Growth and Maturation of the Central Nervous System
The hypothalamus is the last area of the central nervous system to mature. The hypothalamus is important because it is responsible for regulating body temperature. This is why premature babies are kept in temperature-controlled environments for a period of time until their hypothalamus is capable or regulating their body temperature for them.
The visual cortex is not developed until an infant is around 11 weeks old. This explains why infants respond to touch and have poor vision after birth. By 8 months, the visual cortex becomes very active and child can register and process what he or she sees.
The growth and maturation of the nervous system continues throughout childhood and reflects the progress of myelination in the body. Neuromuscular coordination progresses in a superior to inferior and proximal-to-distal direction.
The brain will finally reach its maximum weight in young adulthood and will begin to loose weight and volume over the next 60 years. This decline in weight and volume is caused by the damage and death of neurons. The numbers of neurons that die are a small percentage of the total in the brain. Fortunately, remaining neurons are capable of learning throughout life.
Age causes some cognitive declines. Spatial awareness, the perception of speed, decision making, reaction time and working memory are usually the first to go in health people when they are in their 70's. This is because the brain at this age becomes more fragile possibly due to a less efficient clearing of calcium, which can be toxic to the brain. In most cases where calcium is not cleared there can be rapid decline in several of these abilities. Interestingly though, mathematical skills, and verbal fluency do not decline with age.
Alcoholics and professional boxers increase their chance of accelerating brain shrinkage in old age. The CT scans of alcoholics reveal a distinct reduction of brain size and density and boxers increase their risks for atrophy and brain damage with every blow.