Scientists Map Pattern of Growth in Young Brains
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.
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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
