[单项选择]During the 19th century scientists found that when certain parts of the brain were (36) , men lost the (37) to do certain things. And so people thought that each part of the brain does a (38) job. But modern research has found out that this is (39) , for it is not easy to say exactly what each part of the head does.
In the past fifty years there (40) a great increase in the amount of research (41) on the brain. Chemists and biologists have (42) that the way the brain works is not so simple (43) people had thought. Chemists tell us that about 100,000 chemical changes (44) in the brain every second. Some recent researches also (45) that we remember everything. (46) happens to us. We may (47) to recall the thing we have heard or seen, but it is all kept there in our brains.
Earlier scientists said that the power of (48) brain got weaker and weaker as (49) g