Scientists Map Pattern of Growth in Young Brains
<<...>> Learning: Computer imaging shows changes coinciding with mental
leaps. Findings could guide teaching methods.
By ROBERT LEE HOTZ <mailto:Lee.Hotz@latimes.com>, Times Science Writer
Opening a new window into the mental mysteries of youth, researchers at UCLA
for the first time have directly mapped growing human brains, revealing a
cascade of unsuspected physical changes.
The scientists recorded neural growth spurts that coincide with important
leaps in early learning ability.
The findings, made public today in the journal Nature, may help lay the
foundations for a reassessment of how best to teach language, mathematics
and other crucial mental skills.
Every human brain, the researchers determined, experiences rapid, distinct
waves of almost explosive growth that may determine when it is physically
most receptive to learning new skills or ways of thinking. These growth
spurts occur when the fledgling mental organ is virtually bursting with
vitality--twice as energetic as an adult brain.
"This is potentially a very important discovery," said brain imaging expert
Joy Hirsch at Memorial Sloan-Kettering Cancer Center in New York, who has
been studying brain development in infants.
Until recently, little was known about how normal human brains change as
they grow because conventional medical imaging techniques, such as
computerized tomography (CT) or positron emission tomography (PET) were too
dangerous, invasive or uncomfortable for healthy children. Traditional
autopsy studies revealed almost nothing about neural growth in the young.
Educators have long known that intellectual abilities in language, music and
mathematics must be developed before puberty. They speculated that there are
critical periods when the brain is most open to learning such skills.
But until now they could only guess at the transformations in brain anatomy
that were involved.
"Our biggest surprise was how much the brain is changing," said Jay Gieddes,
chief of brain imaging at the National Institute of Mental Health child
psychiatry branch, who helped perform the study. "It is much more
tumultuous, much more dynamic, much busier than we ever guessed."
To map the changing structure of the developing brain, scientists at UCLA's
neuro-imaging laboratory invented a technique that allows them to precisely
track millions of physical landmarks in the growing brain, keeping it in
focus as it morphs into new shapes over the childhood years.
The technique harnesses conventional magnetic resonance imaging (MRI), which
can take detailed, three-dimensional anatomical images of living brain
tissue, to the power of a graphics supercomputer and three dozen computer
workstations. The end result is a neural journey through time that allows
researchers to track three-dimensional changes in an individual from one
year to the next with a precision never before possible.
"You are looking at a very sensitive measure of how the brain is changing
and how rapidly it is changing," said UCLA neurologist Arthur W. Toga,
director of the neuro-imaging laboratory and the senior researcher
overseeing the study.
A Fingerprint of the Brain
In all, the team followed half a dozen children between the ages of 3 and
15, imaging them repeatedly over the years to create a unique fingerprint of
their maturing brains. The children were scanned at intervals ranging from
two weeks to four years.
Much of the most intense growth was concentrated in a bundle of nerve tissue
called the corpus callosum, which serves as the central communications
conduit between the hemispheres of the brain.
In the youngest children studied--between 3 and 6--the researchers
discovered extremely rapid growth spurts in brain regions responsible for
learning new skills and for learning to think ahead. The scans showed peak
growth rates in frontal circuits of the brain that help focus attention,
maintain alertness and plan new actions.
"In the very youngest children, there really is this furious growth going on
in the frontal circuits of the brain," said UCLA neurologist Paul Thompson,
who helped develop the mapping technique. "You see this extraordinary wave
of peak growth that proceeds from the front of the brain to the back."
Among the youngest children, these communications lines grew fastest where
they are linked to the frontal cortex. "Those are areas that would handle
the learning of new behaviors, the planning of new actions, the overall
organization of new skills," he said.
There also were bursts of growth among these fibers leading to crucial
language areas at the same time.
The researchers found that growth rates in an area of the brain linked to
language were slow between the ages of 3 and 6 but speeded up from 7 to 15
years, when children normally fine-tune language skills. The intense growth
in language areas then dropped off abruptly at puberty, coinciding with the
end of a well-known critical period for language learning.
Older children, between 7 and 13, also experienced an equally intense
buildup of neural circuits in regions that handle mathematical thinking and
the understanding of spatial relationships.
"These investigators have discovered some structural patterns that have
important consequences," Hirsch said. "They are finding growth patterns in
specific [neural] structures that are coming and going with age" that may
have a profound impact on the pace of mental development.
* * *
Mapping Mental Growth
These images show how the human brain changes through childhood. A better
understanding of such changes could shape the future of education by showing
when the brain is physically most receptive to learning. These images
combine scans taken over a period of four years, with the areas of most
intense growth in red, showing growth in regions that handle language,
mathematical thinking and spatial relationships. Areas with the least growth
are in blue.
Sources: UCLA, Nature
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