次の英文を読み、下記の設問に答えなさい。

Anyone who knows the opposite sex well will tell you that, at times, men and women seem to be from different planets. The sexes often appear to think very differently from each other. However, until recently, researchers thought that these differences were caused by two things: social pressures, which have encouraged males anti females to behave in certain ways, and secondly, hormones – chemical signals which tell different parts elate body, including tile brain what to do. Researchers didn't think the brain itself caused differences – on the contrary, they thought the brain's structure was mostly the same for both sexes. Interestingly, (    1    ), new research is casting doubt on these assumptions: There may be a third factor that had not previously been considered seriously. Research is now revealing that male and female brains have many differences in structure. There are also differences in how the various parts of the brain are linked and in the chemicals that transmit messages between neurons. All this suggests that there is not just one kind of human brain, but two.

This is giving neuroscientists something of a headache, because most of what we know about the brain comes from studies of male animals and male humans. Generally, neuroscientists avoided using females in their research. This was (    2    ) the monthly ups and downs of female hormones made it more complicated to interpret the results. lf even a small proportion of what has been (6)inferred from these studies does not apply to females, a huge body of research could be wrong.

Male-female differences in brain structure are now becoming clear. In the past, the only structure that had long been known to differ (7)slightly in males and females was the hypothalamus^*1, which helps to control basic human instincts such as regulating food intake. But new technology has helped scientists find other differences. For a start, the relative sizes of many of the structures inside female brains are different from those of males. In 2001, Jill Goldstein of Halyard Medical School and colleagues measured and compared 45 brain regions in healthy men and women. They found that parts of the frontal lobe^*2, which houses decision-making and problem-solving functions, were proportionately larger in women, as was the limbic cortex^*3, which controls emotions. Other studies have found that hippocampus^*4, involved in short-term memory and spatial navigation, is proportionally larger in women - perhaps surprisingly (    3    ) women's reputation as poor map leaders. In men, proportionately larger areas include the parietal cortex^*5, which processes signals from the sensory organs and is involved in spatial perception, and the amygdala^*6, which controls emotions and social behavior.

Larry Cahill, a neurobiologist at the University of California, Irvine, has found evidence that, in some circumstances, people of different sexes use the same brain structures differently. In brain-imaging experiments, he asked groups of men and women to remember images they had been shown earlier. These images were chosen because they produce a strong emotional reaction. Both men and women (8)consistently used the amygdala to complete the task. However, the men used the right side of the amygdala, while the women used the left side. What's more, each group remembered different aspects of the image. The men remembered the (9)gist of the situation whereas the women concentrated on the details. This suggests men and women process information from emotional events in very different ways.

Research also suggests that the brain circuits that suppress pain may be different in males and females. In fact, a lot of research - but not all - suggests that females experience more pain than males. Some time ago, doctors noticed that some painkillers have different effects on men and women. For example, nalbuphine^*7 works better for women than for men - in fact, it sometimes actually increases pain in men! Others appear to work better on men. So, with increasing understanding of how painkillers work, in the future we may be able to create painkillers that are more effective for women. However, developing drugs is very expensive, so we will probably have to wait for more research to show whether this will be (10)financially worthwhile.

Another area where there are gender differences is mental health. For example, women appear to suffer from depression twice as often as men, and their brains typically produce about half as much serotonin - a neurotransmitter^*8 linked to depression. Recently, Anna-Lena Nordstrom from the Karolinska Institute in Stockholm, Sweden found that healthy women have more of the most common type of serotonin receptor^*9 than men but fewer serotonin transporters^*10, which are needed to recycle serotonin. It hasn't been shown that variations of the set-up make some women more prone to depression, but Nordstrom points out that transporter differences between men and women are (    4    ) particular interest because this is where antidepressants like Prozac^*11 act, and because there is evidence that women respond better to such drugs than antidepressants that act on neurotransmitters other than serotonin.

Males may be less likely to suffer from depression, but this is balanced by other issues. Boys are more likely than girls to be diagnosed with a wide range of problems affecting brain systems, such as autism^*12, Tourette's syndrome^*13, dyslexia^*14, stuttering^*15 is, attention-deficit disorder^*16, and early-onset schizophrenia^*17. So, a new approach to designing medicines, with one gender in mind, may also (    5    ) males in the future. Again, we have to wait for further research.

