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Your eyes are growing heavy ....

You could say it’s a nightclub hypnotist’s nightmare. He calls a willing victim up to the stage, asks him to stare at the pocket watch, and then informs the audience member that he’s now a chicken.

But instead of clucking, or doing that arm flap thing, the smart-alecky subject winks at the audience and refuses to cooperate. But why are some people tough to hypnotize, while others seem to fall under the spell lickety-split?

David Spiegel, a physician in the department of psychiatry and behavioral sciences at Stanford University, and a team of colleagues, think they’ve discovered an important difference between people who are easy to hypnotize and those who aren’t.

According to the team’s study of 24 individuals, presented in the Archives of General Psychiatry, people with a low barrier to hypnosis have more functional connectivity between two areas of the brain: the left dorsolateral prefrontal cortex -- a region vital for executive functions – and the “salience network” – parts of the brain including the anterior cingulated cortex, amygdala, ventral striatum – that assigns importance to emotional, autonomic and somatic information.

In other words, parts of the brain that are constantly on the lookout for signals, and attaching emotional meaning to the input, and part of our prefrontal cortex that develops “action plans” about how to react to such signals, are communicating with each other more powerfully.  

Spiegel used an example to explain what this means in real life. For example, a high hypnotizable person might sit down in the university library stacks to study, and lose all track of time because he’s so absorbed in the work. Or, when watching a movies, a high hypnotizable person might become so absorbed in it, he forgets it’s even a movie. 

“It’s that when you are tracking something, you’re not worried about tracking something else,” Spiegel explained.   

To figure this out, the researchers used 24 adults, mainly Stanford students, who, using a standard test called the Hypnotic Induction Profile, scored as either high or low hypnotizability.

Both groups were examined in a functional magnetic imaging (fMRI) machine. They were given no specific instructions regarding what to think about while in the machine, a “resting state.” There were no differences in physical brain structure or in the volume of various brain regions.

But there was a difference in function: The brains of people who were “high hypnotizable” showed that the dorsolateral prefrontal cortex was being functionally incorporated into the “salience network.” This didn’t happen in the low hypnotizable group.

“Normally, the dorsolateral prefrontal cortex is thinking, planning, deciding what to do next. And the anterior cingulate cortex is telling you what to be worried about,” Spiegel said. “In high hypnotizable people, these two tend to be functionally connected.”

The fact there wasn’t any difference in brain structure leads Spiegel to suggest that brain signaling chemicals might be responsible for the difference. People have different gene variants, called polymorphisms, that carry instructions for the way dopamine works in the brain. Previous studies have found that some polymorphisms are correlated with hypnotizability, cognitive function, alertness. So Spiegel thinks that’s a likely candidate to explain the difference in function between the two groups.

The study has its limitations, Spiegel admitted, like the low number of subjects, and the fact they weren’t hypnotized while in the fMRI. But the work is important, he said, because hypnosis is now often used for pain relief, to dampen anxiety in cancer patients undergoing treatment, and in psychotherapy. Knowing who’s likely to benefit could go a long way to making it an even more valuable tool.

Brian Alexander (www.BrianRAlexander.com) is co-author, with Larry Young Ph.D., of "The Chemistry Between Us: Love, Sex and the Science of Attraction," (www.TheChemistryBetweenUs.com), now on sale.

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By Wayne Parry
LiveScience 

The true nature of hypnosis has eluded scientists. It's clear people can be hypnotized, but it's not clear how this happens. New research offers a clue.

By recording the eye movements of a hypnotized woman, and comparing them with those of nonhypnotized people, researchers say they have found evidence that hypnosis involves a special mental state, fundamentally different from normal consciousness.

First some basics: When under hypnosis, a person becomes more capable of hallucinationand susceptible to suggestions, perhaps intended to help him or her stop craving cigarettes, say, or prompt him or her to hear music that isn't actually playing. If no suggestions are given, a hypnotized person will sit still and his or her mind will enter a calm state, like that associated with meditation. After a session ends, the person doesn't remember it, according to study researcher Sakari Kallio, an associate professor at the University of Skövde in Sweden and University of Turku in Finland.  

Some believe these things happen because of a change in brain activity that alters a person's state of consciousness. Another camp believes that under hypnosis, the brain functions just as it would at any other time while awake, and that other, normal processes — like an active imagination — are at work.

Solving this debate by measuring brain activity is dicey, since our brain's electrical activity can vary significantly from moment to moment during its normal state. But the identification of a behavior associated with an altered state of consciousness — something no one could fake — would go a long way to supporting the idea that hypnosis involves a change in consciousness.

And that's exactly what a team of researchers says they have found, by looking at the eye movements of an easily hypnotized Finnish woman.

This woman, identified in the study published in the journal PLoS ONE on Oct. 24 only by her initials TS-H, is 43, an office worker, right-handed, and "as normal as can be," said Kallio, the lead study researcher. TS-H has no history of any neurological or psychiatric illnesses and a normal psychological profile, he and colleagues wrote. [10 Controversial Psychiatric Disorders]

She is, however, also unusually responsive to hypnosis. Kallio said that while TS-H was hypnotized, he could easily induce her to see or hear things that weren't present, and that she forgot the session when the hypnosis ended.

Using three different visual tests, they found that while hypnotized, her pupils became smaller and she blinked more slowly and less frequently — about 10 times less often –- than normally. When moving her gaze to a new point on a screen, her eyes "crept" along, moving in shorter jumps, when normally they would have moved swiftly. And, when watching the middle point of a field of moving bars, her eyes made fewer, smaller, slower movements back and forth.

Because people have little conscious control over these kinds of movements, it is unlikely someone could fake them, according to Kallio.

He and colleagues gave 14 nonhypnotized volunteers the same tasks, and asked the volunteers to perform them naturally, and to try to mimic hypnotized eye movements. While in some instances, such as with blinking, the nonhypnotized volunteers did well, overall, none came close to matching the hypnotized eye movements.

The results don’t come without precedence; a change in the eyes, or a unique sort of stare, has long been associated with hypnosis.

Measurements of electrical activity in TS-H's hypnotized brain taken in separate research also indicate something was going on. In three different experiments, researchers found changes they would not expect in a normal brain, according to Kallio.

In one study, the connections between the frontal area and the rest of the brain diminished dramatically, which typically happens during sleep. Then hypnosis also made her brain's right hemisphere more dominant, although this finding is difficult to interpret, Kallio told LiveScience in an email.

While a bit trickier to interpret, brain measurements further support the idea that something unique happens in TS-H's brain during hypnosis, according to Kallio.

Have you ever been hypnotized? Leave a comment telling us about the experience.

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