Neuroscientists are learning new things about how the brain functions
thanks to a newly created neural probe with an unparalleled number of
micro-LEDs and recording sites combined on the same neural device. The
hectoSTAR probe's 128 LEDs and 256 recording electrodes enable
neuroscientists to monitor interactions among various brain areas.
Mihály Vöröslakos, a neurologist at New York University and the study's
primary author, stated, "With the hectoSTAR probe, we could address several
problems that we were not able to answer before." "Being the first to test
these gadgets affords a rare opportunity since we have technology that no
one else has."
With additional channels, neuroscientists can record not only a larger
portion of the brain but also the relationships between various regions,
which may provide crucial information for treating neurological
illnesses.
The hectoSTAR probe can image an area that extends from the cortex on the
outside of a rodent's brain all the way down to the hippocampus in the deep
brain. It is equipped with four 30-m thick silicon micro-needle shanks and
can record from a region of roughly 1 mm2 (1.3 mm x 0.9 mm) up to 6 mm deep
within the brain.
It was developed by University of Michigan researchers for two years before
it was successfully tested for the first time in real-world
circumstances.
A live mouse's CA3 area of the hippocampus was the location of the
hectoSTAR probe. The recording electrodes recorded the neural response as
light streamed through one or more LEDs. The researchers found that the
light had an effect on the neurons in the CA1 area next to it in addition to
the cells next to them in the CA3 region. More over half a millimeter, or
600 microns, separates the CA3 and CA1 areas.
According to Vöröslakos, "using this technology, we may disturb the
neuronal system in a highly exact spatial and temporal manner." The
hectoSTAR gadget and the tiny LED probe in general are fantastic tools for
these research.
It takes time to advance scientific research, as well as frequently a lot
of teamwork and collaboration. Vöröslakos spent two years working in Prof.
Euisik Yoon's lab at the University of Michigan as a Kavli scholar to make
sure the new technology could answer very specific scientific questions.
Vöröslakos was already familiar with earlier versions of the brain probe
created by Yoon's team there.
Yoon's team published the first-ever neural probe in 2015 that can record
activity from many neurons and activate the activity of the neurons with a
resolution that is almost single cellular. These probes have 32 recording
electrodes and 12 LEDs. By eliminating the significant amount of noise that
LED stimulation had added to the recorded neural signal, Yoon's team in
2020—led by former doctoral student Kanghwan Kim (MSE PHD EE '15,
'20)—introduced a more useful microLED probe that enables high-quality
neural signal recording during LED stimulation.
Yoon stated, "That effort paved the road to scaling it up. "Numerous
engineering difficulties had to be solved, but the end product has allowed
neuroscientists to better comprehend the global interconnectedness of the
brain. This brand-new chip has us quite interested."
With an area of 8 by 11 micrometers, the new LEDs have nearly half the
surface area of the previous generation. The hectoSTAR team's chief
researcher, Kanghwan Kim, applied theory to produce enough light output to
activate the neurons.
When it came to making things smaller, nothing was trivial, according to
Kim.
Last but not least, Yoon remarked that raising the number of optical
stimulation locations to 128 was a bit of a nightmare. His team created an
open-source multi-channel LED controller system to separately regulate the
light emitted to each LED and then process the incoming data from the
recording electrodes in order to address the control issue.
Yoon explained, "We can carefully select which LEDs are lighted as well as
the intensity of the light, which has the capacity to activate only a few
neurons nearby the LED, and then record how the signal is travelling to
other areas of the brain."
It takes time to double the number of electrodes and LEDs by an order of
magnitude. I did had faith that it would work after spending so much time in
the cleanroom, said Kim. "Watching those little LEDs come to life was
amazing."
"Without it, we would have to insert several probes into the brain to
obtain the same data. We were still constrained by the animal's carrying
capacity, "Vöröslakos stated.
Vöröslakos is doing more research based on the hectoSTAR electrode's
findings and has already requested the devices' upcoming iterations.
In response, Yoon has directed his current research group to develop two
crucial improvements to the hectoSTAR: flexible probes and a significantly
smaller headstage board. The rat would be able to wander about without
restriction and live a long time while having its brain stimulated and
recorded thanks to these advancements.
Yoon's lab has previously hosted researchers from other institutions who
wanted to learn how to insert his nerve probes and gather data.
