How the Brain Develops
A number of factors influence early brain development. These important
factors include genetics, food and nutrition, responsiveness of
parents, daily experiences, physical activity and love. In particular,
parents should be aware of the importance of furnishing a healthy and
nutritious diet, giving love and nurturing, providing interesting and
varied everyday experiences, and giving children positive and
sensitive feedback.
In the past, some scientists thought the brain's development was
determined genetically and brain growth followed a biologically
predetermined path. Now we know that early experiences impact the
development of the brain and influence the specific way in which the
circuits (or pathways) of the brain become "wired." A baby's brain is
a work in progress. The outside world shapes its development through
experiences that a child's senses — vision, hearing, smell, touch and
taste — absorb. For example:
• The scent of the mother's skin (smell)
• The father's voice (hearing)
• Seeing a face or brightly colored toy (vision)
• The feel of a hand gently caressing (touch)
• Drinking milk (taste)
Experiences that the five senses take in help build the connections
that guide brain development. Early experiences have a decisive impact
on the actual architecture of the brain.
Recent equipment and technological advances have allowed scientists to
see the brain working. What scientists have found is that the brain
continues to form after birth based on experiences. An infant's mind
is primed for learning, but it needs early experiences to wire the
neural circuits of the brain that facilitate learning.
Imagine that a child's brain is like a house that has just been built.
The walls are up, the doors are hung. Then you go to the store and buy
electrical wiring, switches, a fuse box and other electrical supplies.
You bring these supplies to the new house and set them on the floor.
Will they work? Probably not. You first must string the wiring and
hook up all of the connections. This is quite similar to the way our
brains are formed. We are born with as many nerve cells as stars in
the Milky Way galaxy. But these cells have not yet established a
pattern of wiring between them — they haven't made their connections.
What the brain has done is to lay out circuits that are its best guess
about what is required for vision, language, etc. Now the sensory
experiences must take this rough blueprint and progressively refine
it. Circuits are made into patterns that enable newborn infants to
perceive their mother's touch, their father's voice and other aspects
of their environment.
Normal sensory experiences direct brain cells to their location and
reinforce the connections between brain cells. We are born with more
than 100 billion brain cells or neurons; we will not grow more. That's
about 10 times the number of stars in the entire Milky Way, and about
20 times the number of people on the planet.
Neurons are the functioning core of the brain. Each cell body is about
one-hundredth the size of the period at the end of this sentence. A
neuron has branches or dendrites emerging from the cell body. These
dendrites pick up chemical signals across a synapse and the impulse
travels the length of the axon. Each axon branch has a sac containing
neurotransmitters at its tip. The electrical impulse causes the
release of the neurotransmitters, which, in turn, stimulates or
inhibits neighboring dendrites, like an on-off switch.
These connections are miracles of the human body. But to understand
their power, you have to multiply this miracle by trillions. A single
cell can connect with as many as 15,000 other cells.
This incredibly complex network of connections that results often is
referred to as the brain's "circuitry" or "wiring." Experience shapes
the way circuits are made in the brain.
A remarkable increase in synapses occurs during the first year of
life. The brain develops a functional architecture through the
development of these synapses or connections.
For example, if a parent repeatedly calls a child a certain name, then
connections will form that allow the child to recognize that name over
time as referring to him and he will learn to respond. From birth, the
brain rapidly is creating these connections that form our habits,
thoughts, consciousness, memories and mind.
By the time a child is 3 years old, a baby's brain has formed about
1,000 trillion connections — about twice as many as adults have. A
baby's brain is superdense and will stay that way throughout the first
decade of life. Beginning at about age 11, a child's brain gets rid of
extra connections in a process calling "pruning," gradually making
order out of a thick tangle of "wires."
The remaining "wiring" is more powerful and efficient. The increase in
synaptic density in a child's brain can be seen in Figure 2. The
interactions that parents assist with in a child's environment are
what spur the growth and pattern of these connections in the brain.
As the synapses in a child's brain are strengthened through repeated
experiences, connections and pathways are formed that structure the
way a child learns. If a pathway is not used, it's eliminated based on
the "use it or lose it" principle. Things you do a single time, either
good or bad, are somewhat less likely to have an effect on brain
development.
When a connection is used repeatedly in the early years, it becomes
permanent. For example, when adults repeat words and phrases as they
talk to babies, babies learn to understand speech and strengthen the
language connections in the brain.
Figure 1. Neurons and connections
Figure 2. Synaptic density in the human brain
Construction of the Brain
We have explored how the brain develops at the cellular level with
neurons and connections. Understanding the different parts of the
brain as a whole and how it functions and develops also is useful.