出典 [© 2008 Reed Business information UK. all rights reserved. Distributed by Tribune Media Service, Used with permission. ]
[From Discover, July 5, 2007 © 2007 Discover Media. All rights reserved. Used by permission and protected by the Copyright Laws of the United States. The printing, copying, distribution. or retransmission of this Content without express written permission is prohibited. http://diseovermagine.com/2007/brain/she-thinks]

注:
• ^*1 hypothalamus 「視床下部」
• ^*2 frontal lobe 「前頭集」
• ^*3 limbic cortex 「辺縁皮質」
• ^*4 hippocampus 「海馬」
• ^*5parietal cortex 「頭頂葉皮質」
• ^*6amygdala 「扁桃体」
• ^*7nalbuphine 「ナルブフィン」(合成麻薬性鎮痛剤)
• ^*8neurotransmitter 「神経伝達物質」
• ^*9serotonin receptor 「セロトニン受容体」(セロトニンと結合し、細胞内に信号を伝達する膜タンパク質)
• ^*10serotonin transporters 「セロトニン輸送体」(セロトニンが神経細胞からシナプス間際に放出された後に、それを再び元の神経細胞内に取り込む働きをする膜タンパク質)
• ^*11Prozac 「プロザック」(抗鬱剤の一種。選択的セロトニン再取り込み阻害剤)
• ^*12autism 「自閉症」
• ^*13Tourette's syndrome 「トゥレット症候群」
• ^*14dyslexia 「失読症」
• ^*15stuttering 「吃音症」
• ^*16attention deficit disorder 「注意欠陥障害」
• ^*17early-onset schizophrenia 「若年発症統合失調症」

• 問1 本文中の(1)～(5)の空欄に入る最も適切なものを、それぞれ(a)～(e)の中から一つずつ選びなさい。
  • (1)
    • (a) but
    • (b) in short
    • (c) therefore
    • (d) though
    • (e) while
  • (2)
    • (a) because
    • (b) despite
    • (c) instead
    • (d) so that
    • (e) why
  • (3)
    • (a) if
    • (b) in case
    • (c) given
    • (d) provided
    • (e) supposedly
  • (4)
    • (a) at
    • (b) of
    • (c) of
    • (d) with
    • (e) without
  • (5)
    • (a) benefit
    • (b) corrupt
    • (c) disguise
    • (d) endanger
    • (e) frustrate
• 問2 本文中の(6)～(10)の語(句)に最も近い意味のものを、それぞれ(a)～(e)の中から一つずつ選びなさい。
  • (6) inferred
    • (a) gathered
    • (b) inhibited
    • (c) mistaken
    • (d) neglected
    • (e) refused
  • (7) slightly
    • (a) a great deal
    • (b) by no means
    • (c) extremely
    • (d) significantly
    • (e) somewhat
  • (8) consistently
    • (a) contradictorily
    • (b) rarely
    • (c) regularly
    • (d) roughly
    • (e) unpredictably
  • (9) gist
    • (a) essence
    • (b) fault
    • (c) nonsense
    • (d) positive
    • (e) trivia
  • (10) financially worthwhile
    • (a) ethical
    • (b) harmless
    • (c) nutritious
    • (d) profitable
    • (e) therapeutic
• 問3 下記の(11)～(15)の各文の内容が本文と一致するように、書き出しに続く最も適切なものを、それそれ(a)～(e)の中から一つずつ選びなさい。
  • (11) Judging from the passage, the part of the brain that gives people a feeling of hunger is most likely to be the           .
    • (a) amygdala
    • (b) frontal lobe
    • (c) hippocampus
    • (d) hypothalamus
    • (e) parietal cortex
  • (12) Jill Goldstein of Harvard Medical School found that            .
    • (a) differences between men and women in their behaviors were mainly caused by social pressures and hormones
    • (b) it would cause unexpected problems to include women in brain research
    • (c) men and women process information in very different ways by means of using the opposite sides of the amygdala
    • (d) women appeared to suffer from headaches twice as often as men because of the shortage of a certain brain chemical
    • (e) there were differences between men and women in the sizes of structures inside the brain
  • (13) According to the passage, it’s true that            .
    • (a) brain research has traditionally been conducted on both male and female animals
    • (b) nalbuphine relieves pain more effectively in men than in women
    • (c) men and women are not affected the same way by all painkillers
    • (d) researchers suggests that males and females use the same circuits to block pain
    • (e) there will never be painkillers designed especially for women in the future
  • (14) According to the passage, it is NOT true that           .
    • (a) women seem to experience more depression than men
    • (b) compared with men, women have more serotonin transporters and receptors
    • (c) boys are generally more likely to suffer from a broad variety of brain system disorders than girls
    • (d) men normally produce approximately twice as much serotonin as women
    • (e) it appears that women respond better to drugs that affect the regulation of serotonin than those which work on other neurotransmitters
  • (15) The main idea of the whole passage is that           .
    • (a) neuroscientists have found no great differences between male and female brains
    • (b) the brain has different parts, each of which carries out a different function
    • (c) the reason many researchers are failed to include lei ales in their studies is understandable
    • (d) a neuroscientist has found that males and females sometimes use the same structure of the brain differently
    • (e) researchers have begun to make new discoveries about how male and female brains are different