A new, ultrathin, ultraflexible implant loaded with sensors can
record the electrical storm that erupts in the brain during a seizure
with nearly 50-fold greater resolution than was previously possible. The
level of detail could revolutionize epilepsy treatment by allowing for
less invasive procedures to detect and treat seizures. It could also
lead to a deeper understanding of brain function and result in
brain-computer interfaces with unprecedented capacity.
Brain map: An ultrathin array of electrodes, shown at top being
inserted into the brain of a cat, allows for data acquisition far
greater than ever before possible. At bottom, the electrode array is so
flexible that it can fold around even the slimmest objects, allowing for
easy insertion and good coverage of uneven surfaces.
For epilepsy patients who don't respond to medication, neurologists
will often try to map where in the brain the seizure originated so that
region can be surgically removed. The doctor removes a section of skull
and places a bulky sensor array on the surface of the patient's frontal
cortex.
"These clinical devices haven't changed much since the '50s or '60s," says Brian Litt,
an epilepsy specialist and bioengineer at the University of
Pennsylvania and one of the scientists who led the new research. Because
the device has to accommodate wires for each electrode, it only has
space for fewer than 100 electrodes and gives a poor resolution picture
of the electrical activity. "It's like trying to understand what's going
on in a crowd in Manhattan with a single microphone suspended from a
helicopter," Litt says.
Out of control: An epileptic seizure in a cat, as measured by the
new electrode-dense implant, shows a never-before-seen spiral wave of
electrical activity.
Current technology has stalled out at a sensor array with about eight
sensors per square centimeter; the new array—built in collaboration
with John Rogers,
a professor of materials science and engineering at the University of
Illinois Urbana-Champaign—can fit 360 sensors in the same amount of
space. To create a small device so densely packed with sensors, Rogers
integrated electronics and silicon transistors into the array itself,
drastically reducing the amount of wiring.
"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. "This new
technique could be the key to understanding functional networks in the
brain, and could even be the key to treating and potentially curing some
diseases."
In their first test of the device, on a cat with epilepsy, Litt, Rogers, and graduate student Jonathan Viventi
(now an assistant professor studying translational neuroengineering at
New York University), saw something striking: a storm of activity that
looked like a self-propagating spiral wave. The pattern, only apparent
with incredibly high-resolution recording, is remarkably similar to one
seen in cardiac muscle during a life-threatening condition called
ventricular fibrillation.
Rather than large sections of the brain being responsible for
seizures, something Litt says has traditionally been thought to occur,
it appears to instead stem from multiple clusters of very small areas,
or "microdomains," in the cortex. The research was published online last
week in Nature Neuroscience.
"This is absolutely terrific. I was astounded by the technical accomplishment, and the very strong and important results," says Gerwin Schalk,
a brain-computer interface researcher at the Wadsworth Center in
Albany, New York. Schalk was not involved in the research. "It will be
of tremendous value for basic neuroscience and for translational
research." Schalk notes that if the technology proves itself in humans,
it could open up substantial opportunities for everything from
diagnostics to brain-computer interface devices.
The device could also enable less-invasive testing and treatment.
Rather than cutting open a large section of skull to place a monitoring
device, Litt says, the new implant could allow surgeons to drill just a
small hole through which to slip the slim, rolled-up sensor array, and
unfurl it onto the brain's surface once it's inside. And instead of
removing areas of brain the size of a golf ball, it might be possible to
just remove the microdomains and leave the rest of the cortex intact.
The current version of the device is one square centimeter; for human
use, researchers need to expand it to about eight square centimeters. A
startup called MC10 will work on making it larger and production-ready.
Litt and Rogers are now working to create an implant with stimulators
embedded next to the sensors. If they can build a device that not only
detects the onset of a seizure but can just as quickly provide
electrical stimulation to quash it, the research could have great
clinical impact. "This isn't just a research tool. It has a clearly
defined mode of use in the clinical setting," Rogers says. "This is a
piece of biointegrated electronics that is unmatched in its
functionality, and the proof is in the pudding."
By Lauren Gravitz
From Technology Review
2 comments:
Its superb to see that medical history has made such advancements.This recent invention of ultrathin chips will really help scientists to study brain with more detail and an attempt to overcome the brain diseases.
I just want to say that this is very good approach and this helps to all the medical field related persons.
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