Medical Design Briefs - July 2021 - 24

Neural Implant Monitors Multiple Brain Areas at Once,
Provides New Neuroscience Insights
Diverse patterns of twoway
communication occur
between two brain
regions.
UC San Diego
San Diego, CA
How do different parts of the brain
communicate with each other during
learning and memory formation? A new
study by researchers at the University of
California San Diego takes a first step at
answering this fundamental neuroscience
question.
The study was made possible by developing
a neural implant that monitors the
activity of different parts of the brain at
the same time, from the surface to deep
structures - a first in the field. Using
this new technology, the researchers
show that diverse patterns of two-way
communication occur between two brain
regions known to play a role in learning
and memory formation - the hippocampus
and the cerebral cortex. The
researchers also show that these different
patterns of communication are tied to
events called sharp-wave ripples, which
occur in the hippocampus during sleep
and rest. The researchers published their
findings in Nature Neuroscience.
" This technology has been developed
particularly for studying interactions
and communications between different
brain regions simultaneously, " says cocorresponding
author Duygu Kuzum, a
professor of electrical and computer
engineering at the UC San Diego Jacobs
School of Engineering. " Our neural
implant is versatile; it can be applied to
any area of the brain and can enable
study of other cortical and subcortical
brain regions, not just the hippocampus
and cerebral cortex. "
" Little is known about how various
brain regions work together to generate
cognition and behavior, " says Takaki
Komiyama, a professor of neurobiology
and neurosciences at UC San Diego
School of Medicine and Division of
Biological Sciences, who is the study's
other co-corresponding author. " In contrast
to
the traditional approach of
studying one brain area at a time, the
new technology introduced in this study
24
Intro
Cov
200 µm
e
f
d
50 µm
5 µm
SEM images of the neural implant's microelectrode array. (Credit: Nature Neuroscience)
will begin to allow us to learn how the
brain as a whole works to control behaviors
and how the process might be compromised
in neurological disorders. "
The neural implant is made up of a
thin, transparent, flexible polymer strip
fabricated with an array of micron-sized
gold electrodes, onto which platinum
nanoparticles have been deposited.
Each electrode is connected by a
microns-thin wire to a custom-printed
circuit board. Kuzum's lab developed
the implant. They worked with Komi -
yama's lab to perform brain imaging
studies in transgenic mice.
■ Engineering a Multi-Use Neural
Probe
What makes this neural implant unique
is that it can be used to monitor activity in
multiple brain regions at the same time. It
can record electrical signals from single
neurons deep inside the brain, like in the
hippocampus, while imaging large areas
like the cerebral cortex.
" Our probe enables us to combine
these modalities in the same experiment
seamlessly. This cannot be done with
current technologies, " says Xin Liu, an
electrical and computer engineering
PhD student in Kuzum's lab. Liu is a cofirst
author of the study along with Chi
Ren, a recent UC San Diego biological
www.medicaldesignbriefs.com
ToC
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A
sciences PhD graduate who is now a
postdoctoral researcher in Komiyama's
lab, and Yichen Lu, an electrical and
computer engineering PhD student in
Kuzum's lab.
Several design features make multiregion
monitoring possible. One is that
this probe is flexible. When it is inserted
deep into the brain to monitor a region
like the hippocampus, the part that
sticks out of the brain can be bent down
and make room for a microscope to be
lowered close to the surface to do imaging
of the cerebral cortex at the same
time. Conventional neural probes are
rigid, so they get in the microscope's
way; as a result, they cannot be used to
monitor deep brain structures while
imaging the brain's surface. And even
though the UC San Diego team's neural
probe is soft and flexible, it is engineered
to withstand buckling under
pressure during insertion.
Another important feature is that this
probe is transparent, so it gives the
microscope a clear field of view. It also
does not generate any shadows or additional
noise during imaging.
■ Exploring Fundamental
Neuroscience Questions
The motivation for this study was getting
to the root of how different cogniMedical
Design Briefs, July 2021
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Medical Design Briefs - July 2021

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