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Removing the fear
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Blogger Profile

David Manly
Freelance Science Journalist
Toronto Ontario CAN

David Manly is a freelance journalist who will blog about a wide range of topics that all fall under the umbrella of zoology and ecology. While his expertise lies with reptiles and amphibians, he has a wide array of knowledge and interest in all animal species - from the sponge to the great ape. He hopes you will enjoy his blog, as he plans to make it both entertaining and enjoyable (as well as fill it with interesting facts, tidbits, photos and videos).

My posts are presented as opinion and commentary and do not represent the views of LabSpaces Productions, LLC, my employer, or my educational institution.

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Sunday, October 9, 2011

First off, I would like to apologize for not posting as recently as I would have liked to on LabSpaces. I've been with LabSpaces blogs since the very beginning, and I would never stop posting ... but, life got in the way.

Over the past few months, I've been busy writing and working, and I let a few things fall away.
So, I apologize for my absence, but I'm back now and will post more frequently. And, I have a very interesting post to share. I hope you enjoy!

Fear is one of the most powerful emotions that a human can experience, and it can affect every human being on the planet. However, how do you categorize an emotion?  People feel emotions in different ways, and some are more affected by them than others. 

The etymology, or origin of the word, is not well known.  According to Merriam Webster’s online dictionary, it comes from the Middle English fer or the Old English fǣr, which stands for sudden danger.  This describes the event that caused the emotion, but not the emotion itself.  The emotional state of fear was first noticed and defined in the late 12th Century, and is the same definition that we know of today. But is there a better one out there?

To define an emotion is a complex task, but to describe one is more difficult.  How do you describe an emotion, like love or hate, as it all occurs in your own mind?  Charles Darwin, the famed creator of the theory of evolution, created a wide array of other works, including a book entitled The Expressions of the Emotions in Man and Animals.  Within those pages, he went at great lengths to describe, in his opinion, what occurs within an individual’s body and mind during the creation and expression of different emotions.  His description of fear is almost hauntingly pitch-perfect in its description.

“Fear is often preceded by astonishment, and is so far akin to it, that both lead to the senses of sight and hearing being instantly aroused. In both cases the eyes and mouth are widely opened, and the eyebrows raised. The frightened man at first stands like a statue motionless and breathless, or crouches down as if instinctively to escape observation. The heart beats quickly and violently, so that it palpitates or knocks against the ribs... That the skin is much affected under the sense of great fear, we see in the marvelous manner in which perspiration immediately exudes from it... The hairs also on the skin stand erect; and the superficial muscles shiver. In connection with the disturbed action of the heart, the breathing is hurried. The salivary glands act imperfectly; the mouth becomes dry, and is often opened and shut.”

"Should I stay or should I go now?"

Fear is simply an adaptive response to danger, either physical or mental. The response to the stimuli results is what is known as the fight or flight response, and it evolved in animals and early man as a way to respond to approaching danger.  While modern individuals do not often experience the same difficulties early man did, the response is still as potent.

The response was first categorized by Walter Canon in 1915, and is characteristically triggered by the release of epinephrine and acetylcholine, which are also associated with stress.

The biology of the fight or flight begins with an external stimulus that your mind interprets as frightening.  It can be anything ranging from a venomous snake, to falling from a great height or even public speaking.

When you are confronted with a potentially scary situation, your brain kicks your body into a hyper-prepared state.  Your breathing is hastened, your heart beats faster and your muscles tense up.  As well, you begin to sweat, digestion slows, stored nutrients are released for quick use of energy, your pupils dilate, peripheral vision decreases and your instantaneous reflexes are accelerated.  All this is occurring while your brain evaluates which response would fit your particular situation: fight or flee.

The main area of your brain responsible is the amygdala, a small almond-shaped structure at the convergence point for your senses.  The amygdala’s main role is in emotional processing and learning, in that it allows you to learn from fear and adapt your behavior.

Fear is also an excellent tool for learning, in which the amygdala is involved, and can result in a change behavior pattern.  On the other hand, the cascading response of hormones is so strong, that it can often override common sense and cause changes in your behavior.

For example, if you were walking down your usual path home in a ‘safe’ area, you would not feel the least bit frightened.  However, if you were violently assaulted and robbed, you would remember that particular experience each and every time you walked down that particular street.  Therefore, in order to avoid that feeling, you would alter your behavior to avoid that particular negative sensation.  An emotional state is creating a negative physical response, in order to negate a possible re-occurrence of the negative emotion, using a process known as conditioning.

Can you remove the fear?

On March 13, 2009 in the journal Science, a paper was written by Han et al. entitled “Selective Erasure of a Fear Memory.”

In this paper, the researchers selectively targeted and eliminated neurons in the lateral amygdala (LA) that contained a fear conditioned memory in mice.


Neurons in the LA possess the ability to secrete a cAMP response element-binding protein (CREB), and when secreted, they are activated for fear memory creation.  Simply put, if neurons express high levels of CREB, they have a greater chance of being selected to store fear memories. 

This was induced in certain neurons in the LA of mice by the injection of a modified Herpes simplex virus, so that the scientists could be certain of a specific area where a fear memory would most likely occur.  The virus also made those neurons vulnerable to Diphtheria toxin (DT).  The researchers knew that cells that were induced to secrete high levels of CREB were three times more likely to be selected for a fear memory.


The fear memory was created by placing a mouse, with enhanced CREB cells in the LA, into a fear response box.  A non-threatening tone was them played followed by the floor being briefly electrified.  The response from the mouse, freezing in place, was monitored and recorded.  Then, the experiment was repeated a few more times and then the tone was played without the accompanying shock.  If the mice still froze as if the shock occurred, that would confirm that a fear-induced memory had been created.

Then, the researchers injected DT into the LA, in order to eliminate all the neurons with experimentally increased CREB.  After confirming that all the cells with increased CREB were destroyed, the researchers ran the fear-induced memory confirmation experiment again.  When the tone was played without the accompanying shock, the mice did not freeze.  The induced memory had been deleted (See Figure 1 below).

The experimenters had created a memory before the experiment took place to make sure that only the selected memory (the one induced by fear) had been ablated, not all memories.  When that was tested and the mice performed normally, it was determined that the experiment did not affect other memories, just the one selected.

Lastly, the researchers demonstrated that the mice could re-learn the fear-induced memory, despite the absence of approximately 10 to 20 per cent of neurons in their LA.  The re-taught mice showed responses almost similar to the control mice.


Figure 1 – LEFT: The experimental mice (CREB-cre) showed persistent memory loss of fear-induced memory compared to control mice (Cntrl-cre).  RIGHT: Experimental mice were able to re-learn the fear memory, and showed an increase in freezing to back to almost control levels.

The future

Does this research mean that in the future, everyone can be fear free?

Not exactly.

Firstly, in order to eliminate the fear response, it would have to be severe enough to qualify. Simply being afraid of sharks in the ocean would not qualify, but suffering from PTSD or a severe phobia would. Sadly, this research or method would not totally eliminate fear, but only remove the emotion. In fact, the sights and sounds would stay intact, but the memory itself would be removed.

If the technology existed to erase fear from a memory, would you use it? Or, does overcoming your fear make you a stronger person? If the fear is constantly erased from all your experiences, how will you ever overcome that which otherwise would hold you back?  Would you be better for it, or worse?


Han, J-H. et al. 2009. Selective erasure of a fear memory. Sci. 323: 1492-1496.

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