by Dawn Ramsburg
Introduction
Much attention has been focused in recent years on the importance of
the early years for young children's healthy mental development.
Activities have included a plenary session devoted to the need for
investment in children from birth through the first three years of life at
the National Governors Association Meeting (February 1997), and a guest
appearance by Hillary Rodham Clinton at the April 1997 Meeting of the
Society for Research in Child Development, where she reiterated the
importance of early experience in child development and described a
conference the White House will host in late April on early development
and learning. A primary reason for this increased attention was the 1994
release of Starting Points: Meeting the Needs of Young Children by
the Carnegie Corporation of New York. This report documented the
burgeoning literature on young children's emotional, social, physical,
intellectual, and brain development, and concluded that "how children
function from the preschool years all the way through adolescence, and
even adulthood, hinges in large part on their experience before the age of
three" (p. 6).
Why the increased attention on the early years? Since the 1970s, strong
evidence has emerged that suggests that activity, experience, and
stimulation can alter brain development. In recent years, technological
advances have enabled researchers to make important advances and
discoveries in brain research. As a result of the emerging evidence, a
shift is taking place in traditional views of development in young
children.
Emerging Views on Brain Development in Young Children
In the past, the two dominant views on children's development proposed
that children either came into the world genetically pre-programmed
("nature"), or that they were a "blank slate" on which
their environment shaped their development ("nurture"). The
debate over nature vs. nurture is fading quickly, however, as scientists
now are investigating the complex ways in which genes and environment
interact. Scientists understand that both nature and nurture shape brain
development, and that each set of influences is dominant to varying
degrees at various points in time.
Brain Development in the Prenatal Period
Before birth, nature is the dominant actor in brain development,
although the environment also plays an important role. According to Dr.
Pasco Rakic, a professor of neuroscience at Yale University, "The
number of neurons and the way that they are organized is determined by
heredity" (Jabs, 1996, p. 24). Scientists know that during the third
week of pregnancy, a thin layer of cells in the developing embryo folds
inward to create a fluid-filled cylinder called the "neural
tube" (Berk, 1994, p. 99). It is in the neural tube where the
production of neurons, the brain cells that store and transmit
information, begins--at the rate of 250,000 per minute (Nash, 1997, p.
52).
By the end of the second trimester, the process of producing neurons is
completed. No more neurons will ever be produced again in an
individual's lifetime. Some neurons are programmed for specific functions
such as breathing, controlling the heartbeat, regulating body
temperatures, or producing reflexes. But, for the most part, neurons are
not designated to perform specific tasks, and thus brain development is
not complete at this point.
Although nature or genetics plays the dominant role in the prenatal
period, the environment is important at this time as well. Researchers
have found that environmental factors such as maternal malnutrition,
substance abuse (including alcohol, smoking, illegal drugs, and use of
over-the-counter medications), exposure to chemicals or radiation, and
viral infections (such as measles) can lead to adverse effects on the
developing brain.
Brain Development Following Birth
While newborns are born with all the neurons they will ever have, a new
phase of brain development begins after birth--the wiring phase. Following
birth, each of the brain's 100 billion neurons creates links to thousands
of others (Nash, 1997, p. 53). This process is accomplished as neurons
produce a web of wire-like fibers called axons (which transmit
signals) and dendrites (which receive signals). Once axons make
their first connections, the nerves begin to fire (Nash, 1997, p. 53). It
is at this point that the environment begins to take over in the process
of brain development. Scientists often describe this stage as the
equivalent of creating telephone trunk lines between the right
neighborhoods in the right cities. At this point in development, the brain
has to sort out which wires belong to which house (Nash, 1997, p. 53). It
is with these maps that learning will take place (Carnegie, 1994).
The most important factor in this process of developing connections is
stimulation, or repeated experience. Scientists now know that in the
months after birth the number of synapses increases from 50 trillion to
1,000 trillion (Carnegie, 1994). Neurons that are stimulated by input from
the surrounding environment continue to establish new synapses. Those that
are seldom stimulated soon die off. According to Dr. Harry Chugani, a
professor of pediatric neurology at Wayne State University, "It's
like a highway system. Roads with the most traffic get widened. The ones
that are rarely used fall into disrepair" (Nash, 1997, p. 26).
Critical Periods in Brain Development
Because of the evidence emerging on synaptic development, scientists
believe that appropriate stimulation of the child's brain is critically
important during periods in which the formation of synapses is at its peak
(Berk, 1994). It is during these critical periods, or windows of
opportunity that exist for different brain functions, when a child's
experiences can make the most difference. And, for some areas, if the
connections between neurons are not developed during these critical
periods, they will never develop at all.
One area of brain development that has received much attention in
determining its critical period is vision. It has been found that the
synapses associated with vision multiply quickly in 2- to 4-month-olds and
keep increasing until around 8 months (Jabs, 1996, p. 25). At 8 months,
each neuron is connected to 15,000 other neurons (Begley, 1996, p. 56).
This rate makes sense when we realize that infants have limited motor
skills and spend much waking time watching the world around them. Yet
researchers have found that a baby whose eyes are clouded by cataracts
from birth will, despite cataract removal surgery at the age of 2, be
forever blind. This finding indicates that the window of opportunity for
vision does not stay open for a long period of time.
Implications of These Findings
Does this research mean that it is too late to make a difference in the
brain development after age 3? Absolutely not. Researchers have found that
the brain during the first years of life is malleable, citing instances in
which very young children who suffer strokes or injuries that wipe out an
entire brain hemisphere still mature into highly functioning adults (Nash,
1997, p. 54). Children have also been found to overcome emotional and
physical abuse suffered during the first year, presumably because of
"plasticity," or the ability to rewire damaged brain areas.
It is also important for parents not to push children during this
period and provide too much stimulation. Parents who try to rush children
through the stages of development are asking children to function with
capacities that may not be ready to be used (Jabs, 1996, p. 25). In
addition, if parents try to push children, they may form connections
between certain activities and stress. Parents who try to force a child to
complete a puzzle before he or she is developmentally ready may decrease
the child's disposition to do the puzzle or engage in related activities
because of the stress connection.
With few exceptions, with vision as perhaps one notable exception, the
windows of opportunity in brain development do not close abruptly. What
research findings do indicate is the importance of helping children
develop a sound foundation in early learning, so that they have the
building blocks for a lifetime of learning. This foundation comes from
stimulating education and child care experiences during the early years.
~~~~~~~~~~
References
Begley, S. (1996, February 19). Your child's brain. Newsweek, 127,
55-62.
Berk, L. (1994). Infants and children: Prenatal through early
childhood. Boston, MA: Allyn and Bacon.
Carnegie Corporation of New York. (1994). Starting points for young
children. New York: Carnegie Corporation of New York.
Jabs, C. (1996, November). Your baby's brainpower. Working Mother,
19, 24-28.
Nash, J. (1997, February 3). Fertile minds. Time, 149,
48-56.
© 1997, ERIC Clearinghouse on Elementary and Early Childhood Education.
NLD on the Web! has complied with the copyright
permission requirements of NPIN Parent News and ERIC-EC.
Source - This article first appeared in the
April 1997 issue of the NPIN
Parent News (Vol.3, No.4), a publication of the ERIC Clearinghouse on Elementary and Early Childhood Education, University of Illinois at
Urbana-Champaign, Children's Research Center, 51 Gerty Drive, Champaign, IL 61820-7469.
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