What’s the first thing you do when you burn or cut one of your hands? You might think the answer is that you put it under a fauc

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问题     What’s the first thing you do when you burn or cut one of your hands? You might think the answer is that you put it under a faucet or wrap a towel around it. But that’s actually not the first thing you do. The first thing is reflexive, unthinking—something your ancestors could have done in the wild: you grasp the hurt hand with the other one. We have known at least since the 1960s that this kind of self-touch actually reduces pain. If you try to keep your other hand away, you will hurt a lot more. It’s not just the pressure you apply. Pain is reduced far more when it’s your own hand, not anyone else’s.
    Now a new study shows that self-touch also minimizes more complex kinds of pain. In their experiment, the authors, a team led by Marjolein Kammers, used self-touch to reduce a complicated physical sensation called central pain.
    Central pain is also the major player in the carnival-like experiment called the thermal grill illusion. In the thermal grill illusion, you are made to touch a very warm object—say, a heated-but-not-scorching grill— and then, immediately afterward, a cool object such as a room-temperature grill. Quite reliably, your brain will fool you into believing the second object is extremely hot, even though nothing has happened to your flesh. The first grill wasn’t hot enough to burn, and the second is actually cool. But your brain is confused: that’s central pain. Even though the thermal grill illusion was first written about in the 19th century, neurologists have never been able to understand precisely how it works and whether it could be used in treating pain.
    Kammers’ team replicated the thermal grill illusion using water. Her participants immersed their index and ring fingers in 39-degree-Celsius water. Their middle fingers were put in 14-degree-Celsius water. In this condition, the two middle fingers felt much hotter than they did when the four index and ring fingers were immersed in neutral water.
    But Kammers added a new twist to the thermal grill illusion: after their fingers felt the thermal-grill sensation, she asked participants to press the fingers of their two hands together. When they did so, their middle fingers hurt a lot less than when they touched someone else’s hand.
    Kammers and her team struggled to explain the findings. Something is surely happening in a brain region called the somatosensory cortex, but psychological responses are also involved. It’s all a bit vague. Still, the findings suggest that the body and brain have instinctive ways of healing that we could come to understand one day and then magnify.  
Which of the following is TRUE of central pain?

选项 A、It’s caused by the confusion of the brain.
B、It usually happens in some experiments.
C、It can be verified by the thermal grill illusion.
D、It can be felt when you touch cool objects.

答案C

解析 细节题。本题解答应首先定位至第二段。根据这个过渡段所显示的思路,作者欲在下一段说明什么是中枢性疼痛。但他并没有直接给出定义,而是通过例举一个特殊的实验来进行说明。由此可见,这个实验能够对中枢性疼痛进行验证和研究,故[C]为答案。四个选项中,最易排除[B]项。该项混淆了实验与研究对象的关系,中枢性疼痛是实验的研究对象,而不是实验所引发的现象。[D]项断章取义,热烤错觉实验中,实验对象是先接触了较热的物体后再接触凉物体才感到中枢性疼痛的,只取其中一个过程是不完整的说法。[A]项误解了实验现象和对象的关系,实验过程引起了大脑的混乱,实验对象因此感受到中枢性疼痛。这只是为了显示心理作用对身体感觉的影响,而不能就此断定中枢性疼痛的病因就是大脑混乱。
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