This is very much a successful proof of concept. It does mean that
direct electronic access to specific neuron paths is feasible. What
this really means is that prosthetic brain control is plausible and
the real bionic man will likely step forth.
We always thought as much, but the lab work is now catching up.
As mentioned, it will be a decade before much of this is into the
market but it is now known science and technology.
A better brain
implant: Slim electrode cozies up to single neurons
by Staff Writers
Ann Arbor MI (SPX) Nov 15, 2012
An artist's rendering of individual neurons. A new electrode developed at the University of Michigan can focus on the electrical signals of just one neuron. It may help researchers understand how electrical signals move through neural networks in the brain. Because this electrode is so small and unobtrusive, it may be able to stay in the brain for long periods without upsetting the immune system, perhaps picking up signals to send to prosthetic limbs. Image credit: Takashi Kozai
A thin, flexible
electrode developed at the University of Michigan is 10 times
smaller than the nearest competition and could make long-term
measurements of neural activity practical at last.
This kind of
technology could eventually be used to send signals to prosthetic
limbs, overcoming inflammation larger electrodes cause that damages
both the brain and the electrodes.
The main problem that
neurons have with electrodes is that they make terrible neighbors. In
addition to being enormous compared to the neurons, they are stiff
and tend to rub nearby cells the wrong way. The resident immune cells
spot the foreigner and attack, inflaming the brain tissue and
blocking communication between the electrode and the cells.
The new electrode
developed by the teams of Daryl Kipke, a professor of biomedical
engineering, Joerg Lahann, a professor of chemical engineering, and
Nicholas Kotov, the Joseph B. and Florence V. Cejka Professor of
Engineering, is unobtrusive and even friendly in comparison. It is
a thread of highly conductive carbon fiber, coated in plastic to
block out signals from other neurons. The conductive gel pad at the
end cozies up to soft cell membranes, and that close connection means
the signals from brain cells come in much clearer.
"It's a huge step
forward," Kotov said. "This electrode is about seven
microns in diameter, or 0.007 millimeters, and its closest competitor
is about 25 to 100 microns."
The gel even speaks
the cell's language, he said. Electrical impulses travel through the
brain by movements of ions, or atoms with electric charges, and the
signals move through the gel in the same way. On the other side,
the carbon fiber responds to the ions by moving electrons,
effectively translating the brain's signal into the language of
electronic devices.
To demonstrate how
well the electrode listens in on real neurons, Kipke's team implanted
it into the brains of rats. The electrode's narrow profile allows it
to focus on just one neuron, and the team saw this in the sharp
electrical signals coming through the fiber.
They weren't getting
a muddle of multiple neurons in conversation. In addition to picking
up specific signals to send to prosthetics, listening to single
neurons could help tease out many of the brain's big puzzles.
"How neurons are
communicating with each other? What are the pathways for information
processing in the brain? These are the questions that can be answered
in the future with this kind of technique," Kotov said.
"Because these
devices are so small, we can combine them with emerging optical
techniques to visually observe what the cells are doing in the brain
while listening to their electrical signals," said Takashi
Kozai, who led the project as a student in Kipke's lab and has since
earned his Ph.D. "This will unlock new understanding of how the
brain works on the cellular and network level."
Kipke stressed that
the electrode that the team tested is not a clinical trial-ready
device, but it shows that efforts to shrink electrodes toward the
size of brain cells are paying off.
"The results
strongly suggest that creating feasible electrode arrays at these
small dimensions is a viable path forward for making longer-lasting
devices," he said.
In order to listen to
a neuron for long, or help people control a prosthetic as they do a
natural limb, the electrodes need to be able to survive for years in
the brain without doing significant damage. With only six weeks of
testing, the team couldn't say for sure how the electrode would fare
in the long term, but the results were promising.
"Typically, we
saw a peak in immune response at two weeks, then by three weeks it
subsided, and by six weeks it had already stabilized," Kotov
said. "That stabilization is the important observation."
The rat's neurons and
immune system got used to the electrodes, suggesting that the
electronic invaders might be able to stay for the long term.
While we won't see
bionic arms or Iron Man-style suits on the market next year, Kipke is
optimistic that prosthetic devices could start linking up with the
brain in a decade or so.
"The surrounding
work of developing very fine robotic control and clinical training
protocols-that work is progressing along its own trajectory,"
Kipke said.
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