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This Is Your Brain Under Hypnosis

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    NHNE News List Current Members: 1386 Subscribe/unsubscribe/archive info at the bottom of this message. ... THIS IS YOUR BRAIN UNDER HYPNOSIS By Sandra
    Message 1 of 1 , Nov 23 11:17 AM
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      By Sandra Blakeslee
      New York Times
      November 22, 2005


      Hypnosis, with its long and checkered history in medicine and entertainment,
      is receiving some new 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, literally change what
      people see, hear, feel and believe to be true.

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

      "The idea that perceptions can be manipulated by expectations" is
      fundamental to the study of cognition, said Michael I. 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 1950's to treat pain and, more recently, as a treatment
      for anxiety, depression, trauma, irritable bowel syndrome and eating

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

      Hypnosis had a false start in the 18th century when a German physician, Dr.
      Franz Mesmer, devised a miraculous cure for people suffering all manner of
      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 mesmerized, clients were cured.

      Although Dr. Mesmer was eventually discredited, he was the first person to
      show that the mind could be manipulated by suggestion to affect the body,
      historians say. This central finding was resurrected by Dr. James 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, and make them
      dance, sing or pretend to be someone else, only to awaken at a hand clap and
      laughter from the crowd.

      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 favor only when ether was discovered.

      Now, Dr. Posner and others said, new 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 recognized. The pattern is next sent to a
      higher -- in terms of function -- region, where color is recognized, 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,
      called feedback. There are 10 times as many nerve fibers 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

      According to decades of research, 10 to 15 percent of adults are highly
      hypnotizable, 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 percent of children are highly hypnotizable.

      One adult in five is flat out resistant to hypnosis, Dr. Spiegel said. The
      rest are in between, he said.

      In some of the most recent work, Dr. Amir Raz, an assistant professor of
      clinical neuroscience at Columbia, chose to study highly hypnotizable people
      with the help of a standard psychological test that probes conflict in the
      brain. As a professional magician who became a scientist to understand
      better the slippery nature of attention, Dr. Raz said that he "wanted to do
      something really impressive" that other neuroscientists could not ignore.

      The probe, called the Stroop test, presents words in block letters in the
      colors red, blue, green and yellow. The subject has to press a button
      identifying the color of the letters. The difficulty is that sometimes the
      word RED is colored green. Or the word YELLOW is colored blue.

      For people who are literate, reading is so deeply ingrained that it
      invariably takes them a little bit longer to override the automatic reading
      of a word like RED and press a button that says green. This is called the
      Stroop effect.

      Sixteen people, half highly hypnotizable and half resistant, went into Dr.
      Raz's lab after having been covertly tested for hypnotizability. The purpose
      of the study, they were told, was to investigate the effects of suggestion
      on cognitive performance. After each person underwent a hypnotic induction,
      Dr. Raz said:

      "Very soon you will be playing a computer game inside a brain scanner. Every
      time you hear my voice over the intercom, you will immediately realize that
      meaningless symbols are going to appear in the middle of the screen. They
      will feel like characters in a foreign language that you do not know, and
      you will not attempt to attribute any meaning to them.

      "This gibberish will be printed in one of four ink colors: red, blue, green
      or yellow. Although you will only attend to color, you will see all the
      scrambled signs crisply. Your job is to quickly and accurately depress the
      key that corresponds to the color shown. You can play this game
      effortlessly. As soon as the scanning noise stops, you will relax back to
      your regular reading self."

      Dr. Raz then ended the hypnosis session, leaving each person with what is
      called a posthypnotic suggestion, an instruction to carry out an action
      while not hypnotized.

      Days later, the subjects entered the brain scanner.

      In highly hypnotizables, when Dr. Raz's instructions came over the intercom,
      the Stroop effect was obliterated, he said. The subjects saw English words
      as gibberish and named colors instantly. But for those who were resistant to
      hypnosis, the Stroop effect prevailed, rendering them significantly slower
      in naming the colors.

      When the brain scans of the two groups were compared, a distinct pattern
      appeared. Among the hypnotizables, Dr. Raz said, the visual area of the
      brain that usually decodes written words did not become active. And a region
      in the front of the brain that usually detects conflict was similarly

      Top-down processes overrode brain circuits devoted to reading and detecting
      conflict, Dr. Raz said, although he did not know exactly how that happened.
      Those results appeared in July in The Proceedings of the National Academy of

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

      Brain scans show that the control mechanisms for deciding what to do in the
      face of conflict become uncoupled when people are hypnotized. Top-down
      processes override sensory, or bottom-up information, said Dr. Stephen M.
      Kosslyn, a neuroscientist at Harvard. People think that sights, sounds and
      touch from the outside world constitute reality. But the brain constructs
      what it perceives based on past experience, Dr. Kosslyn said.

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


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