The brain grows in sequential fashion, from bottom to top, or from the
least complex part (brain stem) to the more complex area (cortex). If
you draw a line from the forehead to the chin and open the brain for a
side view, you would see the brain as it is shown in Figure 3.
Figure 3.Brain: side view
The basic elements of the human brain include the following:
1. The brainstem is at the base of the skull and it controls most
basic life activities, including blood pressure and body temperature.
2. The midbrain is at the top of the brainstem and it controls motor
activity, appetite and sleep.
3. The cerebellum is behind the brainstem and it coordinates movement
and balance.
4. The limbic system is in the central part of the brain and it
controls emotions, attachment and memory.
5. The cortex is the top layer of the brain and is about the depth of
two dimes placed on top of each other. The cortex is the "executive
branch" of the brain that regulates decision-making and controls
thinking, reasoning and language.
The cerebral cortex contains 80 percent of the neurons in the brain.
Because it is the least developed part of the brain at birth and keeps
developing until adolescence and even beyond, the cortex is more
sensitive to experiences than other parts of the brain.
Construction of the brain is somewhat like the construction of a
house. A house is built from the foundation up and different parts of
the structure have different functions. Also, like the brain, once the
architecture is in place, you can continue learning and "add on" or
"decorate." But, if you have to move a wall or add a window, it is
more difficult and expensive than if you had done it earlier in the
building process.
Critical Periods of Brain Development
Brain development proceeds in waves, with different parts of the brain
becoming active "construction sites" at different times. The brain's
ability to respond to experience presents exciting opportunities for a
child's development.
Learning continues throughout life. However, "prime times" or "windows
of opportunity" exist when the brain is a kind of "supersponge,"
absorbing new information more easily than at other times and
developing in major leaps. While this is true especially in the first
three years of life, it continues throughout early childhood and
adolescence. For example, young children learn the grammar and meaning
of their native language with only simple exposure.
While learning later is possible, it usually is slower and more
difficult. Some improvement in most skills is possible throughout
life. However, providing children with the best opportunity for
learning and growth during the periods when their minds are most ready
to absorb new information is important.
Visual and auditory development
The "prime time" for visual and auditory development, or a child's
capacity for learning to see and hear, is from birth to between 4 and
5 years old. The development of these sensory capacities is very
important for allowing children, especially babies, to perceive and
interact with the world around them. During the first few months,
especially, babies need to see shapes, colors, objects at varying
distances and movement for the brain to learn how to see. Babies also
need exposure to a variety of sounds so their brain can learn to
process that information and allow for responsiveness by hearing
something.
Language development
The "prime time" for language development and learning to talk is from
birth to 10 years of age. Children are learning language during this
entire period. However, the "prime time" for language learning is the
first few years of life. Children need to hear you constantly talk,
sing and read to them during these early years. Respond to their
babbling and language efforts.
Children vary in their language development during these first years,
so parents should allow for some variation in children's abilities at
different ages. They should encourage language development, be patient
and seek assistance from a qualified professional if concerns arise
about a child's progress in this area.
Physical and motor development
The "prime time" for physical and motor development in children is
from birth to 12 years of age. Children become physically ready for
different aspects of motor development at different times. Large motor
skills, such as walking, tend to come before the refinement of fine
motor skills, such as using a crayon.
A child needs several years to develop the coordination skills to play
catch with a ball easily, and even then refinement of such skills
continues into a child's early adolescence. Parents should monitor a
child's motor development but be patient since children vary in their
rates of development.
Emotional and social development
The "prime time" for emotional and social development in children is
birth to 12 years of age. Differing aspects of emotional and social
development, which incorporate higher capacities, such as awareness of
others, empathy and trust, are important at different times. For
example, the real "prime time" for emotional attachment to be
developed is from birth to 18 months, when a young child is forming
attachments with critical caregivers. Such development provides the
foundations for other aspects of emotional development that occur as
children grow.
Emotional intelligence is critical to life success. The part of the
brain that regulates emotion, the amygdala, is shaped early on by
experience and forms the brain's emotional wiring. Early nurturing is
important to learning empathy, happiness, hopefulness and resiliency.
Social development, which involves both self-awareness and a child's
ability to interact with others, also occurs in stages. For example,
sharing toys is something that a 2-year old's brain is not fully
developed to do well, so this social ability is more common and
positive with toddlers who are 3 or older. A parent's efforts to
nurture and guide a child will assist in laying healthy foundations
for social and emotional development.
Conclusion
The development of a child's brain holds the key to the child's
future. Although the "first years last forever" in terms of the rapid
development of young children's brains, the actual first years of a
child's life go by very quickly. So touch, talk, read, smile, sing,
count and play with your children. It does more than make both of you
feel good. It helps a child's brain develop and nourishes the child's
potential for a lifetime.
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Friday, April 6, 2012
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