私醫聯招 英文歷屆試題｜第 443 題

With more than 10 billion nerve cells, the human brain is by all odds the most complicated thing in the universe. Scientists still know relatively little about how the brain works. Averagely, the adult human brain weighs about three pounds and bulks the size of a grapefruit. In men the average weight is about 1370g; in women about 1200g.

The brain is the physical organ most associated with mind, a non-technical term used to refer to the functions of the brain like problem-solving and remembering. It is part of the invisible world of thought, including cognitive aspects such as perception and imagination, as well as noncognitive aspects such as emotion. No one knows yet how mind and brain are related. In other words, no one knows much about what happens in the brain when it is functioning.

It is suggested that man ought to do better than he does with his much greater number of nerve cells in that the ant achieves its marvelous community organization with only 250 nerve cells. However, the ants run their society by instinct not by thought. In fact, it seems likely that ants cannot think at all; they use their nerve cells for receiving impressions of the outside world, not for coping with it.

Deep inside man's brain is a core called “old brain,” which dinosaurs possessed millions of years ago. This core plays a part in arousing and satisfying primitive needs like hunger and sexuality. The old brain is covered by the dome of the neocortex, or “new brain,” which enables man to look ahead. It is the brain's analytical computer, processing data and responsible for sensory perception, attention, memory, etc. Of all the forms of life, only man has the ability to plan for his future.