN initiative, launched a decade ago to develop tools to reveal the inner workings of the human brain.
Ngai says the new grid is one tool, but it also holds the promise of improving care for people with brain injuries.
“The ultimate goal was to develop better ways to treat humans,” Ngai said, “and I think this study is a big step toward that goal.”
Progress going forward may come more slowly: This year, Congress cut funding for the BRAIN Initiative by about 40 percent.
Still, the new sensor grid and its wireless counterpart show how far the field has come, Ngai says.
Ngai said 10 years ago, some of the country's top electrical engineers and computer scientists said such a device would never work.
“Look now,” he says, “and it's running.”
