New window system allows for long-term studies of brain activity

Date:
March 11, 2022
Source:
Georgia Institute of Technology
Summary:
A researcher has developed a tiny window that allows investigators
to get clearer, long-term imaging of the brain's visual network.



FULL STORY ========================================================================== Bilal Haider is studying how multiple areas of the brain work together
for visual perception. This could help researchers understand if neural activity "traffic jams" underlie all kinds of visual impairments: from
running a red light when visual attention is elsewhere, to shedding
light on the autism- affected brain.


==========================================================================
To do this kind of work, researchers need a reliable "map" of all
the visual brain areas with specific coordinates for each unique
brain. Drawing the map requires monitoring and recording data from an
active, working brain, which usually means creating a window in the
skull to watch blood flow activity.

Haider's team has developed a better approach -- a new kind of window
that's more stable and allows for longer-term studies. The assistant
professor in the Wallace H. Coulter Department of Biomedical Engineering
at Georgia Tech and Emory University explains how in a paper published in February in Scientific Reports,an open access forum of Nature publishing.

To get a clear image of the brain's visual network, Haider's lab uses an established technique called blood flow imaging, which tracks oxygen in
the blood, measuring the active and inactive areas of a mouse brain while
the animal views visual stimuli. To capture a strong blood flow signal, researchers typically create a cranial window by thinning the skull
or removing a piece of it altogether. These procedures can diminish
stability in the awake, pulsing brain -- detrimental conditions for
delicate electrophysiological measurements made in the same visual areas
after imaging.

"Standard windows give really good pictures of the vasculature,"
Haider said.

"But the downside is, if you're working with an animal learning how to
perform a sophisticated task that requires weeks of training, and you
want to do neural recordings from the brain later, that area has been compromised if the skull is missing or thinned out." The team's new
cranial window system allows for high-quality blood flow imaging and
stable electrical recordings for weeks or even months. The secret is a
surgical glue called Vetbond -- which contains cyanoacrylate, the same
compound that's in Krazy Glue -- and a tiny glass window.

Basically, a thin layer of the glue is applied to the skull with a
micropipette and a curved glass coverslip is placed on top of that. The cyanoacrylate creates a "transparent skull" effect. Haider's team
developed the new window system and then vetted the accuracy of the
resulting visual brain maps.

"Sometimes the simplest things work. The glue creates a barrier allowing
all of the normal physiological processes underneath to carry on,
but leaving the bone transparent," Haider said. "It's like putting a
protector on your smartphone.

The protector is over the glass surface, but everything underneath stays crystal clear and functioning." Haider's approach will help his team accomplish their larger goals -- to measure the activity of neurons
in the brain's visual pathways and understand how neural traffic jams
diminish our visual attention, and how these processes may contribute
to visual impairments in people with autism. It's work that's getting a
boost, thanks to recent support of the Simons Foundation Autism Research Initiative.

Haider said proper study of brain function requires repeatable
measurements of neural activity, so he has made the new window system
publicly available.

"We think this will be useful tool for other researchers," he said. "We
made the code, all the hardware, all the specs of the system, everything, totally public so that other people can try it themselves. We designed
this to use in our study of the visual brain, but it can potentially be
used to study other brain areas in a way that allows researchers to do long-term experiments while keeping the brain stable and healthy."

========================================================================== Story Source: Materials provided by Georgia_Institute_of_Technology. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Armel Nsiangani, Joseph Del Rosario, Alan C. Yeh, Donghoon Shin,
Shea
Wells, Tidhar Lev-Ari, Brice Williams, Bilal Haider. Optimizing
intact skull intrinsic signal imaging for subsequent targeted
electrophysiology across mouse visual cortex. Scientific Reports,
2022; 12 (1) DOI: 10.1038/s41598-022-05932-2 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220311115319.htm

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