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六级干货》》 作文 |阅读 |翻译 |听力
We sometimes think humans are uniquely vulnerable to anxiety, but stress
seems to affect the immune defenses of lower animals too. In one experiment, for
example, behavioral immunologist (免疫学家) Mark Laudenslager, at the University of
Denver, gave mild electric shocks to 24 rats. Half the animals could switch off
the current by turning a wheel in their enclosure, while the other half could
mot. The rats in the two groups were paired so that each time one rat turned the
wheel it protected both itself and its helpless partner from the shock.
Laudenslager found that the immune response was depressed below normal in the
helpless rats but not in those that could turn off the electricity. What he has
demonstrated, he believes, is that lack of control over an event, not the
experience itself, is what weakens the immune system.
Other researchers agree. Jay Weiss, a psychologist at Duke University
School of Medicine, has shown that animals who are allowed to control unpleasant
stimuli don’t develop sleep disturbances or changes in brain chemistry typical
of stressed rats. But if the animals are confronted with situations they have no
control over, they later behave passively when faced with experiences they can
control. Such findings reinforce psychologists’ suspicions that the experience
or perception of helplessness is one of the most harmful factors in
depression.
One of the most startling examples of how the mind can alter the immune
response was discovered by chance. In 1975 psychologist Robert Ader at the
University of Rochester School of Medicine conditioned (使形成条件反射) mice to avoid
saccharin (糖精) by simultaneously feeding them the sweetener and injecting them
with a drug that while suppressing their immune systems caused stomach upsets.
Associating the saccharin with the stomach pains, the mice quickly learned to
avoid the sweetener. In order to extinguish this dislike for the sweetener, Ader
reexposed the animals to saccharin, this time without the drug, and was
astonished to find that those mice that had received the highest amounts of
sweetener during their earlier conditioning died. He could only speculate that
he had so successfully conditioned the rats that saccharin alone now served to
weaken their immune systems enough to kill them.
1. According to the passage, the experience of helplessness causes rats to
________.
A) try to control unpleasant stimuli
B) turn off the electricity
C) behave passively in controllable situations
D) become abnormally suspicious
2. Laudenslager’s experiment showed that the immune system of those rats
who could turn off the electricity ________.
A) was strengthened
B) was not affected
C) was altered
D) was weakened
3. The reason why the mice in Ader’s experiment avoided saccharin was that
________.
A) they disliked its taste
B) it affected their immune systems
C) it led to stomach pains
D) they associated it with stomachaches
4. It can be concluded from the passage that the immune systems of animals
________.
A) can be weakened by conditioning
B) can be suppressed by drug injections
C) can be affected by frequent doses of saccharin
D) can be altered by electric shocks
5. The passage tells us that the most probable reason for the death of the
mice in Ader’s experiment was that ________.
A) they had been weakened psychologically by the saccharin
B) the sweetener was poisonous to them
C) their immune systems had been altered by the mind
D) they had taken too much sweetener during earlier conditioning
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发表于 2018-12-8 10:20:04