Brain Development

​Early childhood is when the brain develops faster than at any other time in life. And how a young child’s brain develops impacts their future abilities to learn and succeed in school and in life. That’s why your child’s early years are so important.


Your Baby's Brain

The human brain, the command center of the entire body, is ​not fully developed at birth. A newborn baby has all of the brain cells (neurons) they’ll have for the rest of their life, but what really makes the brain work – and enables us to move, think, communicate and just about everything else – are the connections between those cells. And the early years of a child’s life are a crucial time for making those connections.

At birth, the average baby’s brain is about a quarter of the size of the average adult brain. Incredibly, it doubles in size in the first year and keeps growing to about 80% of adult size by age 3 and 90%, nearly full grown, by age 5.

The early years are also when connections between brain cells are being made at an amazing rate – at least one million​ new neural connections (synapses) every second, far more than at any other time in life. This inner wiring enables a very young child to control their body and start to learn about the world.

Different areas of the brain – which are responsible for different abilities like movement, language and emotion – develop at different rates, and eventually brain connections connect with each other in more complex ways, enabling the child to move and speak and think in more complex ways.

After the first three years, the brain begins to fine-tune itself. Connections that are used more often become stronger, while those that are not used are eventually eliminated. This is a normal process, (called pruning), that makes the brain more efficient. Building brain connections is like building muscles: use it or lose it.


1. Experiences Build Brain Architecture
Center on the Developing Child at Harvard University


Making Connections

The early years of a child’s life are the best opportunity for their brain to develop the connections they need to be healthy, capable, successful adults. New scientific research is showing that the connections needed for many crucial skills are formed, or not formed, in these first years – skills like motivation, self-regulation, problem solving, communication and self-esteem. It’s much, much harder for these essential brain connections to be formed later in life.

The really good news is that you can help your baby or young child build the brain connections they need. That’s because brain connections are built through a child’s everyday experiences.

Babies and young children develop the brain connections they need in two ways: through positive interactions with their caregivers, like hearing a lullaby, and by using their senses to interact with the world around them, like reaching for a toy. Different stimuli help build different connections. It’s a child’s daily experiences – the amount and quality of care, stimulation and interaction a child receives in their first days, weeks, months and years – that determines which brain connections develop and will last for a lifetime.


2. Serve & Return Interaction Shapes Brain Circuitry
Center on the Developing Child at Harvard University


Young Children Develop Through Relationships

There are many things that influence a child’s development, but the most important are their relationships with the adults in their life. Loving relationships with warm, responsive, dependable adults are essential to a child’s healthy development. These relationships begin at home, with parents and family, but also include child care providers, teachers and other members of the community.

From birth, young children serve up invitations to engage with their parents and other adult caregivers in their lives. Babies do it by cooing and smiling and crying; toddlers are able to communicate their needs and interests more directly. Each of these little invitations is an opportunity for the caregiver to either be responsive or unresponsive to the child’s needs. This "serve and return" process is fundamental to the wiring of the brain. Parents and caregivers who give attention and respond and interact with their child are literally building the child’s brain. That’s why it’s so important to talk, sing, read and play with young children from the day they’re born, to give them opportunities to explore their physical world, and to provide safe, stable and nurturing environments.

Studies have shown that babies who experience more of these types of positive interactions will go on to be healthier and more successful in school and in life. Unfortunately, the opposite is true as well. Young children who are deprived of caring interaction do not develop as many brain connections, and that has negative long-term impact.


3. Toxic Stress Derails Healthy Development
Center on the Developing Child at Harvard University


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