Understanding Fear and the Amygdala

Understanding Fear and the Amygdala

This brain region drives our experiences of fear, among other things.

Close to two hundred years ago, a doctor dissecting a human body first recognized the region of the brain that would come to be known as the amygdala (Ledoux, 2007). Since this region was shaped like an almond, and about the same size, too, it was named after the Latin word for almond, which is, of course, amygdala.

It was originally thought that the amygdala was a standalone region of the brain, but researchers soon observed that it had closely related and nearby structures that seemed to be involved in the same activities. After this, a fierce debate raged about which parts of the brain were close enough in proximity and in function to count as part of the amygdala.That scholars eventually agreed to call the original almond-like shape, as well as some other adjacent brain parts engaged in very similar activities, the “amygdaloid complex”, or just ‘amygdala’ for short.

So to summarize, the definition of the amygdala is a tiny brain region that is highly involved in certain emotional and cognitive processes – more on those in a moment. This region is a very evolutionarily old part of the brain—it is involved in very “primitive” functions such as our sense of smell, but it is also highly interconnected with evolutionarily newer parts of the brain (Swanson & Petrovich, 1998).

“Feed your neocortex, starve your amygdala.”
― Emmanuel Apetsi

Function of the Amygdala

The function for which the amygdala is best known is its role in fear conditioning (Janak & Tye, 2015). This means that it is highly involved in both the experience of feeling fear and the experience of learning to fear something. When we have an experience that frightens us, our amygdalae (that’s the plural of the word!) help the more complex regions of the brain, such as our prefrontal cortex, encode (a fancy word for remembering) this experience as something we should be afraid of.

While fear conditioning is the best studied of the amygdala’s many functions (Ledoux, 2007), the amygdala is involved in many other emotion-related processes (Janak & Tye, 2015). It has become clear that the amygdala also fires – in other words, shows a lot of activity – when we have positive emotions as well as negative emotions, and when we see things that are rewarding as well as threatening (Baxter & Murray, 2002).

In other words, when we are motivated to move toward something or away from it, the amygdala is functioning as part of that process (Janak & Tye, 2015). It is also involved in our behaviors that seek to meet basic needs, such as seeking comfort, eating, and sexual activity (Ledoux, 2007). It even is activated in accordance with what we are paying attention to. So one shorthand that has been proposed is that the amygdala’s job is to notice when things are emotionally relevant to us (Ledoux, 2007).

The Amygdala and PTSD

It appears that the amygdala is significantly changed in people who have posttraumatic stress disorder, or PTSD (Morey et al., 2012). The amygdala of a person with PTSD shows more activity in response to emotion-inducing images than the amygdala of a person without PTSD. People with PTSD have smaller amygdalae on average, too. At the same time, these phenomena are not worse in people with worse PTSD symptoms. This suggests that people with PTSD may have been more susceptible to strong reactions to stressful events in the first place.

The Amygdala and Anxiety

Since anxiety and fear are somewhat synonymous, it should not surprise us that amygdalae look different in people with anxiety. Similar to the amygdalae of people with PTSD, the amygdala of an anxious person is likely to be smaller and more reactive than the amygdala of a person without anxiety (Davis, 1992; Rauch et al., 2003).

In Sum

Perhaps you have read articles online or talked to friends or even healthcare professionals about what you can do to manage your amygdala. This is an admirable goal, but perhaps not the most effective way to think about how to get there. The absence of fear would bring us all sorts of very real, new problems. Also, we do not experience less fear by changing our brains – we change our brains by having new experiences. Psychotherapy is where we truly, although indirectly, work on the amygdala. Fear is the belief that something bad will happen, but every time we face something frightening in therapy, we break down that association a little bit. The amygdala’s response may just weaken a bit (Janak & Tye, 2015), creating more freedom in our lives. Hopefully you can gently and courageously face the fears you’ve been conditioned to have but that are holding you back.


● Baxter, M. G., & Murray, E. A. (2002). The amygdala revisited. Nature Reviews Neuroscience, 3, 563-573.

● Davis, M. (1992). The role of the amygdala in fear and anxiety. Annual Review of Neuroscience, 15, 353-375.

● Janak, P. H. & Tye, K. M. (2015). From circuits to behavior in the amygdala. Nature, 517, 284-292.

● Ledoux, J. (2007). The amygdala. Current Biology, 17(20), R868-R874.

● Morey, R. A., Gold, A. L., LaBar, K. S., Beall, S. K., Brown, V. M., …, & McCarthy, G. (2012). Amygdala volume changes in posttraumatic stress disorder in a large case-controlled veterans group. Archives of General Psychiatry, 69(11), 1169-1178.

● Rauch, S. L., Shin, L. M., & Wright, C. I. (2003). Neuroimaging studies of amygdala function in anxiety disorders. Annals of the New York Academy of Sciences, 985(1), 389-410.

● Swanson, L. W., & Petrovich, G. D. (1998). What is the amygdala? Trends in Neurosciences, 21(8), 323-331