Understanding Children Through Neuroscience

A Primer on the Brain

Every brain is composed of several billion brain cells, called neurons , and trillions of connections, or synapses , that help relay electrical messages sent by these neurons throughout the brain and the body. These electrical messages are carried by brain chemicals called neurotransmitters . Brain development is measured in many ways, including monitoring levels of neurotransmitter production, as well as identifying an increase in the number of neuronal connections. New connections are made with every learned behavior or stored critical fact. As these neuronal connections increase, the brain literally grows in size and weight.

Brain development is actually a perfect example of the motto, “Use it or lose it.” The large mass of neurons present in an infant’s brain is waiting to be programmed into synaptic connections. Some connections, like breathing, are preprogrammed. However, the vast majority are learned and developed. During the first ten years of life, the brain is supersaturated with neurons waiting for learned behaviors to pre- sent themselves in order to become synapses.

By the age of two years, a child’s synaptic density begins to gradually decrease through a process referred to as pruning: important connections are becoming reinforced, while other less important ones die back improving the efficiency of the brain. Even with all this pruning, a typical three year old still has nearly 1,000 trillion synapses, which is twice the number of an adult brain, making his brain two and a half times more active than an adult’s.

The late psychologist Myrtle McGraw’s research on child development identified and described the concept of critical periods of learning, developmental windows during which children suddenly reach a period of rapid development and can demonstrate new abilities in many different areas. One of these critical periods falls between the ages of three and five years. Scientists now believe that this same period occurs at a time of high brain plasticity: when the brain is subject to accepting change in neuronal development. The earliest experiences of children, primarily in the first five years of life, play a critical role in determining the ultimate wiring of the brain: how many synaptic connections remain into adulthood. The greater the number of selected neuronal connections, the greater the complexity of the brain, which then has implications for each child’s social, creative, and intellectual abilities. This is why it is so important to capture and take advantage of this critically important window.

As children grow older, the number of potential synapses begins to decline—so much so that by late adolescence, about half of the brain’s synapses have been discarded. If connections are not made, the neurons simply die off. The existing connections that have been made may be reinforced, or crystallized, into habitual behaviors. This means that if a child has developed a particular negative behavior, such as acting out or ignoring other children, and it is not corrected early, it may be more difficult to change later.

Our goal then is to make the most of this critical time of brain plasticity, so that we can ensure that we imprint positive behaviors that will lead to success for children. Parents and teachers can now be assured that intervention—whether it is play therapy, relationship- based therapy, behavioral therapy, or a combination of several methods—does work. Your child may respond to any and all of these methods. In some cases, children can learn to act and learn differently. A shy child does not have to remain a shy child, and an aggressive child is not destined for a life of violence. Although we can’t guarantee that a particular therapy or intervention or approach will change a particular circuitry of the brain, we can say, as Torkel Klingberg writes, that “all types of experience and learning modify the brain.” When we modify our brain, we can change our life.