[Paleopsych] NYT: Cells That Read Minds

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Cells That Read Minds
http://www.nytimes.com/2006/01/10/science/10mirr.html

[This is a particularly important article, for it connects social learning 
with the brain. File it under the G in GRIN: genetics, robotics, 
information, nanotech.]

    By SANDRA BLAKESLEE

    On a hot summer day 15 years ago in Parma, Italy, a monkey sat in a
    special laboratory chair waiting for researchers to return from lunch.
    Thin wires had been implanted in the region of its brain involved in
    planning and carrying out movements.

    Every time the monkey grasped and moved an object, some cells in that
    brain region would fire, and a monitor would register a sound:
    brrrrrip, brrrrrip, brrrrrip.

    A graduate student entered the lab with an ice cream cone in his hand.
    The monkey stared at him. Then, something amazing happened: when the
    student raised the cone to his lips, the monitor sounded - brrrrrip,
    brrrrrip, brrrrrip - even though the monkey had not moved but had
    simply observed the student grasping the cone and moving it to his
    mouth.

    The researchers, led by Giacomo Rizzolatti, a neuroscientist at the
    University of Parma, had earlier noticed the same strange phenomenon
    with peanuts. The same brain cells fired when the monkey watched
    humans or other monkeys bring peanuts to their mouths as when the
    monkey itself brought a peanut to its mouth.

    Later, the scientists found cells that fired when the monkey broke
    open a peanut or heard someone break a peanut. The same thing happened
    with bananas, raisins and all kinds of other objects.

    "It took us several years to believe what we were seeing," Dr.
    Rizzolatti said in a recent interview. The monkey brain contains a
    special class of cells, called mirror neurons, that fire when the
    animal sees or hears an action and when the animal carries out the
    same action on its own.

    But if the findings, published in 1996, surprised most scientists,
    recent research has left them flabbergasted. Humans, it turns out,
    have mirror neurons that are far smarter, more flexible and more
    highly evolved than any of those found in monkeys, a fact that
    scientists say reflects the evolution of humans' sophisticated social
    abilities.

    The human brain has multiple mirror neuron systems that specialize in
    carrying out and understanding not just the actions of others but
    their intentions, the social meaning of their behavior and their
    emotions.

    "We are exquisitely social creatures," Dr. Rizzolatti said. "Our
    survival depends on understanding the actions, intentions and emotions
    of others."

    He continued, "Mirror neurons allow us to grasp the minds of others
    not through conceptual reasoning but through direct simulation. By
    feeling, not by thinking."

    The discovery is shaking up numerous scientific disciplines, shifting
    the understanding of culture, empathy, philosophy, language,
    imitation, autism and psychotherapy.

    Everyday experiences are also being viewed in a new light. Mirror
    neurons reveal how children learn, why people respond to certain types
    of sports, dance, music and art, why watching media violence may be
    harmful and why many men like pornography.

    How can a single mirror neuron or system of mirror neurons be so
    incredibly smart?

    Most nerve cells in the brain are comparatively pedestrian. Many
    specialize in detecting ordinary features of the outside world. Some
    fire when they encounter a horizontal line while others are dedicated
    to vertical lines. Others detect a single frequency of sound or a
    direction of movement.

    Moving to higher levels of the brain, scientists find groups of
    neurons that detect far more complex features like faces, hands or
    expressive body language. Still other neurons help the body plan
    movements and assume complex postures.

    Mirror neurons make these complex cells look like numbskulls. Found in
    several areas of the brain - including the premotor cortex, the
    posterior parietal lobe, the superior temporal sulcus and the insula -
    they fire in response to chains of actions linked to intentions.

    Studies show that some mirror neurons fire when a person reaches for a
    glass or watches someone else reach for a glass; others fire when the
    person puts the glass down and still others fire when the person
    reaches for a toothbrush and so on. They respond when someone kicks a
    ball, sees a ball being kicked, hears a ball being kicked and says or
    hears the word "kick."

    "When you see me perform an action - such as picking up a baseball -
    you automatically simulate the action in your own brain," said Dr.
    Marco Iacoboni, a neuroscientist at the University of California, Los
    Angeles, who studies mirror neurons. "Circuits in your brain, which we
    do not yet entirely understand, inhibit you from moving while you
    simulate," he said. "But you understand my action because you have in
    your brain a template for that action based on your own movements.

    "When you see me pull my arm back, as if to throw the ball, you also
    have in your brain a copy of what I am doing and it helps you
    understand my goal. Because of mirror neurons, you can read my
    intentions. You know what I am going to do next."

    He continued: "And if you see me choke up, in emotional distress from
    striking out at home plate, mirror neurons in your brain simulate my
    distress. You automatically have empathy for me. You know how I feel
    because you literally feel what I am feeling."

    Mirror neurons seem to analyzed scenes and to read minds. If you see
    someone reach toward a bookshelf and his hand is out of sight, you
    have little doubt that he is going to pick up a book because your
    mirror neurons tell you so.

