Over the last several years, one study after another has demonstrated that there is more to brain development than heredity. A newborn's brain is remarkably unfinished. Most of its 100 billion neurons have not yet partnered in pathways. A neuron is a brain cell that processes and transmits information through specialized connections with other cells called synapses. The synapse is a communication point between two cells. Neurons are the core components of the nervous system, which include the brain and spinal cord.
While the major brain structures are in place at birth, that’s only the beginning. The real work of brain development is in synapse formation. 1.8 million new synapses are created every second in the first two months. These connections or synapses share data obtained from sensory experiences such as seeing, smelling, touching, and tasting. Forming and reinforcing these connections are the key tasks of early brain development. The earlier and more consistently these connections are made, the more difficult it will be to change or reverse them. First impressions are lasting. Like genetic predispositions, these synaptic links can be overcome, but only with considerable luck and effort. Both are fixed early, and both are relatively irreversible.
By age 3, the infant brain will have grown dramatically, producing hundreds of trillions of connections in the synapses between these cells. The first three to five years of life are a period of incredible growth. The child’s brain is wired by synaptic connections which come from interacting with its environment. How the brain develops hinges on a complex interplay between the genes a baby is born with and the child’s early experiences.
These experiences are expressed in brain circuitry that can now be observed. Brain scans of pre-school children have provided physical evidence of a fast-growing network of neuronal connections. The following images graphically depict the significant physical changes in the child’s brain over the early years.
The ultimate shape of the (child’s) brain….is the outcome of an ongoing active process that occurs where lived experience meets both the inner and outer environment….connections that are used become stronger, even permanent elements of the neural circuitry.” (Schwartz, p. 117-119)
“It is no great stretch to see the implication of these experiments for human development: A young child’s environment directly and permanently influences the structure and eventual function of his or her brain….” (Eliot, p 32)
New terms have been coined to reflect our increased understanding of brain development. When the synaptic connections between neurons are expressed in behavior, they have been called memes. A meme is a way of thinking or acting that can be passed from one mind to another. Because they are reflected in brain circuitry and have a significant impact in a child’s growth and development, memes are analogous to genes.
The larger pattern of connections between the brain’s neurons has been referred to as our “connectome.” (Seung) That is where our genetic inheritance intersects with our life experience, where nature meets nurture. Experiences shape the connectome which changes slowly over time as we learn and grow. Elaborating how the brain’s wiring makes us who we are, Seung has paralleled the connectome to our genome. Both nature and nurture, genes and experience, are seen to have an equally critical role in human growth and development.
