
The Amygdala
I published this in medium.com
One of the enduring questions of the neuroscience of embodiment is the underlying nervous system mechanisms of the relationship between how we respond to threats and how we engage socially. The reason this question is so important is that it determines both how we interact in the real world in real time, as well as how we have adapted to trauma, and how that can show up later in our lives.
I’ve posted before about the polyvagal theory and my problems with it. One of the things that I find most problematic about it is that it overemphasizes the role of the vagus nerve, and leaves out many well-explained processes governed by other parts of the brain. As I said in that article, “…there are things we’ll miss if we take Polyvagal Theory as The Way Things Are. Avenues of understanding we might not embark on, questions we won’t ask, different theories that are harder to understand but more scientifically valid … will be dismissed, or at least not talked about in therapeutic or embodiment circles.”
I thought I’d spend a little time talking about one of my favorite parts of our brains: the Amygdala. The amygdala is known to play a rather large role in how we process threats and deal with fear. It governs our ability to use conscious, critical thought when we are in situations of threat, and thus, also plays a role in our ability to participate in social engagement.
The amygdala are two small almond-sized nuclei on both sides of the temporal lobes of the cerebrum. They are considered part of the limbic system — the part of our brain primarily tasked with emotional processing.
There are two specific aspects of the role of the amygdala, that specifically overlap the polyvagal theory: the responses of the amygdala to facial expressions as well as production of facial expressions, and the ability of the amygdala to inhibit social engagement. In addition, I’ll talk a little about the amygdala and trauma.
The amygdala is known to respond more strongly to aggressive or threatening facial expressions than to others — making it an important part of neuroception. It is considered an extremely important part of the way we respond to faces. When the amygdala is damaged, we are less able to recognize threatening facial expressions. In addition, the amygdala is included in the network that is responsible for decisions about what facial expressions to create. It is involved in the ability to promote or impede different kinds of facial expressions. In fact, there is far more evidence of the involvement of the amygdala in creation of facial expressions than there is for the vagal nuclei. Of course, the idea of a ‘face-heart’ connection that is such a popular part of the polyvagal theory is kind sweet to think about, but actually, the evidence is clearer that the amygdala is totally stealing that thunder.
Because of the amygdala’s role in threat processing, it is directly involved in the suppression of social engagement behavior. The amygdala is part of a network which is, in a sense, our ‘alarm’ system — it mobilizes our fight/flight response, engaging the sympathetic nervous system. And, as such, this network inhibits our ability to participate in social engagement when activated. The term “amygdala hijack” was coined to describe this — this network’s hijacking of our ability to use our conscious, logical minds to make choices about our behavior.
Further, the amygdala has an essential role in what is called “fear conditioning.” Fear conditioning the association of basically neutral stimuli with aversive events. For example, if when you were a kid, you got non-fatally hit by a car at the same time you heard the sound of an ice cream truck, this may well mean that every time you hear an ice cream truck, you have an intense fear response.
As you might imagine, fear conditioning has a tremendous influence on how we experience trauma, and respond in our later lives to traumatic events. Again, the overemphasis on the polyvagal theory in relation to trauma is problematic, given the critical role the amygdala plays in fear conditioning.
Based on the evidence, someone could just as easily (in fact, I might even argue more easily) coin an “Amygdala Theory” to explain how we respond to threats, and when we are able to participate in social engagement. But I’m not suggesting that. What I am suggesting is that all of this stuff is way more complicated than we think, and we can’t focus too much on one particular set of processes in our brains to explain it.