Time-lapse images as the living brain responds to experiences

Date:
April 11, 2022
Source:
University of New Mexico Health Sciences Center
Summary:
Researchers use manganese-enhanced magnetic resonance imaging to
capture time-lapse images of the living brain.



FULL STORY ========================================================================== Magnetic resonance imaging (MRI) has transformed the field of neuroscience
over the past 40 years, enabling scientists to create clear snapshots
of living brain structures and even detect functional changes associated
with certain activities.


========================================================================== Unlike X-rays or CT scans, MRI does not rely on beams of
radiation. Instead, powerful magnetic fields and radio waves are used
to temporarily align the hydrogen atoms in the body's water molecules,
meaning it can create a clear picture of soft tissues, like the brain.

But a newer technology developed by UNM neuroscientist Elaine Bearer,
MD, PhD, and collaborators at California Institute of Technology and
the University of Southern California takes MRI one step further.

In a paper published in the journal NMR in Biomedicine, they report on
the use of manganese, a trace mineral found throughout the body, as a
contrast agent with MRI that enables a "time-lapse" series of images
revealing the brain's response to specific experiences.

"This report emphasizes the power of manganese-based contrast to study
dynamic transitions throughout the brain," said Bearer, a professor in the
UNM Department of Pathology. "The brain is not a static thing. This MRI technique images the slow consequences of an experience over time. It's enabling us to peer more deeply into the amazing complexity of thinking
and feeling." In manganese-enhanced MRI (MEMRI), small amounts of
manganese enter neurons via the same cellular pathway as calcium, which
plays a key role in brain signaling. As manganese ions move through the
neuron they highlight the cell's activities, highlighting the projections
via which it communicates with adjacent neurons.



========================================================================== "This exciting emergent methodology captures the brain's function
during normal behavior, which otherwise cannot be known at this scale,"
said Taylor Uselman, a PhD student in Bearer's lab who co-authored the
paper. Christopher Medina, MD, a UNM School of Medicine graduate, was
also a co-author.

"Our publication also provides critical insight into safety considerations
for the use of the contrast agent," Uselman said. "We give a number of
examples of how MEMRI reveals the development of the hearing system,
as well as Down syndrome, Alzheimer's disease and anxiety disorders."
Standard MRI scans have great diagnostic value for detecting tumors or
vascular abnormalities in the brain, and they can reveal that changes
in certain brain structures are associated with specific behaviors,
such as meditation or learning a second language. But they don't show
what the brain is actually doing, Bearer says.

"The MR that we standardly do for human diagnosis is just an image of
your anatomy," she says. Neuroscientists also use a technique called
functional MRI that measures cerebral blood flow, based on the idea that
highly active regions of the brain use more oxygen.

However, the blood-oxygen-level-dependent (BOLD) signal is weaker,
requiring computational analysis, and it mixes both vascular and neural activity, Bearer said. "With BOLD, what you're detecting is a proxy for
neural activity." Bearer and partners Harry Gray at Caltech and Russell
Jacobs at USC have been exploring the potential of MEMRI technology for
some time. In 2020, together with Uselman and post-doctoral fellow Daniel Barto, they reported on the use of MEMRI to demonstrate how exposure to
a frightening stimulus evolves into chronic anxiety.

"The major things that made it possible to learn from this technology
was the computational analysis I did with my students at UNM," Bearer
said. "This review is going to be a go-to reference for all investigators, especially when using this emergent technology."

========================================================================== Story Source: Materials provided by University_of_New_Mexico_Health_Sciences_Center. Original written by
Michael Haederle. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Taylor W. Uselman, Christopher S. Medina, Harry B. Gray, Russell E.

Jacobs, Elaine L. Bearer. Longitudinal manganese‐enhanced
magnetic resonance imaging of neural projections and activity. NMR
in Biomedicine, 2022; DOI: 10.1002/nbm.4675 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220411120714.htm

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