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The Amygdala - centre of Fear, Anger, Anxiety, and Aggression

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There are hundreds of pages on this website, which has taken me thousands of hours to research, learn, and write. If I can to pick a small handful which is especially important, these 2 pages on the amygdala are definitely that. This is definitely one of the most that one brain function which people would understand more about, this page - on the Amgydala - must be it. 

The activation of the amygdala is intricately weaved into the web of all our biggest challenges in life. How well we do in life, how we react in critical scenarios, what regrets we have, what memories we create - all of these will depend on how well we can understand and dance with our amygdalae. 

There are 5 major things to know about the amygdala.


Let's get started. 

Regulates Fear, Anger, Anxiety, and Aggression

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Whenever I introduce the Amygdala, I compulsively state all the 4 emotions it regulates. Miss out on one and the picture of the amygdala is incomplete.

When the amygdala triggers, we will feel one or a combination of these emotions. Here, we notice several things. 

  • The emotions might exist individually by themselves. You might be angry at yourself for making a mistake when say you make a mistake playing the piano - but you're not aggressive, fearful, or anxious. You might have felt fear when you suddenly saw something move in the shadows, only to quickly realise it was merely a piece of paper flying in the wind. 

  • But mostly, we can observe these emotions in combination. 

    • When we are criticised openly by someone in a disrespectful manner, we might become very angry and aggressive - our voice turns louder, we stand up, and we might start thinking maybe this is the time all those imaginary punches we threw along with our Rocky movies manifests into reality. But underneath the anger and aggression, there is also fear. Fear of losing face. Fear of losing status and being thought less of. Fear that you might actually be wrong, and the pain that we've come to associate with being wrong. 

    • A somewhat shocking experiment by Gregory Berns et al from Emory University hooked participants up to a device that would give them a minor electric shock randomly (full paper linked here). When given the choice, participants chose to receive a larger shock than to deal with the uncertainty of not knowing when the shock comes. This presents a more complex interplay between the emotions:

      • At a basic level, the minor electric causes us to feel fear (we can see this through the brain scans of the participants), because it inflicts onto us physical pain

      • But there is a secondary fear coupled with anxiety - that is the uncertainty of when the electric shock will be delivered. Waiting for something bad to happen to us is so pleasant it causes us mental pain

      • To fight off mental pain -  in the form of fear and anxiety caused by uncertainty, we are willing to suffer larger physical pain. One fear (tied to anxiety) is larger than the other.  


That it is the same part of the brain that regulates 4 important emotions gives us greater insight into human behaviour. When someone is angry, he might also be fearful or anxious. When someone is anxious, it is far easier for him to also be angry. When the amygdala is triggered by 1 of the 4 emotions, it is more readily activated for the other 3. 

We cannot understand anger and aggression without also understanding fear and anxiety. And it is with this understanding that we can look beyond or beneath the explicit behaviour of others, and of ourselves, to tackle what really troubles us. 

Automatic amplifier 

Image by Clay Banks

Mostly, emotions are automatic. You don't need to tell your brain, hey dude, time to get angry. Or hey brain - someone died, good time to cry. 

In fact, we now know that emotions can trigger before we even have time to accurately assess what has happened. In other words, sometimes the emotions are already running, and we just become aware of it. While we can't always control the initial trigger of emotions, we can control how we choose to respond to it. More on this later, stayed tuned. 

Remarkably, your amygdala is incredibly sensitive and is able to pick up and respond to stimuli which are too faint or fleeting for your conscious brain to pick up. Take the sweat of people who ran a marathon and the sweat of people who jumped out of the plane free-diving. You can't tell the difference between the 2 consciously, but your brain can - your amygdala lights up in a brain scanner when you smell the sweat from fear, and has no reaction to sweat from physical exertion. 


An even more astounding example is Patient TN. After suffering from a stroke, TN became cortically blind. Researchers from Switzerland and The Netherlands placed TN in a brain scanner, and showed him images of faces - some were looking away, some had a blank look, and some were staring directly into the camera. Amazingly, his amygdala was activated by these images of people staring directly at the camera - the most threatening look of all the faces. Remember, TN was cortically blind! (Read the full paper here.)

