The healthy brains of 120 living people – not members of the Knesset, but other
Israelis and some Europeans – have been scanned with a magnetic resonance
instrument (MRI) to build the world’s first “atlas” of the microstructure of
white matter.
Led by Prof. Yaniv Assaf of Tel Aviv University’s
neurobiology department and the Sagol School of Neuroscience, the CONNECT
project could eventually help identify the first signs of neurological and
psychiatric diseases at an early stage in life so they could be treated early
on.
“Healthy people at age 30 could already have a brain microstructure
with less plasticity and thus be at risk for disease decades later. They could
take medications early to prevent deterioration,” he said. “But that is still
far away.”
White matter is one of the two major parts of the central
nervous system and consists mostly of glial cells and myelinated axons, which
transmit signals from one area of the cerebrum to another and between the
cerebrum and lower brain centers. Appearing pinkish-white to the naked eye, the
myelin tissue is composed largely of lipid (fat) tissue veined with capillaries;
when preserved in formaldehyde for storage, it looks white. It has a different
function than the brain’s “gray matter,” which is composed of neurons (nerve
cells).
While gray matter is involved mostly in cognition and processing,
white matter is actively involved in how the brain learns and coordinates
communication among different brain regions.
The three-year CONNECT
project’s final results have the potential to change the face of neuroscience
and medicine over the coming decade, according to the European Union consortium
of 12 research groups in the project, which will be disclosed at a meeting of
the researchers in Paris.
Assaf told The Jerusalem Post on Tuesday that a
new tool called a “diffusion MRI” looked at the movement of water
molecules.
By measuring that movement, he said, it showed all the
anatomical microstructures of the white matter.
Funding the CONNECT
project, which cost 2.4 million euros, was the EU’s future and emerging
technologies program (FET/ICT). The participants came not only from Israel, but
from the United Kingdom, Germany, France, Denmark, Switzerland and
Italy.
Until now, biomedical research teams in the field of neurobiology
have depended on a “brain atlas” produced by painstaking and destructive
histological examination of the brains of a few people who died and donated
their bodies to science.
But, said Assaf, the new whole-brain atlas is
based on three-dimensional MRI scans of healthy brains from living people, which
were combined. The advanced MRI technology provides unprecedented detail and
accuracy, making an atlas similar to what we might obtain by examining every
square millimeter of brain tissue (around 100 million) with a microscope. The
automated methods turn this arduous process into a much more manageable task and
leaves the brain intact.
The microscopic features mapped in the atlas
included average nerve cell size, diameter and density within the white matter,
and will serve as the reference standard of future brain studies in medicine as
well as basic neuroscience.
The average came from calculating the f i g u
r e s scanned in all 120 healthy subjects, between the ages of 25 and
35.
Assaf noted that the results “provide new depth and accuracy in our
understanding of the human brain in health and disease.”
Historically, he
explained, most neuroscience research has focused on understanding and studying
gray matter and neurons, while white matter has largely been ignored because of
the lack of good research tools to study it, even though white matter comprises
half of the brain’s volume.
The TAU neuroscientist suggested that the
results could be used in the future to characterize and understand
micro-structural changes caused by different neurodegenerative diseases, such as
Alzheimer’s, amyotrophic lateral sclerosis (ALS) or schizophrenia, and to
develop better diagnostic procedures for these and other devastating
conditions.
Assaf said the CONNECT project had no connection to the “Blue
Brain Project” coordinated in Switzerland, whose Israeli participant is Prof.
Idan Segev of the Hebrew University. The Swiss project is an attempt to
reverse-engineer the human brain and recreate it at the cellular level inside a
computer simulation, using slices of living brain tissue to build biologically
realistic models of neurons and networks of neurons in the cerebral
cortex.
Researchers use this data to create simulations on the Blue Gene
supercomputer, which IBM built.
Assaf said that while the two projects
are very different, “in future, they may be able to complement each other and
produce better understanding of how the brain works and how brain disease
occurs.”