Recognising hypnosis

Hypnosis is still seen, by many, with suspicion. Too much reporting about those who go around and tricking you of your ATM machine card or even used hypnosis for bank robberies.

Now, hypnosis gains new respect. In medicine and in psychological treatments.

The linked article is lengthy, but worthwhile a read:


At the snap of my fingers
December 3, 2005Page 1 of 2
The science - or art - of hypnosis is gaining new respect from scientists, writes Sandra Blakeslee.

Hypnosis, with its long and chequered history in medicine and entertainment, is receiving some respect from neuroscientists.

Recent brain studies of people who are susceptible to suggestion indicate that when they act on the suggestions their brains show profound changes in how they process information. The suggestions, researchers report, change what people see, hear, feel and believe to be true.

The experiments, which used brain imaging, found that people who were hypnotised "saw" colours where there were none. Others lost the ability to make simple decisions. Some people looked at common English words and thought they were gibberish.

"The idea that perceptions can be manipulated by expectations" is fundamental to the study of cognition, said Michael Posner, an emeritus professor of neuroscience at the University of Oregon and expert on attention. "But now we're really getting at the mechanisms."

Even with little understanding of how it works, hypnosis has been used in medicine since the 1950s to treat pain and, more recently, as a treatment for depression, trauma, irritable bowel syndrome and eating disorders.

There is, however, still disagreement about what exactly the hypnotic state is, or whether it is anything more than an effort to please the hypnotist or a natural form of extreme concentration where people become oblivious to surroundings.

Hypnosis had a false start in the 18th century when a German physician, Dr Franz Mesmer, devised a miraculous cure for people suffering unexplained medical problems. Amid dim lights and ethereal music played on a glass harmonica, he infused them with an invisible "magnetic fluid" that only he was able to muster. Thus mesmerised, clients were cured. Although Mesmer was eventually discredited, he was the first to show the mind could be manipulated by suggestion to affect the body, historians say. This central finding was resurrected by DrJames Braid, an English ophthalmologist who in 1842 coined the word "hypnosis" after the Greek word for sleep.

Braid reportedly put people into trances by staring at them intently, but he did not have a clue as to how it worked. In this vacuum, hypnosis was adopted by spiritualists and stage magicians who used dangling gold watches to induce hypnotic states in volunteers from the audience.
In medical hands, hypnosis was no laughing matter. In the 19th century, physicians in India successfully used hypnosis as anesthesia, even for limb amputations. The practice fell from favour when ether was discovered.

Now, Posner and others say, research on hypnosis and suggestion is providing a new view into the cogs and wheels of normal brain function.

One area that it may have illuminated is the processing of sensory data. Information from the eyes, ears and body is carried to primary sensory regions in the brain. From there, it is carried to so-called higher regions where interpretation occurs.

For example, photons bouncing off a flower first reach the eye, where they are turned into a pattern that is sent to the primary visual cortex. There, the rough shape of the flower is recognised. The pattern is next sent to a higher - in terms of function - region, where colour is recognised, and then to a higher region, where the flower's identity is encoded along with other knowledge about the particular bloom.

The same processing stream, from lower to higher regions, exists for sounds, touch and other sensory information. Researchers call this direction of flow "feedforward". As raw sensory data is carried to a part of the brain that creates a comprehensible, conscious impression, the data is moving from bottom to top.

Bundles of nerve cells dedicated to each sense carry sensory information. The surprise is the amount of traffic the other way, from top to bottom. There are 10 times as many nerve fibres carrying information down as there are carrying it up. These extensive feedback circuits mean that consciousness, what people see, hear, feel and believe, is based on what neuroscientists call "top down processing."

What you see is not always what you get, because what you see depends on a framework built by experience that stands ready to interpret the raw information - as a flower or a hammer or a face.

The top-down structure explains a lot. If the construction of reality has so much top-down processing, that would make sense of the powers of placebos (a sugar pill will make you feel better), nocebos (a witch doctor will make you ill), talk therapy and meditation. If the top is convinced, the bottom level of data will be overruled. This brain structure would also explain hypnosis, which is all about creating such formidable top-down processing that suggestions overcome reality.

According to decades of research, 10 to 15 per cent of adults are highly hypnotisable, said Dr David Spiegel, a psychiatrist at Stanford who studies the clinical uses of hypnosis. Up to age 12, however, before top-down circuits mature, 80 to 85 per cent of children are highly hypnotisable. One adult in five is flat out resistant to hypnosis, Spiegel said. The rest are in between, he said.

A number of recent studies of brain imaging point to top-down brain mechanisms under the influence of suggestion. Highly hypnotisable people were able to "drain" colour from a colorful abstract drawing or "add" colour to the same drawing rendered in grey tones. In each case, the parts of their brains involved in colour perception were differently activated.

Brain scans show the control mechanisms for deciding what to do in the face of conflict become uncoupled when people are hypnotised.

Top-down processes override sensory, or bottom-up information, says Dr Stephen Kosslyn, a neuroscientist at Harvard. People think sights, sounds and touch from the outside world constitute reality. But the brain constructs what it perceives based on past experience, Kosslyn says.

Most of the time bottom-up information matches top-down expectation, Spiegel says. But hypnosis is interesting because it creates a mismatch. "We imagine something different, so it is different," he said.

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