A second thing to note is that all 4 emotions regulated by the amygdala are very strong emotions. This is a major reason why the Amygdala plays such a pivotal role in our lives. Think back on a time when you had one or a combination of the emotions above. Just by thinking about it now, even if you are safe and comfortable in your chair on your bed or trying to kill boredom scrolling through your phone, you start feeling a little bit uneasy. Your blood pressure increases just a little, your heart beats just a little faster. Some of these emotions stay with you for a very long time, even if they occurred far in the past, and affects your thinking and behaviour even till today: 

  • Most of us are fine being around dogs and cats, but if you've been bitten by one, you might have a phobia that lasts a lifetime. Similarly, you might have had a failed attempt at public speaking, which causes you to feel anxious and fearful when the next public speaking requirement arises. You might try to avoid such a speaking requirement, pushing it to someone else. 

  • You might be very angry with someone, and this anger never completely quells. You might forgive but never forget, or you might simply never forgive or forget. 

  • You can still vividly remember the anxiety that you felt when you lost something very important, even though you later found it (and still have it today).

Because these emotions are so automatic and so strong, they act as an amplifier that forces you to pay attention. Say you scroll through your newsfeed and you see some pieces of news you wanted to read, but then you got distracted by something else. No problem, you can ignore or forget it completely.

But you can't ignore fear or anxiety or anger or rising aggression. You can't just tell yourself, ah it's ok, we'll pass on this feeling of fear this time. The next time I feel fear, then I'll look into it. Whether you are ready or not, the emotion hits you - it doesn't whisper softly into your ears but it roars loudly at you.

What happens next depends on where we focus our attention. If we focus our attention on just the emotion, we will simply be carried along in the wave of what we're feeling. But if we focus our attention on why we feel the way we do, then we begin to understand the source of our emotions, and this is something we can address.

To end, I can't resist sharing some of my favourite examples of fear amplification. It's doesn't really fit in so nicely here does it, but I always found these quite funny:

1) Many people around the world, regardless of race, religion, or culture, get pretty terrified by cockroaches, especially if they fly

2) Some people scream when they see others on a rollercoaster

3) Moviegoers are spooked by horror films, even if they know the plot and are surrounded by friends

Think about it - in all 3 situations above, there is literally nothing to be afraid of. You are completely safe. How many people have ever been harmed by a cockroach? Or watching someone else on a roller-coaster? Or have ever been haunted by a ghost from the horror film while at the cinema? 

The Amygdala can trigger very quickly

The amygdala, being the regulator for emotions like fear and anger, is often portrayed in a negative light. "If only we had no fear / if only we can always remain calm, we will be so much better".


Fear and anger are not absolutely bad. Sometimes, they can be very accurate indicators: fear can keep us humble, indicating to us that we have not prepared well for the coming task; when we get angry over something, it can be an indicator that this something means a lot to us. (Separately, you can check out this piece: Are emotions bad? Is it really good to be like Spock?)

More crucially, most of us might not even be here if it wasn't for the amygdala. Think about our ancestors in the past, living in the grasslands. There is a sudden sound coming from the shadows. This causes the amygdala to trigger (and as we will see, triggers at a remarkable speed). Suddenly, the senses of our ancestors are heightened, and they are ready to make a run from potential danger. Now imagine if there was no amygdala - our ancestors paused and analysed the evidence. At this time of the day, what is the probability that the sound is coming from a predator? What is the cost of me getting up from my sleep to check? And as they analyse and analyse, a tiger springs up and enjoys a tasty human supper, garnished beautifully by the dying regrets of delayed analysis. 

So the amygdala has kept us alive as a human species. And the condition for this to happen is that the amygdala must be able to trigger very quickly. If it takes too long for the amygdala to trigger, the threat might already have happened. And unsurprisingly, as we examine the neurobiology, we observe that your brain has developed a strategy that enables your amygdala to trigger very quickly, what we call the amygdala hijack.

