The voicemail rant. The overheard insult. The lonely moral slip when your chips were down.

Despite their sting, these unkind memories eventually slacken their grip. We manage, move on, shrug it off, and go about the business of filling our heads with thoughts of a better tomorrow.

But for war veterans and victims of violent crime, the persistence of traumatic memories can mean a life of disability. Even when emotional demons are quieted with therapy or drugs, they are prone to return. A whispered reminder in an unfamiliar setting is sometimes all it takes.

Frustrated with these grim facts, scientists have been looking for biologically based therapies that may some day help troubled minds forget debilitating fears. The most recent of these studies, by Drs. Roger Clem and Richard Huganir at Johns Hopkins, gives a spectacularly detailed view of how fear is learned, and points out fear’s Achilles Heel. The very molecular machinery that implants fear in the brain may also hold the key to its undoing.

We already understand a good deal about how specific fears come to be thanks to classical neuroscience experiments, many done by Joseph LeDoux and his colleagues at New York University. Fear lives in a small almond-shaped pair of brain structures, called the amgydalae, that control your body’s panic buttons. Each amygdala receives two basic kinds of inputs: streaming images from our senses, as well as incoming alerts conveying threats, danger, or pain. When one of these alert signals – say the pain of a shock or cut – is detected together with a sensory image (such as a particular face or the sound of a gunshot), neurons in the amygdala take notice.

More specifically, amygdala neurons undergo specific chemical and structural changes that form an imprint, or memory, of the sensory image that accompanies a particular threat. In neuroscience lingo, the sensory input is “potentiated.” In plain language: the previously unremarkable mugger’s face now evokes terror.

But how do we unlearn a traumatic memory that’s become dysfunctional? On these questions, we’re more in the dark. The good news is that after they’re formed, fear memories are attentively curated by a host of brain enzymes and proteins that can muffle, modify, and even possibly remove fear. The bad news is that we don’t know which curator handles fear removal.

This is what Clem and Huganir set out to discover. Their first step was to implant fear memories in mice by training them to associate a tone with an electrical shock. After pairing tones and shocks for a few trials, the mice came to respond fearfully – by freezing in place – to the tones alone. As shown before, these behavioral changes were accompanied by long-lasting increases in the strength of sensory input to the amygdala.

So far, this was unsurprising. But Clem and Huganir were just getting started. After finding fear-related changes in amygdala circuits, the scientists went in for a closer and longer look. Their observations paid off with a puzzle. Although the strengthened inputs remained stable and steady for days after fear was learned, amygdala neurons underwent a major molecular overhaul during that time. Glutamate receptors – the main chemical sensors that detect messages sent from neuron to neuron – were being continuously added and removed from the neurons’ surfaces.

This adding and removal of glutamate receptors is not in itself unusual. In fact, it’s one of the main ways that neurons change their connection strength. Pack more receptors into a small area, and a neuron can more sensitively sniff out its inputs; reduced to chemistry, this is what a memory is. What Clem and Huganir found, though, was that amygdala cells swapped one kind of glutamate receptor for another with nearly identical function. It was an exchange that seemed to go nowhere.

14 Comments

1. 1. nealbrock 03:11 PM 12/14/10

   My mother drowned as a child. She obviously was revived, but, as she recalls,was immediately forced to go back in the water. She was told that by forcing her to do this she would not have a fear of water. She never developed a fear of water. Fascinating article.

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2. 2. allicat4u2 06:55 PM 12/14/10

   If I am understanding my brain correctly...long term memory and the amygdala are two different entities. With this said...like the above article...YES, you can overcome fears by "Jumping back in." However, with traumatic experiences, maybe depending on the length of such as in domestic abuses or war, the circumstances become habitual or rather get locked into long term memory which means that although you might take away the fear from the amygdala, you will not remove it's existence in long term memory...I might say that i believe I am a perfect example. I have removed fears from happenings...I do not experience anxieties etc., during the day. However, at night, I bite down on my teeth so hard from the stressors of having lived through strife, that most nights I get no "Real," sleep. I do not think you can ERASE the pains of war or abuses. My experience tells me it is in a different part of the brain and lies dormant until other stressors REignite the memories. My amygdala is of the correct size...I have "Manually," healed myself...but yet, I am NOT healed. So although ONE incident may be erased, I highly doubt that a solider coming back from war can be helped...you would have to be with him on that battle field every ten minutes...so how does this help? I would concentrate on long term memory processes...that is the core of remembering.

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3. 3. jack.123 08:59 PM 12/14/10

   Although a disability for many,both fear and pain have saved life on more than one occasion.

