Perceptual and Physical Development during Infancy
6.2 Describe the physical development of a child in the first two years of life
Brain Growth and Maturation
The newborn’s skull is relatively large. This is because it must accommodate the brain. The brain is about 25% it’s adult weight at birth. By the age of 2 years, the infants brain is about 75% of its adult weight.
The Building Blocks: Neurons and Their Function
There are significant changes in the maturing nervous system (which consists of the brain, spinal cord and the nerves). The nervous system is made up of long thin, nerve cells called neurons. At birth it contains most of or perhaps all the neurons it will ever have.
Further development consists of the growth and branching of these cells into increasingly dense networks that transmit messages in form of electrical impulses between the brain and the rest of the body. As the nervous system matures the neurons become coated with a fatty insulating substance called myelin. This helps to transmit messages faster and more efficiently. This process is called myelination. The process continues until adolescence. The development of the nervous system allows children to gain increasing control over their motor functions and to experience refined perceptual abilities.
Axons are covered with a fatty coating of cells. This coating, called myelin. It insulates the axon and helps it transmit electrical impulses faster and more efficiently. When myelination occurs in certain regions of the brain, the child gains specific forms of motor skill and muscle control that are associated with those regions. Consequently the timing of an infant’s milestones – the visually directed grasp, rolling over, sitting up, standing, and walking etcetera are directly related to developments in that child’s nervous system. Anything that interferes with myelination affects motor development.
Structure of the Brain
Different regions of the brain develop at different rates before and after birth. The motor regions, which control gross body movements, develop first. The sensory regions, which receive information from the sense organs (nose, eyes, ears, mouth, and skin) develop next. These are the only areas of the brain that function at birth. The sensory and motor regions continue to mature up until the eighth month of life. The association regions, which mediate thought, are the last to develop and their growth continues well into adulthood (Suomi, 1982).