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Understanding Brain Development in Young Children (page 2)

By Sean Brotherson, Ph.D., Family Science Specialist
North Dakota State University Extension Service

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.

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