Children's brains change dramatically in key areas into puberty,
researchers report in a new study that contradicts some
long-standing assumptions about brain development.
The anatomical changes -- described as ``fine-tuning'' --
surprised scientists in the United States and Canada who conducted
the study published Thursday in the journal Nature.
The changes occurred between ages 3 and 15, in some cases years
after the brain has reached its full size. Scientists had believed
that neural development slowed after the first few years of life,
and the brain was essentially organized by the time a child enters
first grade.
In fact, they said, even in the mid-teens the amount of gray
matter in some very active areas can double and neurons can
interconnect rapidly while unneeded cells in other areas are
flushed out.
The research continues two earlier studies of brain development
published last fall. Researchers said they have not determined how
the findings might be practically incorporated into new approaches
to education or child development, but the study suggests how
critically intertwined the stages of brain growth might be to a
child's intellectual and emotional development.
``The teen-age years are a kind of critical time to optimize the
brain,'' one of the study's co-authors, child psychiatrist Jay
Giedd of the National Institutes of Health, told The Washington
Post. ``If a person is doing sports or academics or music, those
are the abilities that will be hardwired.''
In the study, researchers at UCLA, the NIH and McGill University
in Montreal scanned the normal brains of boys and girls ages 3 to
15. Some of the children participated as long as four years.
They saw a wave of growth in the fiber system that relays
information between the brain hemispheres and is a good indicator
of brain activity. The scans also showed new connections being made
in some areas, while other areas shrunk.
In children ages 3 to 6, the team saw burgeoning in the frontal
networks that regulate the planning of new actions.
``In the very youngest children, there really is this furious
growth going on in the frontal circuits of the brain,'' UCLA
neurologist Paul Thompson, who helped develop the brain mapping
technique, told the Los Angeles Times. ``You see this extraordinary
wave of peak growth that proceeds from the front of the brain to
the back.''
In teen-agers up to age 15, the researchers observed peak growth
rates in areas in the middle and back of the brain associated with
associative thinking and language.
The finding reinforces the wisdom of learning new languages
early in life. By high school, the task may become biologically
more difficult.
``The ability to learn a new language declines rapidly after age
12,'' the researchers reported. ``Peak growth rates in linguistic
regions, as well as their attenuation around puberty, may reflect
the conclusion of the critical period for learning languages.''
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On the Net: http://www.nature.com/nature/