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4. 4. Razza 12:58 AM 12/15/10

   AMYGDALA/HIPPOCAMPUS SECRETS
   
   I tried to tell La Doux the answer to this riddle ten years ago but the arrogant jerk didn't want to listen, I tried to tell Goleman, but he was also too arrogant to listen to anything outside his myopic view of the world of fear. So I eventually gave up trying to convince the orthodox coterie of something outside their tunnel vision.
   
   I wonder how many lives could have been saved from suicide if they had taken what I had/have to say seriously.
   
   Here's a clue. These neuroscience clowns see everything as an object, well here's some news, the mind might be made up of objective matter, but the concepts within that matter are subjective and can only be known to the experiencer.
   
   Oh why bother wasting any more of my time with the orthodoxy, when they have such a hate for heretics, you can read about them all through history.
   
   I'll just keep on creating a parallel path into what will be the future of emotional health.
   
   If you want more info, you can email me at namyar777 at hotmail dot com You'll be amazed at how simple the answer is.

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5. 5. iJonnyV 01:24 AM 12/15/10

   I'm not a science expert or anything. I am just simply baffled by a few things I speculated in my child hood. I'm not very religious. I am still searching for answers.
   Growing up my parents were creditable christian counselors for various situations. Their method for curing ones past, problems, addiction, etc, was they would break the patient down and re-building them with a christian belief system. Their theory was they were refilling their hole with God.
   Is there any truth or relevance to this? Even if you re-filled them with something else? I guess what i'm asking is- does one have to be broken down and rebuilt different to deal with fear, addiction, etc?

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6. 6. tweetyfelix 05:23 PM 12/15/10

   As someone in the field who works with trauma, I would like to share my thoughts in response to your question - does someone have to be broken down to erase fear?
   
   I work with abuse survivors who have experienced some of the worst things one person can do to another. They report their experiences are often about their abusor having control over them.
   
   As a practitioner, I see my role as empowering clients, to walk along side them in their journey, and to help them develop new skills to manage their trauma. I am also an EMDR practitioner (search google) and have exceptionally good results in addressing fear components when working with abuse survivors.
   
   I agree that when we go to change something in our life, it is good to have a plan of what we are going to substitute the action we are replacing. For example, if I want to give up coffee (never going to happen, but if I did), I would want to have a plan of what I am going to do instead of drink coffee, and this would need to be a specific plan. Every morning instead of drinking my coffee, I would fill my coffee cup (a visual trigger) with berocca instead. This would be a specific plan.
   
   Short response I think that breaking someone down adds to the process of dis-empowerment - it may produce some results, but at what cost.

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7. 7. iJonnyV in reply to tweetyfelix 09:12 PM 12/15/10

   Tweetyfelix
   
   Thanks for the response. Your answers and experience really helped putting things in perspective. The coffee analogy was a perfect example.

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8. 8. DrLPalmer 10:43 PM 12/15/10

   The Autonomic Nervous System sympathetic branch contains a biochemical antagonist to the biochemical fear state of epinephrine/adrenalin--Anger(Norepinephrine/noradrenalin)!
   Therapists have long used the biochemically neutralizing effect of feeling and intensifying fear/terror feelings/emotions to overwhelming levels, followed by generating sufficiently extreme and prolonged rage/anger (norepinephrine) that provides permanent relief from the debilitating terror in the gut. The key is to provoke the rage to an extreme level and to maintain that level in order to produce sufficient norepinephrine to bring about the neutralization of fear. The staff must be trained in order to accomplish this clearing, trained to be objective and to avoid calming or reducing the intensity of the rage. Humans typically avoid rage because of possible violence, harm, damage and unpredictability. By provoking rage, properly trained therapists and staff can accomplish results in one session that might take years using other therapies.
   Stewing around in the epinephrine state by reliving the fearful events is just hopelessly wearing and stressful.
   Once observed, the resulting natural, calm, normal demeanor of the formerly fearful person appears miraculous and mysterious. Release from fear is freedom from constriction, natural deep breathing occurs as well as clear thinking. The process can be physically draining because of the physicality involved.
   Remember the TV series, the Incredible Hulk, where after feeling terror the character would transform into an incredibly strong rage-filled hero? Each of us contains within us the incredible hulk biochemistry for flushing out our emotional terror through therapeutic rage. This biochemical process is a naturalistic resource. The only barrier to using anger therapeutically is the fear that people have of the rage of others that from earliest childhood is suppressed, punished or rewarded. We ordinarily try to bargain with an angry person, to calm, to cajole, to avoid anger in ourselves and others. Calling attention to uncomfortable emotions by naming them and continuing through to the final release indicates a fundamental dedication to the person in need. Persisting in the production of both epinephrine and norepinephrine is experienced as passing through hell. The freedom experienced when emerging at the other side is always worth the experience though. The person frozen in fear requires an objective and unafraid therapist to assist, provoke, maintain, and finish the process to full completion.
   
