The amygdala: fears, actions, and bigotry

Th Wisconsin county where I grew up had basically zero black people living there until 1990. Rumor had it that shortly after the first black family moved into my hometown, someone threw rocks through their windows. Actions can cement our biases, for better or for worse. Dramatic actions based on bigotry, say fear of a changing demographic, will literally change the brain. Neural networks grow more dedicated to a racist ideology when fearleads to action. Fear centers on the amygdala, which has anatomical connections to the cortex, which in turn influences behaviors. recent discoveries include the idea that the neurotransmitter noradrenaline impacts the oscillations of neurons in the amygdala, transitioning the brain to a state of heightened arousal, leading to a conditioned expression of fear. Better understanding the neuroanatomy of our behavior opens up the possibility of targeted therapies. We can repair a broken window, and we can repair fear-based bigoty as well.

The shooting of Philando Castile - the amygdala's role in biased fear behavior

What I describe as the bias center includes the amygdala, often described as our fear locus. But in reality, the amygdala has many roles and only in certain circumstances activates to enhance fear based behaviors. this was particularly on display in the traffic stop that ended with Jeronimo Yanez shooting Philando Castille to death. Warning - we are about to watch a violent clip – pay attention to Yanez’s three increasingly panicked statements betraying his subjective and incorrect view that Castile was a threat. The panic continued after, demonstrated by his hysterical shouting. My opinion: (1) Yanez’s amygdala was almost completely in charge and demonstrating a conditioned expression of fear, and (2) because Castile was Black, Yanzs amysala activity incas even more, leading to violent behavior. It’s controversial, so I want to expose the science behind it. Let’s explore the amygdala for a bit.

Unconscious bias-amygdala activation in the brains of white people when flashed a Black face

Outgroup bias can occur at a subconscious level, even for folks who are consciously not prejudiced. In this study, 13 white participants allowed real time reading of their brain activity through fMRI. Importantly they each reported internalized desire to respond without prejudice. When presented a picture of a face for 30 msec, a time course during which most individuals aren’t consciously aware they were shown a face, there was more amygdala activity when shown a Black face than when shown a white face. The amygdala has different roles, but is known as the brain’s fear center. So, especially when we pair this study with the change in the oscillations of the amygdala under conditions of stress, the amygdala may be at the center of, or at least takes part in, unconscious bias and fear based behavior which sometimes leads to violence. With a longer time course of 565 msec, when there was a conscious understanding of a face and its color, the Black-White difference was significantly reduced – presumably automatic attitudes were counteracted by more positive controlled attitudes. This correlated with more activity in the prefrontal cortex and the executive function portions of the brain.

The Amygdala and Fear Based Conditioning

What is it about the amygdala that causes fear of someone outside your self identified demographic? It’s at the center of fear conditioning. Most folks know about Pavlov and his dogs. He paired the sound of a bell, a neutral stimulus, with the taste of food, an unconditioned stimulus, eventually pairing the bell ring, with a conditioned response, salivating as though eating. So it’s this through line, a neutral stimulus eventually pairs with a conditioned response. Fear based violence works in a similar way – the neutral stimulus, the face of a person from an outgroup for example, eventually pairs with a conditioned fear response. What links the two is a lifetime of not exposing yourself in a relevant way to people outside your demographic, and instead experiencing them as the media and your surrounding culture represents them. White people often fear Black people without ever having really gotten to know a single Black person. It’s the ultimate fear conditioning. Much research has pinpointed the encoding of this conditioning to the amygdala.

The case of the missing Amygdala

The best way to determine what a brain structure does, is to damage it then observe the resultant dysfunction. Researchers are able to pharmacologically or electrically silence the amygdala or in other animals, they can be lesioned. In rare instances, humans have damaged or missing amygdalae. The patient known as SM has a rare disease that in her case damaged seemingly the entirety of the bilateral amygdalae and a few other small brain areas. She has little observable dysfunction. , Even complicated cognition such as empathy, memory consolidation, and most emotions are fine. In her case, though, she has a complete inability to recognize, draw, or feel, fear. A stranger held a knife to her throat in a park at night and she never felt afraid. Other patients with damaged amygdalae have trouble detecting fear in others but are able to feel it themselves to a certain extent, so it would seem that in SM’s case the particular type of damage is unusual. So these types of natural experiments are where we get closest to the answer. Fear is an important evolutionary survival tool, and it would seem the amygdala is central to that.

Other roles for the amygdala - not solely fear response

In neurobiology we use the terms “necessary and sufficient” to discuss the functionality of brain structures. Its bn pretty well determined that the amygdala is necessary for the conditioned fear response, and we are circling the idea that it is sufficient. However, fear response is not the only role of the amygdala. The amygdala participates in facial recognition, not just outgroup faces but ingroup as well, and in processing sounds and smells. Memories that are tied to emotions, even positive emotions, are partially encoded by the amygdala. It is also being studied for targeted treatment of addiction and PTSD. The amygdala is not one structure but about six paired nuclei. Each has their own individual functions, not all are well understood, but the best known and most studied are the basolateral nuclei, and they both intake information and output responses. All this to say, amygdalae have dynamic roles. So despite the fact that that activate at unconscious levels and are central to fear-based behaviors and thus at least partially responsible for violence based on bias, different behaviors can be entrained.