How the brain develops

Brainwave Trust

The majority of brain development takes place between conception and the age of six, with most progress made in the first three years of life. Although brain development in the fetus is initially driven by genes, the experiences of the child, both in the womb and following birth, take an increasingly important role. Most (three-quarters) of the brain actually develops outside of the womb.

At birth an infant's brain is not fully formed. The brain cells (neurons) are all in their correct place, however most are immature with no set function or connection with other brain cells.

Although the brain of a newborn baby is smaller than that of an adult's it is already extremely active and focussed on the need to grow. In order to develop the brain cells need to be activated and to connect with other cells. It is these connections, pathways and networks that will enable the child to develop the powers of vision, language, smell, muscle control and reasoning.

These lines of communication are largely activated and formed by the sensory experiences of the child, such as touch, speech, and movement. As the baby interacts with the environment and caregivers, the brain processes and stores the information. These experiences are crucial as they actually build the brain. They alter the structure of the forming brain and control brain development.

For example, the experience of being touched with warmth and care releases hormones into the infant's brain which will help a child develop the skills to bond with others. Similarly, talking and singing to a child will trigger the brain to start building mental language circuits.

It is during the first six years of life that the majority of the neurons become connected into pathways and networks. However it is the first three years that are particularly important as most (85%) of the core brain structure will have developed by the time the infant is three years old.

The development of the infant's brain will reflect the patterns, intensity, qualities and quantity of experiences that he or she is exposed to.

Research has found that childhood experiences that enrich brain development in these early years produce rich adult brains. The basic experiences of love, security, trust, and affirmation enable children to become competent, intelligent empathetic adults.

Neglect, violence and abuse during these years can damage normal brain development resulting in the profound and permanent disruption to the brain's structure. This can lead to lifelong social, emotional and learning difficulties.

Early experiences, positive and negative, change the actual physical structure of the brain. The resulting structures determine the brain's capabilities and provide the foundation upon which more complex feeling, thinking and behaviour develop throughout the rest of life.

The emerging research has shown that it is not only the quality and intensity of the experiences that affect brain development, but the timing of those experiences.

Neuroscientists have discovered that the brain develops in sequence. There are periods during which the brain is particularly efficient at learning. In science these times are called sensitive and critical periods.

A sensitive period occurs when the neurons required for a process like sight are open and ready to change.

Critical periods are times when established networks can become linked to perform more complex tasks, such as the ability to focus or develop depth of vision.

Information for a skill or a sense flows easily into the brain during these learning periods. However each period is only open for a defined time. Once it closes the brain structure for that skill or sense is complete and becomes more difficult to change. If children miss out on experiences within these time frames, the brain may not develop the connections and, consequently, the skills associated with that developmental phase.

Critical periods occur in phases from birth to the age of twelve. Although learning takes place throughout life, the opportunities and risks are greatest during these early childhood years due to the flexibility of the infant's brain.

- Reprinted with the permission of the Brainwave Trust, a national organisation set up as an independent charity. Brainwave's objective is to have every child in New Zealand raised with care and security. Brainwave aims to reach people with vital information on what is happening inside our baby's brains in the first critical years, and how this impacts on adulthood. Visit their website for more information.