And with this our researchers could listen in to signals between neurons and learn exactly what signals are sent between neurons to cause neuroplasticity to work.
http://www.rdmag.com/news/2015/03/carbon-nanotube-fibers-make-superior-links-brain?
Carbon nanotube fibers invented at Rice Univ. may provide the best way to communicate directly with the brain.
The fibers have proven superior to metal electrodes for deep brain
stimulation and
to read signals from a neuronal network. Because they
provide a two-way connection, they show promise for treating patients
with neurological disorders while monitoring the real-time response of
neural circuits in areas that control movement, mood and bodily
functions.
New experiments at Rice demonstrated the biocompatible fibers are
ideal candidates for small, safe electrodes that interact with the
brain’s neuronal system, according to the researchers. They could
replace much larger electrodes currently used in devices for deep brain
stimulation therapies in Parkinson’s disease patients.
They may also advance technologies to restore sensory or motor
functions and brain-machine interfaces as well as deep brain stimulation
therapies for other neurological disorders, including dystonia and
depression, the researchers wrote.
The paper appeared online in
ACS Nano.
The fibers created by the Rice lab of chemist and chemical engineer
Matteo Pasquali consist of bundles of long nanotubes originally intended
for aerospace applications where strength, weight and conductivity are
paramount.
The individual nanotubes measure only a few nanometers across,
but when millions are bundled in a process called wet spinning, they
become thread-like fibers about a quarter the width of a human hair.
“We developed these fibers as high-strength, high-conductivity
materials,” Pasquali said. “Yet, once we had them in our hand, we
realized that they had an unexpected property: They are really soft,
much like a thread of silk. Their unique combination of strength,
conductivity and softness makes them ideal for interfacing with the
electrical function of the human body.”
The simultaneous arrival in 2012 of Caleb Kemere, a Rice assistant
professor who brought expertise in animal models of Parkinson’s disease,
and lead author Flavia Vitale, a research scientist in Pasquali’s lab
with degrees in chemical and biomedical engineering, prompted the
investigation.
“The brain is basically the consistency of pudding and doesn’t
interact well with stiff metal electrodes,” Kemere said. “The dream is
to have electrodes with the same consistency, and that’s why we’re
really excited about these flexible carbon nanotube fibers and their
long-term biocompatibility.”
Weeks-long tests on cells and then in rats with Parkinson’s symptoms
proved the fibers are stable and as efficient as commercial platinum
electrodes at only a fraction of the size. The soft fibers caused little
inflammation, which helped maintain strong electrical connections to
neurons by preventing the body’s defenses from scarring and
encapsulating the site of the injury.
The highly conductive carbon nanotube fibers also show much more
favorable impedance—the quality of the electrical connection—than
state-of-the-art metal electrodes, making for better contact at lower
voltages over long periods, Kemere said.
The working end of the fiber is the exposed tip, which is about the
width of a neuron. The rest is encased with a three-micron layer of a
flexible, biocompatible polymer with excellent insulating properties.
The challenge is in placing the tips. “That’s really just a matter of
having a brain atlas, and during the experiment adjusting the
electrodes very delicately and putting them into the right place,” said
Kemere, whose lab studies ways to connect signal-processing systems and
the brain’s memory and cognitive centers.
Doctors who implant deep brain stimulation devices start with a
recording probe able to “listen” to neurons that emit characteristic
signals depending on their functions, Kemere said. Once a surgeon finds
the right spot, the probe is removed and the stimulating electrode
gently inserted. Rice carbon nanotube fibers that send and receive
signals would simplify implantation, Vitale said.
The fibers could lead to self-regulating therapeutic devices for
Parkinson’s and other patients. Current devices include an implant that
sends electrical signals to the brain to calm the tremors that afflict
Parkinson’s patients.
“But our technology enables the ability to record while stimulating,”
Vitale said. “Current electrodes can only stimulate tissue. They’re too
big to detect any spiking activity, so basically the clinical devices
send continuous pulses regardless of the response of the brain.”
Kemere foresees a closed-loop system that can read neuronal signals
and adapt stimulation therapy in real time. He anticipates building a
device with many electrodes that can be addressed individually to gain
fine control over stimulation and monitoring from a small, implantable
device.
“Interestingly, conductivity is not the most important electrical
property of the nanotube fibers,” Pasquali said. “These fibers are
intrinsically porous and extremely stable, which are both great
advantages over metal electrodes for sensing electrochemical signals and
maintaining performance over long periods of time.”
Source:
Rice Univ.
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