Baby Brain Development

The first three years of life are a time of incredible growth in all areas of a baby's development. A newborn's brain is about 25% of its approximate adult weight. But by age 3, it has grown dramatically by producing billions of cells and hundreds of trillions of connections, or synapses, between these cells. While we know that the development of a young child's brain takes years to complete, we also know there are many things parents and caregivers can do to help children get off to a good start and establish healthy patterns for life-long learning.

Basic connections within the brain are made before birth.

During pregnancy, the basic architecture of the brain is formed. The different parts of the brain are in place, for example the brain stem, thalamus, and cerebellum. This initial development also provides basic brain functions that help the baby live.
Although the connections are made during pregnancy, the brain is still immature in that the connections between different parts of the brain are not yet formed.
To some extent formation of the connections depend on exposure to our environment--through relationships and experiences.
Unlike the other organs of the newborn, such as the heart, which is already functioning, as it will throughout the child's life, the brain is not yet ready to perform all the amazing functions it will eventually be able to do. It goes through a series of developmental stages. It is following birth that experience begins to have a greater effect on brain development than it did during pregnancy (although, certain experiences do influence the developing brain during pregnancy, such as maternal health and stress, intake of drugs and/or alcohol, and quality of maternal nutrition).

Babies are born with the ability to learn all the languages in the world.

A Baby's brain is wired to seek out and learn language.
Infants are born with the capacity not just to learn language, but also to learn all languages. As researcher Patricia Kuhl from the University of Washington puts it, infants are "citizens of the world." They are able to perceive the different sounds and patterns of speech of all languages in the world. For example, at birth, Japanese babies can hear the distinction between "r" and "l", although only the "r" sound exists in Japanese. They can still hear the distinction at 6 months of age, but cannot by 12 months of age.
Even in the womb, the infant is turning towards the sound of their mother's voice. The brain is setting up the circuitry needed to understand and reproduce language.
Babies learn to talk by hearing language and having language directed at them in "conversation."
Between 6-12 months, babies begin to fine-tune their ability to perceive the speech sounds of their native language as opposed to non-native language.

A baby's brain has the greatest density of brain synapses by age 3.

Researchers who have studied the brains of humans have shown that there is a pattern of rapid synapse formation during early development.
However, this density does not remain throughout life. After these connections are formed, there is a "plateau " and then a period of elimination, where the densities decrease and resemble adult levels.
This period of elimination begins around early adolescence and continues until at least age 16.
Different parts of the brain undergo synapse formation, plateau, and elimination at different points in development, depending upon when they mature.

The infant brain is making so many connections pre-birth to age 3; the first three years of life are the most critical for brain development.

Although brain connector density is at its highest level in the first three years of life, that doesn't mean that the brain has its greatest brainpower at that time. A great deal of learning goes on after the first three years of life.
However, the first three years are important for laying the groundwork for healthy psychological development. We know that from psychological research; particularly research on parent-child attachment, but not from brain development research. What we know from brain development research right now is that for very specific aspects of brain development, such as the visual system, that critical periods exist and thus a window of opportunity.

Resource: Zero to Three website, Center for Early Education and Development, Irving B. Harris Training Center for Infant and Toddler Development. Talking Reasonably and Responsibly About Early Brain Development. 2001. Regents of the University of Minnesota.