Scientists researching hypnosis have uncovered evidence that counters some of the skepticism about the technique. One skeptical

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问题     Scientists researching hypnosis have uncovered evidence that counters some of the skepticism about the technique. One skeptical hypothesis is that hypnosis may be the product of "vivid imagination", a now discredited charge stemming from the observation that many people who are hypnotizable can be led to experience compellingly realistic auditory and visual hallucinations. Nothing that an auditory hallucination and the act of imagining a sound are both self-generated and that, like real hearing, a hallucination is experienced as the product of an external source, Henry Szechtman used PET(positron emission tomography)to image the brain activity of hypnotized subjects invited to imagine a scenario and then experiencing a hallucination. By monitoring regional blood flow in areas activated during both hearing and auditory hallucination but not during simple imagining, the investigators sought to determine where in the brain a hallucinated sound is mistakenly "tagged" as authentic and originating in the outside world.
    Szechtman imaged the brain activity of eight very hypnotizable subjects who had been prescreened for their ability to hallucinate under hypnosis. During the session, the subjects were under hypnosis and lay in the PET scanner with their brain activity being monitored under four conditions: at rest;while hearing an audiotape of a voice, while imagining hearing the voice again;and during the auditory hallucination they experienced after being informed that the tape was playing once more, although it was not. The tests suggested that a region of the brain called the right anterior cingulate cortex was just as active while the volunteers were hallucinating as it was while they were actually hearing the stimulus. In contrast, that brain area remained dormant while the subjects were imagining that they heard the stimulus.
    The second major objection raised by critics argues that hypnosis’ ability to blunt pain results from either simple relaxation or a placebo response. McGlashan established that while hypnosis was only as effective in reducing pain as a sugar pill for poorly hypnotizable people, highly hypnotizable subjects benefited three times more from hypnosis than from the placebo. In response to these successes, Rainville devised experiments to determine which brain structures are involved in pain relief during hypnosis, attempting to locate the brain structures associated with the suffering component of pain, as distinct from its sensory aspects. Using PET, he and other scientists found that hypnosis reduced the activity of the anterior cingulate cortex—an area known to be involved in pain—but did not affect the activity of the somatosensory cortex, where the sensations of pain are processed.
    Despite the value of these findings, the mechanisms underlying hypnotic pain relief are still poorly understood. The model favored by most researchers is that the analgesic effect of hypnosis occurs in higher brain centers than those involved in registering the painful sensation, accounting for the fact that most autonomic responses that routinely accompany pain—such as increased heart rate — are relatively unaffected by hypnotic suggestions of analgesia.
Which of the following best expresses the main idea of the passage?

选项 A、Research has suggested that positron emission tomography will soon answer most skeptical objections to the existence of the phenomenon of hypnosis.
B、Researchers have failed to present incontrovertible evidence that skeptical explanations of the hypnosis phenomenon are unwarranted.
C、Researchers have spent an adequate amount of time allaying skepticism concerning the effects of hypnosis, though more needs to be understood.
D、Researchers have recently made valuable discoveries concerning the potential of hypnosis in creating auditory hallucinations.

答案C

解析 文章主旨题。根据原文,研究人员花了大量的时间和精力研究催眠问题,反驳了开篇提到的怀疑。文章在最后又指出,对于催眠止痛背后的机制我们仍然知之甚少,所以正确答案是C选项。
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