Environmental Exposures Dictate Early Brain Development

At birth, a baby's brain already contains nearly all of the neurons it will ever have. These neurons serve as the basis for behavior, memory, and learning. From cognitive function and abstract thinking to survival instincts like hunger and fear, neurons are the tools the body uses to process information.

Neurons communicate with one another through connections called synapses. The brain's vast network of synapses is the information super highway that conveys information from neuron to neuron. The more information a given neuron needs to process, the stronger its associated synapses become. Meanwhile, synapses that are rarely used are considerably weakened. Larger and denser synapses indicate a higher amount of development between certain neurons.

The activity of neurons and synapses is directly affected by the body's external environment. A brain reacts to input from the environment it consistently encounters – whether it is a good or bad environment. In an optimal environment, a brain will develop the neurons and synapses associated with cognitive function, self-confidence, and self-control. In a toxic environment, a brain will develop the neurons and synapses associated with fear or uncertainty.

The brain prioritizes the development of synapses most required to cope with its environment. When a brain is continually exposed to stress and threats of violence, the appropriate synapses are developed, often at the expense of synapses associated with vital critical thinking skills that are needed to perform in school or in the workforce. In extreme cases, the brain's adaptation to a negative environment may inhibit the development of various body organs vital to physical and mental health.

Most importantly, more synapses are created during the first three years of life than during any other time. As a result, early childhood experiences often have life-long effects. While early brain development is influenced by a genetic blueprint, environmental stimuli can affect the way that genes are expressed.

For more information on baby brain development, please visit our Baby and Brain page.