ABSTRACT
DEVELOPMENT The critical period for brain growth appears to be during the first sixteen weeks of life. At birth, a baby’s brain weighs approximately 25 per cent of its future adult weight. By the time the child is two years old the brain has increased to 75 per cent, and by six years, 90 per cent of its eventual weight. This, then, indicates phenomenal growth of the central nervous system during the early years. Peripheral nerves continue to become myelinated (grow fatty sheaths to increase nerve transmission rate) and fine physical control appears as the child moves towards adult status. With the unique environment impinging on every waking and sleeping hour, this plastic nervous system constantly matures and changes as demands are put upon it. The nervous system coordinates and controls all body systems to a greater or lesser degree and, together with the hormones of the endocrine system, fine-tunes a delicate homeostasis.
