The brain is the most complex part of the human body. This organ that weighs in at about 1.5 kg, is the seat of intelligence, interpreter of the senses, initiator of body movement, and controller of behaviour. It is the crown jewel of the human body.
The brain is like a committee of experts. All of its parts work together, but each part has its own special properties. The main parts are the forebrain, the midbrain, and the hindbrain. When people see pictures of the brain it is usually the cerebrum in the forebrain that they notice. The cerebrum is the source of intellectual activities. It holds your memories, allows you to plan, enables you to imagine and think. It allows you to recognize friends, read books, and play games.
The cerebrum is split into two halves (hemispheres) by a deep fissure. Despite the split, the two cerebral hemispheres communicate with each other through a thick tract of nerve fibres that lie at the base of this fissure. Although the two hemispheres seem to be mirror images of each other, they are different. For instance, the ability to form words seems to lie primarily in the left hemisphere, while the right hemisphere seems to control many abstract reasoning skills.
For some as-yet-unknown reason, nearly all of the signals from the brain to the body and vice-versa cross over on their way to and from the brain. This means that the right cerebral hemisphere primarily controls the left side of the body and the left hemisphere primarily controls the right side. When one side of the brain is damaged, the opposite side of the body is affected. For example, a stroke in the right hemisphere of the brain can leave the left arm and leg paralysed.
When the brain is healthy it functions quickly and automatically. But when problems occur, the results can be devastating. About 20 percent of New Zealanders will experience some form of brain disorder in their lifetime. This will affect us all since we are the family and friends of this 20 percent. Thanks to science, we know more about the brain now than in previous centuries. Because of the accelerating pace of research in neurological and behavioural science and the development of new research techniques, gains in knowledge and treatments will continue to benefit our lives.
