X-Message-Number: 12355
Date: Tue, 31 Aug 1999 21:25:38 -0400
From: Jan Coetzee <>
Subject: New method to visualize the brain

St. Louis, Aug. 31, 1999 -- Researchers have developed a way to
visualize
nerve fiber bundles that transmit information between different areas of

the
living human brain. Their study provides new information on the orderly
pattern of these fiber connections and may one day lead to improvements
in
brain surgery, diagnosis of brain ailments, and understanding of
neurological
diseases.

"This technique will enable scientists to make more detailed maps of
connections between different parts of the brain. In particular, this
technique can provide diagrams of how the brain is wired and which parts
of
the brain talk to which other parts," says Thomas E. Conturo, M.D.,
Ph.D.,
assistant professor of radiology at Washington University School of
Medicine
in St. Louis. "By knowing that, scientists may be able to identify
abnormal
connections between brain areas that might be important in diseases such
as
schizophrenia."

The study, published in today's issue of Proceedings of the National
Academy
of Sciences, also may provide a way to tell if behavioral differences
among
people partly result from differences in the way their brains are wired.

Conturo, the lead author, also notes that wiring diagrams could be used
to
study how the recently recognized process of "re-wiring" occurs in brain

ailments such as stroke.

Scientists' understanding of the wiring of the human brain has come
primarily
from studies of animals, which lack many of the higher brain functions
of
humans. A nine-member team of physicists, computer scientists,
neuroscientists, radiologists and anatomists spent three years
developing
the
variation of magnetic resonance imaging (MRI) and analyzing data to
provide
detailed maps of brain wiring in living humans.

The MRI fiber tracking method monitors the random movements of water
inside
and around nerve cells. The cells have long fiber extensions that
transmit
electrical impulses to communicate with other nerve cells. These fibers
are
arranged in parallel bundles like cables in a telephone line. Water
tends
to
move more easily along the length of these cables. Using an MRI method
that
has high sensitivity to water movements, the researchers traced these
cables
by following the preferred direction of water movement.

The research team studied four volunteers and determined the wiring
layout
of
fiber bundles throughout the brain, which primarily were found in white
matter regions where a white fatty substance insulates the bundles. The
researchers then selected certain areas for closer evaluation.

They first studied fiber bundles in the back of the head that cross
between
the two sides of the brain. One group of the crossing fibers went
forward
and
to the top of the brain, whereas another group went to the back of the
brain
where visual information is processed. The two groups of fibers came
very
close together to run side-by-side when crossing to the other side of
the
brain, but their wires did not intermix.

Next, the researchers traced longer fiber bundles that transmit visual
information from the eyes to the brain. Fibers that are used for seeing
different parts of the visual world were identified. The researchers
note
that such detailed 3-D information on human brain wiring could guide
surgery
in the future. "For example, a surgeon might want to use these data when

deciding how to remove a cancer without cutting cables that are used for

vision," Conturo says.

The research team then showed that MRI fiber tracking could reveal which

parts of the brain work together to perform a specific task. Using
functional
MRI, the researchers determined what brain areas are activated when a
person
is watching a flashing light. Then, using MRI fiber tracking, they
determined
that the brain areas joined together and that direct fiber connections
exist
between the areas.

Finally, the researchers identified complicated connections between
several
brain areas involved in higher level thinking skills such as speaking,
paying
attention, and multiplying numbers. The fiber bundles that connected to
different brain areas often ran side-by-side to form larger cables
without
mixing their wires, like driving onto a highway from an on-ramp having
its
own lane. "We were surprised and excited to find that the brain
circuitry
was
wired in such an orderly fashion," Conturo says.


###
GRAPHICS: A high-resolution, color image of a fiber tract positioned on
a
3-D
model of the human head is available from the Office of Medical Public
Affairs upon request. Copies of the article are available from the PNAS
News
Office 202-334-2138, or email 

Conturo TE, Lori NF, Cull TS, Akbudak E, Snyder AZ, Shimony JS,
McKinstry
RC,
Burton H, Raichle ME. Tracking neuronal fiber pathways in the living
human
brain. Proceedings of the National Academy of Sciences, 96, 10422-10427,

Aug.
31, 1999.

Nicolas F. Lori, a predoctoral physics candidate, developed the computer

graphics algorithms and fiber tract selection methods, analyzed data,
and
assisted with development of algorithms for computing fiber tracts.
Erbil
Akbudak, Ph.D., research instructor in radiology, developed the MRI
scanning
methods and data collection algorithms. Abraham Z. Snyder, Ph.D., M.D.,
research scientist in radiology, developed algorithms for image
processing
and fiber tract computation. Joshua S. Shimony, M.D., Ph.D., clinical
fellow
in radiology, developed the data analysis to compute the direction of
water
movement. Harold Burton, Ph.D., professor of neurobiology and radiology,

provided anatomical expertise and assisted with the interpretation of
results. Marcus E. Raichle, M.D., professor of radiology and neurology
and
co-director of the Division of Radiological Sciences, suggested that
data
on
nerve fiber directions could be used to study interactions among brain
areas,
and assisted with the interpretation of results.

This research was funded by the McDonnell Center for Higher Brain
Function,
the Charles A. Dana Foundation Consortium on Neuroimaging Leadership
Training, and the National Institutes of Health.

The full-time and volunteer faculty of Washington University School of
Medicine are the physicians and surgeons of Barnes-Jewish and St. Louis
Children's hospitals. The School of Medicine is one of the leading
medical
research, teaching and patient care institutions in the nation. Through
its
affiliations with Barnes-Jewish and St. Louis Children's hospitals, the
School of Medicine is linked to BJC Health System.

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