1. Early childhood
The brain continues to develop after birth. It doubles in weight after 6 months and weighs about half that of the adult brain. Brain development proceeds at an uneven pace occurring between 3 and 10 months and between 15 and 24 months. There are 100 billion neurons or brain cells at birth which conduct nerve impulses. The neurons are nourished by glial cells which are responsible for the increase in brain size. The glial cells are also responsible for the production of myelin, a fatty substance that forms the covering of the axon of the neuron which enables the neuron to make contact with other nerve cells, thereby transmitting neural messages. It is the myelin substance that conducts impulses at higher speeds. As myelination continues the child’s ability to control attention increases.
2. Middle childhood
Ninety-five percent of brain growth reached at the age of 9. Growth is characterized by interrelated processes namely:
a. Cell proliferation – consists of the over production of neurons and interconnections.
b. Cell pruning – a continuous process which involves the selective elimination of excess cells and the cutting back of connections.
These two processes afford fine-tuning of neural development through experience such that frequent interconnections are retained while the infrequent are pruned.
During this period, the neurons of the association areas – parts of the brain where sensory, motor and intellectual functions are linked are myelinized to some degrees.
3. ADOLESCENCE
During this period, there are 2 major brain growth spurts, one occurring between ages 13 to 15 and the second beginning around age 17 and continues into early adulthood.
In the first spurt, the cerebral cortex becomes thicker and neuronal pathways become more efficient. More energy is produced and consumed by the brain. Studies reveal that major changes in brain organization occur between ages 13 and 15. The second brain growth spurt has the frontal lobes of the cerebral cortex as focus of development.
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