   

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9. 9. yiddishpablo 03:30 PM 12/19/10

   This article is very informative, thanks. It makes a lot of sense that the longer a memory is contained and (when tagged with an emotion by the amygdala) the more difficult it is to remove that memory or change the tag because of plasticity. Not to mention the fact that the "memory centers" (ie the hippocampus) and the amygdala are both part of the limbic system - so they are physically connected.
   
   I have some questions though, being only slightly knowledgeable in the field of neuroscience, though intensely interested in it. What about "abstract" fears, animal fears? Nothing particularly bad happens in the dark when we're children - if nothing else, a young young child is quite accustomed to the dark (having been in the lightless womb - though that is beyond memory). And yet they are afraid. This fear of "the unknown" may be instinctual - however, based on this article, shouldn't it be overcome rather quickly instead of persisting for years?
   
   Night after night, nothing bad happens and yet many (if not most) 6 year olds (having years of quiet nights) are still afraid of the dark? I suppose, if I were attempt to answer my own question from my limited knowledge I would rely heavily on the fact that the memory system is still developing. That is to say that night after night after night nothing happens, but there is little solid memory of this. Memory doesn't kick in until 4 or 5 or somewhere in there.
   
   Going along with the point of the article, I guess this makes sense. 4 or 5 years of having an undefined fear of the dark is a long time. Thus, it takes a long time to overcome this - another 3 or 4 years, sometimes longer.
   
   Going along the same rout - I think it would be interesting to see how connected memory is to fear. This might help to answer my question. If there was a study on individuals suffering from retrograde amnesia who have a fear of some definable thing (like cats for instance)...
   
   Of course, such a study isn't possible for humans - if you ask someone has retrograde amnesia (which is in of itself very rare) what they're afraid of, they won't be able to remember.
   
   Perhaps, if you got the mice or rats to develop a fear of a blinking red tile - erased the memory of half the mice and measured the amnesia-mice reaction to the tile (without the shock) against the non-amnesia-mice it would yield some answers.
   
   Maybe such a study has already been done in some form or another. I would be grateful to anyone who could give me any kind of answer.

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10. 10. rwstutler 08:29 PM 12/21/10

    Way too many people want to mistake their conscious awareness of what they are thinking and feeling with what is actually happening inside their brains. The fact is that most of what goes on in the brain is not accessible to conscious awareness.
    
    What I get from the article is not that memories cann be erased, but that an amygdala response to a memory can be moderated, or altered biochemicaly, in a specific manner and in a specific time frame.
    
    While it is hard to see how a 24 hour window can be of significant therapeutic use (in the field for soldiers or in the home for abuse victims), it is a starting point.
    
    Adrenaline as a prophylactic to traumatic memory association to an amygdala response? Sounds promising. Hard to be traumatized when angry, or to see ones self as powerless and as a victim when one is enraged. Though I wonder - does the anger, the rage (the extended exposure to adrenaline) pose a threat of a traumatic memory association (linking a memory with an amygdala response) in its own right?

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11. 11. bucketofsquid in reply to Razza 10:05 AM 12/28/10

    If your "solution" is so wonderful, why hasn't it been written up and submitted for peer review? As a different Sci-Am article points out, most published theories end up getting disproven. Could it be that you know that would happen so you are trying to bypass the peer review process?

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12. 12. bucketofsquid in reply to iJonnyV 10:13 AM 12/28/10

    Breaking someone down and rebuilding them in the controller's desired way is exactly what the U. S. Marine Corps does. The end result is a highly affective marine with a LOT of general anger and an easily triggered violence response. Growing up on Marine Corps bases was not fun at all.
    
    I highly doubt that the "Christians" your parents produced were very Christ like in their behavior.

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13. 13. bucketofsquid in reply to DrLPalmer 10:22 AM 12/28/10

    Thanks for the Scientology take on fear. How, pray do tell, is building in a rage response to an event in any way superior to a fear response? It sounds more than a little sociopathic. Any "treatment" method based on the meanderings of a professional liar are suspect. Particularly when so many of the leading Scientologists have been convicted of fraud.
    
    What is your doctorate in? Are you a doctor of poetry?

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14. 14. rwstutler in reply to bucketofsquid 04:00 PM 12/28/10

    The idea that anger can preclude the formation of the emotional links that are associated with PTSD is interesting and worth further thought.
    
    Your ideas about the way Marine DI's condition their recruits are also worth further thought. They are similar to the 'violentization' process which Lonnie Athens speculated about in "Why They Kill", but the USMC conditioning process is different in very specific and significant ways. The Marine Corp way, and Army way, etc, was created to counter a problem of soldiers not firing their weapons at the enemy while in combat. The effect of the boot camp experience, once the problem was acknowleged and effetive conditioning methods created, was to make every marine or soldier a rifleman. See "On Killing".

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