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Medicine Science

Dissecting the Neural Circuitry of Fear 123

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."
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Dissecting the Neural Circuitry of Fear

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  • Remove it! (Score:4, Interesting)

    by falldeaf ( 968657 ) <falldeaf@gmail. c o m> on Friday November 12, 2010 @12:41PM (#34207768) Homepage
    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. :)
  • Autism? (Score:4, Interesting)

    by AltGrendel ( 175092 ) <ag-slashdot.exit0@us> on Friday November 12, 2010 @12:48PM (#34207836) Homepage
    I wonder if they'll try the same techniques to study Autism?
  • Re:Remove it! (Score:3, Interesting)

    by Jeremiah Cornelius ( 137 ) on Friday November 12, 2010 @12:50PM (#34207864) Homepage Journal


    They just want raw, killer soldiers - who won't come back with either PTSD or a human soul.

    This is the kind of research that begins looking lie rational inquiry into the determining mechanisms of everyday psychology, and ends in horrors.

  • by Anonymous Coward on Friday November 12, 2010 @12:52PM (#34207896)

    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

  • worrying (Score:3, Interesting)

    by mlong ( 160620 ) on Friday November 12, 2010 @12:55PM (#34207930)
    I wonder how this applies to worriers? Like the people afraid of every possible thing that could wrong. And what part of the brain controls more general fears like the fear of death?
  • Re:worrying (Score:4, Interesting)

    by Monkeedude1212 ( 1560403 ) on Friday November 12, 2010 @01:05PM (#34208064) Journal

    Couldn't that be described as a "chemical inbalance" in the brain? As in, the the see-saw isn't pinching the hose enough to turn it off?

  • Re:Remove it! (Score:3, Interesting)

    by Monkeedude1212 ( 1560403 ) on Friday November 12, 2010 @01:11PM (#34208130) Journal

    I agree with your point - even without fear you would still have your rational logic (supposedly, we don't know exactly what would happen when you remove this chunk of the brain).

    But assuming that you DO still have logical reasoning and you think "It's in my best interest to NOT rob a bank" - at what point do you then get a benefit by removing the gland? Essentially fear is designed to help your survival - it's not always right - like the deer in headlights freezing when something is heading your way, but that's essentially your body saying "Something you are doing something wrong, STOP" but usually by then its too late. Taking it away doesn't seem to have any real benefits - I don't see how it would reduce stress (if you are still tasked with making difficult decisions) since you don't always come across life-or-death situations everyday.

    Like someone else posted, there are horror movies, roller coasters, video games, etc, a whole bunch of things designed you give you the fear-reaction in a safe environment. By removing that ability you're essentially removing some of the things you can enjoy in life.

  • Re:worrying (Score:3, Interesting)

    by kent_eh ( 543303 ) on Friday November 12, 2010 @01:27PM (#34208340)
    I'm more interested in what implications this has into dealing with paranoia (as in full-on psychiatric disorder, not the popular usage of the word) .
    I have seen what paranoid delusions can do to a person, and it ain't pretty.
  • by swillden ( 191260 ) <> on Friday November 12, 2010 @02:36PM (#34209218) Homepage Journal

    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.)

  • Re:worrying (Score:3, Interesting)

    by butalearner ( 1235200 ) on Friday November 12, 2010 @03:11PM (#34209614)

    I'm more interested in what implications this has into dealing with paranoia (as in full-on psychiatric disorder, not the popular usage of the word) . I have seen what paranoid delusions can do to a person, and it ain't pretty.

    That is an interesting question. I must be a bad person, but my first thought was the opposite of most commenters:

    Can we hook up electrodes and magnify fear, say, for the purposes of obtaining a confession? It's a slippery slope I admit, but I would guess that the amount of stimulation is important. Especially if you can inflict a major mental disorder on the suspect.

    If this is blatant Geneva Convention-breaking torture, I apologize for my ignorance; the UN definition is so vague you could consider imprisonment a type of torture. I figure it seems far more "humane" than waterboarding at least.

  • by radtea ( 464814 ) on Friday November 12, 2010 @03:16PM (#34209684)

    Fear is good. Fear is healthy. Fear keeps you alive.

    Which fear is that?

    Your post, and the others here praising fear, are excellent examples of innumeracy: you treat the world as it existed in real binary categorical terms "fearful" and "fearless".

    The real world is a bit more floating point than that.

    I suffer from a deficit of physical fear, yet I am still manifestly alive.

    I routinely judge things based on rational probabilities. I once walked out into a fairly busy highway to remove some debris that had forced me to swerve. I could see from basic kinematics I had plenty of time to get out there, get the thing (a large piece of somebody's bumper, as it turned out) and get back without significant risk. So I did so. The person I was with was beside herself with fear on my behalf.

    Incidents like this eventually convinced me that I was physiologically defficient in this regard, and made me more aware of the importance of rational risk-estimation in my life. But I am now nearing my second half-century, and still not dead.

    The interesting question to me is: would most people be better off with LESS fear in their lives, or MORE?

    Today, I'd argue strongly for less, across the board, so that fear was just one of many mild emotional impulses that people could take into account when choosing actions, rather than an apparently unanswerable motivation to do all manner of stupid things.

  • by eggstasy ( 458692 ) on Friday November 12, 2010 @04:38PM (#34210616) Journal

    You can probably get by without fear in a nanny state ruled by the fearful masses, where everything has to be made perfectly safe, but try doing that in the jungles of your ancestors, where danger awaited around every corner...

Logic is the chastity belt of the mind!