Amygdala... hijacked!

Van Gogh, Self Portrait with Bandaged Ear, 1889

I remember reading this article about eating disorders and the amygdala by Charlotte's therapist Samantha. Zylstra.  I also recall talking to Zylstra about it.  The key idea is that the brain feels (a threat) first.  Then the pre-frontal cortex will make meaning of the fear.  It will "tell a story" about the feeling to rationalize it.  The story can be misaligned.  Here's the beginning of the article:

“Everyone in the waiting area is staring at me. They all know I’m so fat and ugly.”  Mary’s words choked out of her as she held back tears of embarrassment.  Mary sat down and spent the first ten minutes of her session focusing on her breathing.  I observed a noticeable calming in her body.  Once calm, Mary reported just before her session, she had come across a memory of the day she found out her family was going bankrupt and how embarrassed she had felt.  Mary was aware she had used the same word embarrassed to describe the waiting area and her family’s bankruptcy.  Using this awareness, Mary named that feeling fat was protecting her from thinking too much about the trauma of her past.

Kimberli McCallum would describe Mary’s experience as, “Out of balance circuits mis-assign meaning and generating false stories to explain shifts, attributing any disappointment, difficult emotion or pain to issues such as weight, shape or food.”  Mary’s brain was doing exactly what it is designed to do when perceiving an intense fear.  Her amygdala recognized a strong emotion and went into autopilot, working faster than her hypothalamus to pump adrenaline into her body and help her.  In that autopilot response, Mary had mis-assigned her intense embarrassment to everyone in the waiting area staring at her because she was fat and ugly

From Know Your Brain

the amygdala has become best known for its role in fear processing. When we are exposed to a fearful stimulus, information about that stimulus is immediately sent to the amygdala, which can then send signals to areas of the brain like the hypothalamus to trigger a "fight-or-flight" response (e.g. increased heart rate and respiration to prepare for action).

Interestingly, research suggests that 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 may be 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 really are in great 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 may be 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. For example, 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.

Although the amygdala is well-known for its role in fear responses, there is now a great deal of evidence that suggests its contribution to behavior is much more complex. For example, the amygdala seems to be involved with the formation of positive memories, like earning a reward in an experiment. And damage to the amygdala can impair the ability to form these positive memories, just like it can affect the ability to form memories about negative events like the foot shock mentioned above.

Because of research like this, researchers have been forced to expand the role of the amygdala beyond that of just a threat detector/fear generator. One popular perspective suggests that the amygdala is involved with evaluating things in the environment to determine their importance—whether their value is positive or negative—and generating emotional responses to those stimuli that are considered important.