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Dissecting the Neural Circuitry of Fear

al0ha writes "Fear begins in your brain, and it is there — specifically in an almond-shaped structure called the amygdala — that it is controlled, processed, and let out of the gate to kick off the rest of the fear response. In this week's issue of the journal Nature, a research team led by scientists at the California Institute of Technology has taken an important step toward understanding just how this kickoff occurs by beginning to dissect the neural circuitry of fear. In their paper (abstract), these scientists ... describe a microcircuit in the amygdala that controls, or 'gates,' the outflow of fear from that region of the brain. The microcircuit in question, [Professor David J. Anderson] explains, contains two subtypes of neurons that are antagonistic — have opposing functions — and that control the level of fear output from the amygdala by acting like a seesaw. 'Imagine that one end of a seesaw is weighted and normally sits on a garden hose, preventing water — in this analogy, the fear impulse — from flowing through it,' says Anderson. 'When a signal that triggers a fear response arrives, it presses down on the opposite end of the seesaw, lifting the first end off the hose and allowing fear, like water, to flow.' Once the flow of fear has begun, that impulse can be transmitted to other regions of the brain that control fearful behavior, such as freezing in place."

8 of 123 comments (clear)

  1. Now that you know how fear works by MRe_nl · · Score: 5, Funny

    Please put your hand in this little box...

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    "Kill 'em all and let Root sort 'em out"
  2. Remove it! by falldeaf · · Score: 4, Interesting

    I wonder if the repercussions of removing the amygdala completely would be catastrophic to the person. In a society where we don't necessarily have direct predators, would a fearless person be more bold and have less stress? I wouldn't mind a boost in either of those traits. :)

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    1. Re:Remove it! by Anonymous Coward · · Score: 4, Funny

      removing the amygdala completely

      It's not worth it, trust me.

      -River Tam

      PS: Also, I can kill you with my brain.

  3. Fox News. by Xoltri · · Score: 4, Funny

    That's funny, I thought fear response was controlled by Fox News.

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    -Xoltri
  4. Re:Yoda says... by Anonymous Coward · · Score: 5, Funny

    Wasn't Senator Amygdala the reason Anakin fell to the Dark Side?

  5. Re:Now that you know how fear works by Anonymous Coward · · Score: 5, Interesting

    I must not fear.
    Fear is the mind-killer.
    Fear is the little-death that brings total obliteration.
    I will face my fear.
    I will permit it to pass over me and through me.
    And when it has gone past I will turn the inner eye to see its path.
    Where the fear has gone there will be nothing.
    Only I will remain

  6. Re:Now that you know how fear works by circletimessquare · · Score: 5, Insightful

    Fear is good. Fear is healthy. Fear keeps you alive. A person without fear would rapidly become dead, as there would be nothing preventing them from taking crazy risks. And if you say someone can make a rational appraisal of risks, I am telling that a person doing such a rational appraisal will wander into traffic in their fearlessness while they are doing their cognitive calculations.

    When people identify fear as a negative impulse, they are actually complaining about things that stupid people fear, which are usually artificial constructs, and are usually controlled by fearmongering demagogues spreading propaganda for political purposes. Yes, this is wrong, but fear is only a piece of that puzzle, and not even the lynchpin.

    Fear itself is not wrong, only what stupid people fear is wrong. I have fears in my life, and I'm glad I do. It keeps me alive, it even motivates me. It would be a shame to disregard such potent neural circuitry just because of some political hangups that have nothing to do with you.

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  7. Re:Now that you know how fear works by swillden · · Score: 4, Interesting

    Fear itself is not wrong, only what stupid people fear is wrong. I have fears in my life, and I'm glad I do. It keeps me alive, it even motivates me.

    Absolutely. Fear guides our actions in many ways, and generally for the better. Applied properly, it can help us make quick decisions with sufficient accuracy in situations where there simply isn't time to apply rational analysis. The decisions aren't always as good as rational decisions would be, but they're generally not too far off, and often doing nothing is even worse than doing something that isn't quite right.

    For example, I teach concealed weapon permit courses, and one of the major challenges faced by any rational, law-abiding person who decides to carry a deadly weapon is to learn how to decide under what circumstances they should use it. In the course I cover the ins and outs of the law, but there's no way anyone can apply that knowledge in the split second available during a possibly-deadly encounter. It's too complex and too abstract.

    So in addition to the law, I teach people to train themselves to use their fear, to assume that if they draw and fire their gun they will go to prison for it, and so they should only use it in circumstances where they fear the consequences of not shooting even more than that. This "balance of opposing fears" is something that can be done on an emotional level -- with "the gut" --, and it can be done very quickly. Not to mention the fact that the standard of justification in the law is based on the presence of "reasonable fear", so if you're a reasonable person and you have a great fear, then you should be legally justified when the DA and/or jury gets around to weighing your actions against the minutiae of the law.

    Of course, some people are more afraid of prison than of dying, so it might not be a good standard for them.

    (Aside: This being slashdot, I know I'm going to get some responses saying that anyone who wants to carry a gun already has a broken "fear sense", but that's simply untrue. I have taught many, many people and the only ones I've met who decide to carry out of a sense of fear really DO have reason to fear -- mostly women with dangerous and unstable exes. Mostly, people who decide to carry do it more out of a sense of determination that they do not want to be a victim. Not that they think they're likely to be victims, but they see it as a reasonable precaution, much like having a fire extinguisher in their car and house.)

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