This illustration shows how thin a layer of sensors can be applied to the brain before surgery,
Courtesy of the Integrated Electronics and Biointerfaces Laboratory
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Courtesy of the Integrated Electronics and Biointerfaces Laboratory
Flexible foil studded with tiny sensors could make surgery safer for patients with brain tumors or severe epilepsy.
The experimental film, which looks like a Saran wrap, rests on the surface of the brain and detects the electrical activity of nerve cells beneath it. It is designed to help surgeons remove diseased tissue while maintaining important functions such as language and memory.
“It will help us do a better job,” says Dr. Ahmed Raslan, a neurosurgeon at Oregon Health and Science University who helped prepare the film.
The technology’s concept is similar 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 looking at the moon on a clear night,” Dayeh says, “then imagine (looking) through a telescope.”
In addition to aiding surgery, the film should provide researchers with a much clearer picture of the activity of neurons responsible for functions such as movement, speech, sensation and even thinking.
“We have such complex circuits in our brains,” says John Ngai, who directs the BRAIN initiative at the National Institutes of Health, which funded much of the film’s development. “This will help us better understand how they work.”
Mapping the diseased brain
The video aims to improve a process called functional brain mapping, which is often used when a person needs surgery to remove a brain tumor or tissue that is causing severe seizures.
During surgery, surgeons place a grid of sensors on the surface of an unconscious patient’s brain, taking care not to tear the delicate membrane. They then ask the patient to perform tasks such as counting or moving a finger.
Some tasks may be specific to a particular patient.
“If someone is a mathematician, we will give them a mathematical formula,” Raslan says. “If someone is a painter, we will give them a so-called visual cognition task.”
Sensors show which areas of the brain become active during each activity. However, the boundaries of these areas are usually irregular, says Raslan.
“It’s like a coastline,” he says, “it zigzags and curves.”
The accuracy of the brain map depends on the number of sensors used.
“The clinical grid we use today uses one registration point for every centimeter,” Raslan says. “The new grid uses at least 100 points.”
This is possible because each sensor in the new mesh is “a fraction of the diameter of a human hair,” Dayeh says. The mesh itself is connected to a plastic sheet so thin and flexible that it follows every contour of the brain’s surface.
From animals to people
The device works well for animals. In May, the FDA approved it for human testing.
Dayeh and Raslan, who have a financial interest in the device, say the team is already working on a wireless version that can be implanted for up to 30 days. This would enable people with severe epilepsy to be monitored for seizures at home rather than in 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 scientists to map the brain in more detail.
Fritz Liedtke of Oregon Health and Science University
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Fritz Liedtke of Oregon Health and Science University
Ultimately, scientists hope to use this diagnostic tool as a brain-computer interface for people who are unable to communicate or move.
This would allow them to “translate thoughts into action,” Dayeh says.
Scientists have already created this type of brain-computer interface using sensors implanted deep in the brain. However, a grid on the surface of the brain would be safer and could potentially detect the activity of many more neurons.
Tax money at work
Daye’s research is part of the federal BRAIN initiative, which was launched a decade ago to develop tools that reveal the inner workings of the human brain.
The new network is one tool, Ngai says. But it also promises to improve care for people with brain disorders.
“Ultimately, our goal was to develop better ways to treat people,” Ngai says, “and I think this is a big step for us toward achieving that goal.
Future progress may be slower. This year, Congress cut funding for the BRAIN initiative by approximately 40 percent.
Still, says Ngai, the new sensor grid and its wireless counterpart show how far the field has come.
Ten years ago, Ngai says, some of the country’s top electrical and computer engineers said such devices couldn’t work.
“Now you look,” he says, “and it’s done.”