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 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 dont 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 mice to avoid saccharin 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. Laudenslagers 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 Aders 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 Aders 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
参考答案:
1.C 2.B 3.D 4.A 5.C
US envoy seeks Chinese backers for key projects
Gas deal supplies energy diversification
Chinese in Iraq feel rising pressure
Decoding China
Japan's ex-PM criticizes militarism
Banks told to act more quickly on home loans
Pope says Israel, Palestine must strive toward peace
Hundreds killed in Boko Haram attack
Yunnan's only panda perking up, thanks to TV, swing
Beijing urges Hanoi to 'stop all disruptions'
Regional body to establish anti-terror unit
Beijing sees tenfold boost in collected pollution fees
49 deals cement partnership
Holiday sees fewer Chinese go to Malaysia
Cats blamed for decline of marsupials
Hunger Games' three-finger salute used to oppose coup in Thailand
Modi to boost ties with China
Brazilian leader backs spending on World Cup
Universities fall short in recruitment of students
Anti-terror campaign launched
Internet a key tool for drug traffickers
Top US school's offer puts young student into spotlight
Scientists finalize test platform for ultra-speed maglev train
Crewmen of S. Korea sunk ferry charged in drownings
McDonald's employees rally against low wages
China won't bow to Japan's demand on 'comfort women'
Nobel winners aim to inspire Chinese youth
Tensions rise as fishing vessel sinks
China and US seek closer military ties
Thai coup leader backed by king, warns citizens
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |