Flexible, foldable implant maps brain activity during seizures

Clinical devices used to map where in the brain a seizure originated haven’t changed much since the 1950s.

Scientist have now designed an ultrathin implant carrying a dense array of sensors to record the electrical activities of the brain during a seizure.

The level of detail captured by the ultraflexible device (pictured) – capable of conforming to the brain’s shape – has a nearly 50-fold greater resolution than was ever possible, potentially revolutionizing epilepsy treatment. Technology Review reports.

Doctors trying to map where a seizure originates must usually remove a section of skull to place a bulky sensor array on the surface of the patient's frontal cortex. That way, the problem region can be surgically removed. Having to accommodate wires for each electrode, the devices usually only has space for fewer than 100 electrodes.

Current sensor arrays have about 8 sensors per square centimeter. "It's like trying to understand what's going on in a crowd in Manhattan with a single microphone suspended from a helicopter," says study researcher Brian Litt of the University of Pennsylvania.

So he, John Rogers of the University of Illinois at Urbana-Champaign and colleagues, built a new array that fits 360 sensors in that same one square centimeter amount of space. They reduced the amount of wiring drastically by integrating electronics and silicon transistors into the array itself.

"This is more like an array of 360 microphones, lowered closer to the surface and recorded from much smaller regions: a couple of people at the street corner, a couple by the mailbox," Litt says.

And it’s less invasive. Rather than cutting open a large section of the skull, surgeons only have to drill a small hole to slip in the rolled-up sensor array – which unfurls onto the brain’s surface once inside.

After testing their device on a cat with epilepsy (pictured right), they discovered that the storm of activity looked more like a self-propagating spiral wave: rather than large sections of the brain being responsible for seizures, it appears to stem from multiple clusters of very small areas. Instead of having to remove large areas of the brain, neurosurgeons might only need to remove those small areas.

For human use, they’re working on expanding the device to about 8 square centimeters. A startup called MC10 will work on making it larger and production-ready.

The study was published in Nature Neuroscience last week. From MIT Technology Review.

Images: Nature Neuroscience

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