    In a study published in March 2005 in Public Library of Science, Dr.
    Iacoboni and his colleagues reported that mirror neurons could discern
    if another person who was picking up a cup of tea planned to drink
    from it or clear it from the table. "Mirror neurons provide a powerful
    biological foundation for the evolution of culture," said Patricia
    Greenfield, a psychologist at the U.C.L.A. who studies human
    development.

    Until now, scholars have treated culture as fundamentally separate
    from biology, she said. "But now we see that mirror neurons absorb
    culture directly, with each generation teaching the next by social
    sharing, imitation and observation."

    Other animals - monkeys, probably apes and possibly elephants,
    dolphins and dogs - have rudimentary mirror neurons, several mirror
    neuron experts said. But humans, with their huge working memory, carry
    out far more sophisticated imitations.

    Language is based on mirror neurons, according to Michael Arbib, a
    neuroscientist at the University of Southern California. One such
    system, found in the front of the brain, contains overlapping
    circuitry for spoken language and sign language.

    In an article published in Trends in Neuroscience in March 1998, Dr.
    Arbib described how complex hand gestures and the complex tongue and
    lip movements used in making sentences use the same machinery. Autism,
    some researchers believe, may involve broken mirror neurons. A study
    published in the Jan. 6 issue of Nature Neuroscience by Mirella
    Dapretto, a neuroscientist at U.C.L.A., found that while many people
    with autism can identify an emotional expression, like sadness, on
    another person's face, or imitate sad looks with their own faces, they
    do not feel the emotional significance of the imitated emotion. From
    observing other people, they do not know what it feels like to be sad,
    angry, disgusted or surprised.

    Mirror neurons provide clues to how children learn: they kick in at
    birth. Dr. Andrew Meltzoff at the University of Washington has
    published studies showing that infants a few minutes old will stick
    out their tongues at adults doing the same thing. More than other
    primates, human children are hard-wired for imitation, he said, their
    mirror neurons involved in observing what others do and practicing
    doing the same things.

    Still, there is one caveat, Dr. Iacoboni said. Mirror neurons work
    best in real life, when people are face to face. Virtual reality and
    videos are shadowy substitutes.

    Nevertheless, a study in the January 2006 issue of Media Psychology
    found that when children watched violent television programs, mirror
    neurons, as well as several brain regions involved in aggression were
    activated, increasing the probability that the children would behave
    violently.

    The ability to share the emotions of others appears to be intimately
    linked to the functioning of mirror neurons, said Dr. Christian
    Keysers, who studies the neural basis of empathy at the University of
    Groningen in the Netherlands and who has published several recent
    articles on the topic in Neuron.

    When you see someone touched in a painful way, your own pain areas are
    activated, he said. When you see a spider crawl up someone's leg, you
    feel a creepy sensation because your mirror neurons are firing.

    People who rank high on a scale measuring empathy have particularly
    active mirror neurons systems, Dr. Keysers said.

    Social emotions like guilt, shame, pride, embarrassment, disgust and
    lust are based on a uniquely human mirror neuron system found in a
    part of the brain called the insula, Dr. Keysers said. In a study not
    yet published, he found that when people watched a hand go forward to
    caress someone and then saw another hand push it away rudely, the
    insula registered the social pain of rejection. Humiliation appears to
    be mapped in the brain by the same mechanisms that encode real
    physical pain, he said.

    Psychotherapists are understandably enthralled by the discovery of
    mirror neurons, said Dr. Daniel Siegel, the director of the Center for
    Human Development in Los Angeles and the author of "Parenting From the
    Inside Out," because they provide a possible neurobiological basis for
    the psychological mechanisms known as transference and
    countertransference.

    In transference, clients "transfer" feelings about important figures
    in their lives onto a therapist. Similarly, in countertransference, a
    therapist's reactions to a client are shaped by the therapist's own
    earlier relationships.

    Therapists can use their own mirror system to understand a client's
    problems and to generate empathy, he said. And they can help clients
    understand that many of their experiences stem from what other people
    have said or done to them in the past.

    Art exploits mirror neurons, said Dr. Vittorio Gallese, a
    neuroscientist at Parma University. When you see the Baroque sculptor
    Gian Lorenzo Bernini's hand of divinity grasping marble, you see the
    hand as if it were grasping flesh, he said. Experiments show that when
    you read a novel, you memorize positions of objects from the
    narrator's point of view.

    Professional athletes and coaches, who often use mental practice and
    imagery, have long exploited the brain's mirror properties perhaps
    without knowing their biological basis, Dr. Iacoboni said. Observation
    directly improves muscle performance via mirror neurons.

    Similarly, millions of fans who watch their favorite sports on
    television are hooked by mirror neuron activation. In someone who has
    never played a sport - say tennis - the mirror neurons involved in
    running, swaying and swinging the arms will be activated, Dr. Iacoboni
    said.

    But in someone who plays tennis, the mirror systems will be highly
    activated when an overhead smash is observed. Watching a game, that
    person will be better able to predict what will happen next, he said.

    In yet another realm, mirror neurons are powerfully activated by
    pornography, several scientists said. For example, when a man watches
    another man have sexual intercourse with a woman, the observer's
    mirror neurons spring into action. The vicarious thrill of watching
    sex, it turns out, is not so vicarious after all.