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Home > Research Articles > The Facts About Baby’s Brain

Early Childhood Brain Development Initiative

Thursday, December 13, 2001

We used to think brains were like poker hands. You had to do your best with the one you were dealt at the beginning of the game. Just as the haphazard shuffle of the deck determines which cards you get, the serendipitous co-mingling of your parents' genes laid out a plan for your brain. Your surroundings had no role in that plan. Recent research, however, has completely altered the way we think about brain development. Over the last several years, one study after another has demonstrated that there is more to brain development than heredity and luck. We now know that the first three years of life are critical, and that the way a child' brain develops is greatly influenced by what s/he experiences during that period. Not only does environment affect how large and how fast a child's brain grows, but it helps direct the actual "wiring" of the brain's circuitry.

Human Brain 101
Every baby is born with about 100 billion neurons. Neurons are the special cells responsible for most brain functions, such as thinking, seeing and feeling. We currently believe that those 100 billion neurons are all you get; few or none of them are produced later in life. Neurons connect with each other across tiny spaces called "synapses." These connected neurons join together to form the systems that perform the various functions of the brain. During the first eight months after birth, neurons link up at an amazing pace. By the end of that period, a baby can have as many as 1,000 trillion synapses. These synapses, however, operate on a "use it or lose it" principle. In order to become permanent, the connections must be reinforced through everyday experience and stimulation. Many of those early connections end up in the discard pile, and by age 10 a child has about half as many (500 trillion) synapses, roughly the same number as an adult. The brain develops, in order, from the least complex part--the brainstem, which controls basic involuntary life functions like heart rate and body temperature--to the most complex part--the top layer of the brain, called the cortex, which controls reasoning and abstract thought.

Stimulation "Solders" Connections
In those first months of frenzied synapse formation, far more connections are made than will be kept around permanently. The ones that get used are the ones that will be "soldered." This soldering process takes place when the baby is exposed to outside stimuli. That crucial stimulation comes mainly from other people, particularly parents and child care providers. The brain systems that control vision and language begin forming quite early. Research suggests that what a baby sees and hears at a very young age will have a profound and long-term impact on his/her vision and language skills. Simple interactions may be the most important factors in the development of connections in a child's brain. Through this contact, s/he not only receives the stimuli necessary for the development of sensory functions, but also absorbs the sensation of warm, nurturing care--the "love vibe," if you will--that has proven to be a critical ingredient in healthy emotional development.

Windows of Development
Because the different systems in the brain develop at different times, specific parts of a child's brain must be stimulated within a specific span of time in order to develop normally. If the crucial environmental cues are not present during these periods, the parts of the brain that regulate those functions may not develop appropriately. The window of opportunity for vision, for example, takes place from birth to about six months. Children who are deprived of visual stimulation during this time will not develop the necessary neural connections, and may end up visually impaired. For speech and vocabulary development, the critical window is open between birth and 3 years of age. The sounds a child hears in those years will largely determine the size of his/her adult vocabulary. In addition, children who are not spoken to regularly early in life do not learn to think conceptually as well as those who are exposed to a lot of spoken language. A great deal of emotional development takes place during a child's first 18 months. Infants need loving care from a consistent caregiver. There is no substitute for a nurturing environment. Without it, a child will not attain emotional stability. Between the ages of 1 and 4, children develop the capacity to understand logic and mathematical concepts. There is also a great deal of evidence suggesting that experience with music at an early age may enhance a child's mathematical ability. Children whose math and logic capabilities are not exercised during this stage may have more difficulty learning those skills throughout life.

Impact of Stress, Trauma and Neglect
The flip side of healthy emotional development is the negative impact of stress, trauma and neglect on the developing brain. Research clearly shows that too much stress early in life can have a damaging effect. Abuse and trauma cause the elevated release of a brain chemical called cortisol. When increased levels of cortisol wash over the brain, it can cause certain regions of the brain that regulate emotional response and attachment to be 20-30% smaller than normal. Children who experience trauma or abuse develop adaptive responses that, while appropriate in survival situations, become problematic under normal circumstances. Response patterns displayed by traumatized children include hyperarousal--a state characterized by hyperactivity, anxiety, impulsivity, and sleep difficulties--which is most commonly seen in boys; and dissociation--manifested by daydreaming, fantasy, "going to another place" -- more commonly exhibited by girls. Children need nurturing human interaction. Without it, the cortex and limbic system--the top layers of the brain that control higher levels of thought and help regulate impulsive emotional response--do not grow and organize normally. The combination of neglect and trauma results in a brain that is very good at "primitive" emotional behavior, and not so good at tempering that behavior with more mature, reasoned responses. Because serious neglect and abuse can effect the actual physical development of the brain, children who experience them are at a long-term disadvantage. They can nevertheless be helped through appropriate intervention. The keys to successful intervention are that it start early and be intensive and ongoing.

So What Does It All Mean?
Once a child reaches age 3, 85-90% of his/her core brain structures have been formed. In other words, by that time most of the stuff that can influence a kid's brain, both good and bad, has already taken place. Children living in poverty are at the greatest risk of exposure to things that hinder appropriate brain development. Poverty often means inadequate access to quality child care, stressful family relations, and environments lacking in crucial stimuli, all of which can have a negative impact. Our job as parents, caregivers, educators and policymakers is to make sure that for as many children as possible, those first three years are full of the right kind of stimuli at the right times. We can start by ensuring that all parents and child care providers are knowledgeable about early childhood brain development, and that they have the resources at their disposal to help every child in their care get the best results possible with the brain they were issued at birth.