Child Brain Development

Our brain controls conscious (thinking, reasoning, memory and emotions) and unconscious (breathing, digestion, balance, and reflexes) processes. It is made of cells called neurons and is well-organized to handle these functions. Neurons communicate by sending electrical signals through networks of connections. These networks of connections are developed and refined during brain development, based on specific experiences. The brain develops in a predictable sequence (the most basic functions to the most complex). Both genetic inheritance and environment determines how the brain develops.

The formation of neurons begins very early, and by five weeks after conception, the cells in the brain begin dividing rapidly to form the 100 billion plus neurons that are present at birth. The neurons begin to migrate to specific locations in the brain, and synapses begin to form. Development of synapses are stimulated, in the womb, by prenatal temperature, pressure and fetal movements such as kicking, sucking, and other movements.  Myelination of neurons begins with the neurons of the spinal cord and brain stem. Connections in the parts of the brain that control basic survival and reflexes are already well-developed, and myelination in those areas is nearly complete at birth.

At birth, the brain begins a rapid period of growth, with neurons making trillions of connections. The process of forming connections is biologically driven, but experiences also promotes synapse formation. This rapid synapse formation continues throughout early and middle childhood, resulting in production of many more synapses than it will use. The pruning process refines connections based on experience. Connections used regularly become stronger and more complex. Connections not used are eventually pruned to increase efficiency. Babies are born with the ability to hear all languages, but loose the ability though the process of pruning as the language heard regularly develops.

An adolescent’s brain reaches its adult weight by about age fourteen, but myelination and pruning continue during the teen years. Adolescents become more capable of insight, judgment, inhibition, reasoning, and social conscience.  Increased activity in the frontal lobes enables the adolescent to begin comparing or interrelating several concepts at once, however myelination of the frontal lobes is not complete until very late in adolescence (possible 25 to 30).  The regions in the frontal lobe responsible for judgment, planning, assessing risks, and decision-making are the last areas to finish developing. Repeated experiences create complex networks that are strengthened through regular use. Synapse formation continues in adolescence, even as pruning is ongoing.

The brain continues to develop connections throughout adulthood, however the rate of synapse formation is much slower than in childhood. Synapses are formed based only on specific experiences in life. Areas of the brain that are not used regularly may eventually atrophy, thus it is important to keep the brain active.

Next week… what can go wrong?