The amygdala is a brain structure often conceptualised as the 'fear centre of the brain'. It's common to see it blamed in science journalism as the cause of emotional disturbances, anxiety, stress, and of course, fear.
I quote from this recent Atlantic piece:
Negative emotions such as anger and fear activate the amygdala, which increases vigilance toward threats and improves your ability to detect and avoid danger ... makes you fight, flee, or freeze—not think, "What would a prudent reaction be at this moment? ... This makes good evolutionary sense: Half a million years ago, taking time to manage your emotions would have made you a tiger’s lunch ...
Odds are, you no longer need your amygdala to help you outrun the tiger without asking your conscious brain’s permission. Instead, you use it to handle the nonlethal problems that pester you all day long. Even if you don’t have tigers to outrun, you can’t relax in your cave, because the emails are piling up.
The reasons for this odd relationship between the amygdala and ancient tiger lunches are complex.
One is because this particular, absurd story about how our stress response evolved in a time when we were apparently perpetually running from lions on the savannah has captured the popular imagination. But I talk about that more elsewhere (in short though, it did not, we were not, and our stress response is usually perfectly suited to modern life).
Another reason for the demonisation of the amygdala comes from the fact that these two little almond-shaped brain structures seem to be very influential in the learning of fear responses. If you suffer some kind of brain trauma to these little structures, you might find that you no longer exhibit a fear response. If we stimulate part of the amygdala in a non-human animal, we can see fear responses. If we mess with the amygdala in countless ways, these ways often implicate it in the production of learned fear responses.
This kind of research was popularised outside of academic circles. People now had a name for the 'fear centre of the brain', and media outlets were quick to share the news.
And then, in the 1990's, science journalist Daniel Goleman popularised the idea in his book Emotional Intelligence. In this book, he describes the purported amygdala hijack---in which the amgydala 'hijacks' the brain if it detects that we perceive something threatening. It takes over milliseconds before the 'neocortex', the so-called 'rational' brain, can get in the way. Once hijacked, the amygdala would produce a 'fight/flight/freeze' response and then I guess the point is we become idiots or something. Of course, that's not how either of those brain regions work.
Nonetheless, journalists and management schools ate the idea up, and now every McKinsey consultant will encourage you to 'get out of the amygdala and into the frontal lobe'1 and every lazy blogger will trot out this old trope.
Even thirty years later, the amygdala still appears in "science" journalism as the enemy, apparently still haunted by the spectre of bored tigers after thousands of years of evolution and inconveniently capturing the rest of our brain in its improbably large clutches at the terrifying sound of, I guess, email notifications.
Here's the truth. The amygdala is not the fear centre of the brain.
Something worth noting, to the careful eye, is how on the Wikipedia page for this popular concept of 'hijacking', at the time of writing, there is not a single reference to any academic article on the subject.
The reason is because this heuristic is far too simplistic to be useful to someone who is actually interested in how the brain works. The amygdala isn't the centre of fear processing, it has a (very complex) hand in all emotional learning. The fact is that the fear literature is over-represented because its really, really easy to scare things in a lab and much harder to produce other kinds of emotions.
Indeed, even Goleman notes:
not all limbic hijackings are distressing. When a joke strikes someone as so uproarious that their laughter is almost explosive, that, too, is a limbic response. It is at work also in moments of intense joy.2
From good to bad, the amygdala seems to be a structure that helps us understand what things in the world are important. It helps us focus our attention on those things, and helps us remember how important those things are when we see them again. If we'd like a more useful heuristic than the 'lion detector' one we've been given, we might say the amygdala is an emotional intensity detector, or the thing that charges our perceptions with emotions.
Most crucially, we don't see times where the amygdala is 'taking over' from other regions of the brain. We see that the amygdala is always involved. It is simply far more visible when the emotional intensity is higher, because of course it would be. That's what it does. Help detect emotional intensity.
This is made even more clear when we look closely at its operation. For example, we see it become active when participants view distressing stimuli. But we also see it active, only less so, if the participants are asked to reappraise the stimulus (pdf; pg 44). A person crying outside the church might be a funeral attendee. Heightened amygdala activation. Reappraise it as a person crying at a wedding, the amygdala activation reduces.
Here, the amygdala is obviously not 'taking over', it's simply mapping its activation to how emotionally charged the situation is. It's not clear that the amygdala generates anything at all, let alone some kind of outsized stress response.
So what are we left with? The idea that sometimes we are emotionally distressed by things we shouldn't be is a helpful one. That's why we were so excited about the amygdala in the first place. It was the emotionally distressed thing, and we could call it out for being ridiculous. It's nice to be able to distance ourselves from those parts of us that are inconvenient or confusing.
But focusing on the amygdala misses the point. It's not our brain that's the enemy. The amygdala is simply a distraction from what's important. It's the way we're responding to the world that's causing the problem.
In the mean time, you'll have to go find another bad guy.
The limbic system is a hypothetical collection of brain structures, of which the amygdala is often thought to be a small piece. 'Limbic hijacking' is interchangably referred to as 'amygdala hijacking', which should clue one into just how thoughtless this heuristic really is. ↩