Scientists researching hypnosis have uncovered evidence that counters some of the skeptici

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

Line stemming from the observation that many people who are hypnotizable can be

(5) led to experience compellingly realistic auditory and visual hallucinations.

Noting 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

(10) 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.

(15) 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 eyes covered, their brain activity being monitored under four conditions:

at rest; while hearing an audiotape of a voice, while imagining hearing the voice

(20) 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

(25) 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

(30) 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

(35) 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

(40) 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

A．The high level of realism involved in auditory hallucinations but not in the experience of external sounds

B．The fact that both auditory hallucinations and simple imagining are generated by the research subject

C．The observed similarities between visual and auditory hallucinations in hypnotized subjects

D．The blood flow in areas activated by simple imagining but not by auditory hallucination

E．The tendency of the hallucinating brain to behave much like the brain at rest and unexposed to auditory stimulus