Are You Neuroscientifically Challenged?
February 19, 2020
How weird is it that there is a website with the name NeuroscientificallyChallenged.com? 🤓
You might be wondering how I came across the website.
I had a hard time emotionally for many months after my cardiac arrest. I was wrecked with fear – a constant, uncontrollable fear – that I would have another cardiac arrest and I wouldn’t be so lucky the second time. My doctors told me there was little risk of such an event but I could not escape the thought that I almost died. I was impossible to be with as the fear overwhelmed my other emotions and wore me out physically and mentally. As I look back on that time, my reaction was one of being the victim – a passive “my brain is in control” reaction. I eventually began to understand that my fear and associated anxiety were irrational but they weren’t going to go away by themselves. That’s when I decided to show up and lean into my fear and anxiety – it took months but I remember that it was almost a year to the day after my event that I felt the fear and anxiety dissipate.
Maybe it is the engineer in me, but the first step in my showing up and leaning in was to understand how our brains deal with fear – and that led me to understanding the amygdala. My understanding helped me to visualize where my fear was coming from and “see” that I could use thoughts to calm the amygdala. It was a battle - the amygdala may be small but it carries a big punch.
The amygdala is a collection of nuclei (a collection of neurons that work together in performing certain functions) located within the temporal lobe (the lobe of the brain located closest to the ear which contains structures that are important for memory, language, and hearing, along with other functions). The word amygdala comes from Latin and translates to "almond," because one of the most prominent nuclei of the amygdala has an almond-like shape.
There are two amygdalae - one in each cerebral hemisphere. While each serves a slightly different function, both amygdalae process fear.
The amygdala is a component of the limbic system (a group of structures associated with emotion, including the hippocampus, amygdala, and cingulate gyrus). It plays important roles in emotion and behavior and is best known for its role in the processing of fear.
Our understanding of amygdala function can be traced back to the 1930s, when researchers removed the amygdalae of rhesus monkeys and saw drastic effects on behavior. Among other things, the monkeys became more docile and seemed to display little fear.
When we are exposed to a fearful stimulus, information about that stimulus is immediately sent to the amygdala, which then sends signals to areas of the brain like the hypothalamus (group of nuclei that lies just below the thalamus and is crucial in the maintenance of homeostasis, as well as reproductive functions, fight-or-flight-or freeze reactions, feeding, and sleep. The thalamus is a subcortical structure that serves as a relay between sensory and motor systems and the cerebral cortex and also plays important roles in consciousness and arousal. These signals sent by the amygdala trigger a "fight-or-flight-or freeze" response (e.g. increased heart rate and respiration to prepare for action).
Information about potentially frightening things in the environment can reach the amygdala before we are even consciously aware that there’s anything to be afraid of. There is a pathway that runs from the thalamus to the amygdala, and sensory information about fearful stimuli are sent along this pathway to the amygdala before it is consciously processed by the cerebral cortex. This allows for the initiation of a fear reaction before we even have time to think about what it is that’s so frightening.
This type of reflexive response can be useful if we are in danger. For example, if you are walking through the grass and a snake darts out at you, you don't want to have to spend a lot of time cognitively assessing the danger the snake might pose. Instead, you want your body to experience immediate fear and jump backward without having to consciously initiate this action. The direct pathway from the thalamus to the amygdala is one way to achieve this type of response.
In addition to its involvement in the initiation of a fear response, the amygdala also seems to be very important in forming memories that are associated with fear-inducing events. If you take mice with intact amygdalae and play a tone right before you give them an uncomfortable foot shock, they will very quickly begin to associate the tone with the unpleasant shock. Thus, they will display a fear reaction (e.g. freezing in place) as soon as the tone is played, but before the shock is initiated. If you attempt this experiment in mice with lesions to the amygdalae, however, they display an impaired ability to "remember" that the tone preceded the foot shock. You can play the tone and they will continue about their business as if they have no bad memories associated with the noise.
The amygdala probably also plays a role in anxiety. While fear is considered a response to a threat that is present, anxiety involves the dread that accompanies thinking about a potential threat—one that may or may not ever materialize. Studies suggest that the amygdala is involved in experiencing anxiety, and that it may be overactive in people with anxiety disorders.
I hope you never experience the kind of fear and anxiety I did after my event. But if you do, put your mind to work in calming down your amygdala!
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