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The picture above (click to magnify) shows the normal process of what happens when we see something.  The image captured by our eyes is sent to the Thalamus - which serves as a way station that directs incoming information to the right part of the brain to analyse. In this case, the image is sent to the visual cortex, who works out pixel by pixel, line by line that what you've seen is a horse. 

Even though the human brain is truly amazing and is able to complete this multi-step process remarkably quickly, it's could still be too slow. 

Instead, our brains evolved to short-cut this process - our amygdala hijack.


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What happens in the event of the amygdala hijack?

  • We see something.

  • The signal is transmitted to our thalamus. 

  • And at this point - the thalamus has a sense, hold on, this could be something dangerous. We can't afford to send it to the visual cortex to accurately decode before sending it onto the amygdala to determine if it's dangerous.

  • Let's skip the visual cortex and go to the amygdala - the amygdala has hijacked the process.

  • The amygdala can also decode what you have seen, but far less accurately. 

  • And you see something that looks a bit like a snake, and it could be dangerous, and your amygdala goes crazy! It yells out all sorts of signals to different parts of your brain and to your body, RUN!



And you might find yourself in the situation just like above. You see a snake and run from it. Until you take a second look - and it's a prank, it's a fake snake. 

One more interesting fact when you re-examine at the video above. Notice how quickly the NBA player moves away from the fake snake. Biologically, there is a second short-cut. Usually, the final order for movement of any part of the body comes from your cortex. But in times when there is extreme activation of the amygdala, the amygdala bypasses your cortex and issues the command to move. In other words, the amygdala hijacks the process not once but twice. 

I would like to stress once again that our brains and bodies have evolved to enable the amygdala hijack - because such hijack has kept us alive. It allows us to react to danger at the fastest possible instance - even before we are consciously aware of what's happening. And this served us well for tens of thousands of years.

The issue comes when we misjudge the danger. Sometimes, we misjudge a harmless toy snake, an innocuous prank.
But think about when we misjudge something more serious. 


A policeman sees a member of the public of a different race. Already, there is an elevated sense of caution - the amygdala is already triggered and active. And that person suddenly puts his hand into his pockets, and the policeman catches a glimpse of a black object. It could be dangerous. You get a full-blown amygdala hijack - all the alarm bells start ringing. The policeman might then decide, I have to get this guy before he gets me. And the policeman pulls the trigger (remember - amygdala hijack part 2). And just maybe, what falls out of the hand of the member of the public - that black object - it's not a gun, it's a handphone. The guy was scared, he wanted to film what was happening. But the policeman was also scared. And one of them ended up dead. 

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One final example, which we probably all have some experience with. You give a presentation at the office. A colleague smiles warmly and politely offers an additional point that you missed out in your presentation. Friendly face and demeanour, nothing that he does cause any alarm. Your amygdala doesn't trigger. You quickly acknowledge his point. 

Now imagine you have given the same presentation. The colleague offers the same point. But he does so in a different manner. His face is plastered with disapproval. His body languaged displays impatience. And he starts off with an insult. Before he even gets to his point, you are riled up. An amygdala hijack has already occurred. You are angry (and as we covered above, also fearful).  You are ready to lash out in aggression. 

In the first case, both parties end up better off. In the second case, with the trigger of an amygdala hijack, both parties end up worse off. There is also a higher likelihood that the content of the discussion becomes neglected; instead, the focus switches to the people involved, and not the point raised.

Part 2 

Ok, so this has been quite a heavy chapter. Now's a great time to head to the fridge and see if there is anything to eat. Ok I confess, I'm actually pretty hungry myself so I'm going to raid the fridge. 


In Part 2 of our introduction to the amygdala - we will examine some interesting questions, and conclude our 2 final points about the amygdala:

  • If the amygdala is about fear, is there a difference in the nature of fear, b

    • between the fear of snakes

    • the fear of walking down a dark alley at 3 am

    • or the fear of someone you meet later in life, maybe in your 40s?

  • Further, if you continually learn throughout your life new things that are scary, are you able to also unlearn fear?

  • Finally, we will also explore a concept often portrayed in popular media - that there are 2 sides of us: a thinking/rational side, and an emotional/angry/fearful side. Is this true? 

Read more in Part 2 of the amygdala here

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