Developing a Child's Brain - The Windows of Time

As I've mentioned elsewhere, the brain is a passionate interest of mine. One of the most fascinating issues is how people become smart: how brainpower is developed in a child's brain. While the science has been available in textbooks for over a decade, it hasn't been explained well for the general public, and very few adults know about it.

The simplified scientific explanation...

I like to use an architectural metaphor. Developing a child’s brain—her capacity to learn and function—is like building a house. If you lay down a bigger foundation, you can erect a bigger house on it.

And the opportunity to lay down a big foundation occurs during certain developmental “windows of time.” Once the window is closed, the foundation is set. After that, it’s all about house-building on the foundation you have.

The outer layer of the brain, called the cerebral cortex, coordinates perception, physical activity and higher-level thinking. Each of these vastly important functions is handled by different areas of the cortex. Perception is processed by back regions, physical activity is directed by a strip along the top of the cortex, language areas (both linguistic and artistic) are located in the temporal and frontal lobes, and higher-level thinking is handled by the prefrontal cortex—an area located directly behind the forehead.

In a child, each area of the cortex develops at different times, but each area of the cortex grows its network of brain cells the same way: (1) blossoming, (2) pruning, and (3) myelinization. These three phases happen during a limited period of time, during which the foundation is established. Thus, the boundaries of the child's potential are defined once and for all. If the foundation is small, it will be hard to build a big house on it.

During the first phase, blossoming, a frantic period of neuron (brain cell) connections takes place, in which the brain is stimulated to produce many times more connections than it will ever need. This gives that area of the brain enough connections to set up a network to handle the input it receives.

How many brain cell connections survive depends on the demand for that function immediately after blossoming ceases. During the second stage—pruning—brain cells receive incoming signals and process them, while the unused connections die off. In order to see, hear, feel, move, associate and reason, the brain cells need to connect. If demand is intense, more brain cells will try to connect and a higher percentage of neural pathways will survive.

If a child does not use certain brain cell connections during this development period, she loses them forever.

During the third stage, a myelin sheath covers the remaining neurons, creating a kind of insulation that greatly enhances cell-to-cell transmission speed. That’s when learned cognitive skills become powerful and easy.

After the foundation is set, the remaining network can expand, not by growing new brain cells, but by expanding on the foundation conncections. As an individual tries to learn something new, filaments (dendrites) from existing brain cells are stimulated to reach out to other brain cells, creating new connections. This is the value of lifelong learning: it stimulates the growth of dendrites as long as the child (and eventually, the adult) is trying to master new skills and knowledge.

In summary, the greater the stimulation and learning during the initial phase, the more pathways will be possible later in life. After the foundation is in place, a child's basic mental structure is set, once and for all, except for the branching of dendrites within the existing network, which continues throughout life. The all-important question is, when do these time-windows open, and what should a concerned adult do to maximize the child’s cognitive development before they close?

Window #1 - Perception. If you’ve raised a child, you know that a newborn infant’s eyes may be open, but she can’t see anything clearly. She has to learn to see. The overproduction of perceptual neurons takes place while the child is still in the womb. Pruning begins on the first day of life. The child begins a furious process of learning how to see, hear, touch, taste—all the perceptual skills. This foundation learning and pruning takes place during the first six months of life. For maximal development during that time, a child needs a perception-rich environment—ongoing stimulation of all the senses.

Window #2 - Physical activity. The motor neurons also overproduce during gestation, but the window for basic learning and pruning of neurons takes place from 4-18 months. During this period, a variety of new physical challenges will stimulate growth and connection of motor neurons. The more the child does, the more diverse the challenges, the more extensively her foundation for physical capability will be.

Window #3 - Language and categorical thinking. The child learns language, along with the ability to name and categorize everything in her world. Overproduction of the language areas begins while a child is an infant, and pruning starts around the age of 18 months, ending at approximately age 5. During pruning, parents should communicate with a child extensively, giving good, thorough answers to all “what" and "why" questions. This is the time to build vocabulary and to introduce multiple languages. This foundation of linguistic skills will serve the child as she learns factual knowledge during the years before puberty.

Window #4 - Higher-level thinking. This is the last cognitive area to develop. During the onset of puberty, another period of pre-frontal brain cell overproduction begins. This can be an awkward, emotionally and rationally difficult time for a youth, because the areas of the brain needed for reasoning and understanding are disrupted. This is followed by a stage of learning-pruning which establishes the physical foundation for conceptual thinking. During this stage, teenagers need opportunities to solve problems and to seek answers to “major why” questions: scientific, social, cultural, philosophical, and intellectual. If family environment or social norms discourage this kind of discourse and learning, a child may waste this all-important developmental period forever. Ideally, the young person will be curious enough to exercise the conceptual areas of her brain as much as possible during the high school and college years. This developmental period, including myelinization of pathways, continues until the early 20s. After that, her baseline capacity for higher-level thinking and learning is set. During the rest of her life, she will use this foundation to continue specialized learning.

I believe that any adult involved in the raising or teaching of a child needs to understand these critical brain growth periods. Kids are ready for certain kinds of foundation learning at certain times. After these critical windows in time, the opportunities for foundation-building are over. She can continue to learn within the parameters of her limits, but her capacity will have been physically laid down in her brain once and for all. 

The learning of most children isn't guided by these insights. The adults around them have no concept of the developmental windows. So the kids grow into adults in a haphazard way, interacting with whatever environment is at hand. To examine the results, all we need to do is notice the diversity of intelligence in adults.

I strongly advise adults who want to give a child the maximum mental advantages for life to be conscious of these windows and make the most of them. In a way, nothing is more important than this. If you can imagine the behavior of an adult with limited brain power, you can appreciate how important it is to encourage the right kind of learning at the right times.
 
Post by Dennis E. Coates, Ph.D., , Copyright 2010. Building Personal Strength .