During the 19th century scientists found that when certain parts of the brain were damaged men lost the ability to do certain things. And so, people thought that each part of the brain controlled a different activity. But modern research has found that this is not so. It is not easy to say exactly what each part of the brain does.

In the past 50 years there has been a great increase in the amount of research being done on 关于the brain. Chemists and biologists have found that the way the brain works is far more complicated that they had thought. In fact many people believe that we are only now really starting to learn the truth about how the human brain works. The more scientists find out, the more questions they are unable to answer. For instance, chemists have found that over 100,000 chemical reactions take place in the brain every second. Mathematicians who have tried to use computers to copy the way the brain works have found that even using the latest electronic equipment they would have to build a computer which weighed over 10,000 kilos. Some recent research also suggests that we remember everything that happens to us. We may not be able to recall this information, but it is all stored in our brains.

ability
n. 能力
exactly
ad. with complete connected or concerned　确切地；精确地
amount　　　　　　　
n. 数量，数额
chemist
n. one who studies and understands chemistry　化学家
biologist
n. one who studies the life of animals and plants 生物学家
biology
n. 生物学
complicated
n. difficult to understand, complex　难懂的；复杂的
chemical
a. of chemistry
unable
a. not able