In the early 1800s, a neuroanatomist, Karl Burdach discovered a group of clustered neurons in the brain (Pabba, 2013). He named this cluster the “Amygdala” after the greek word for almond, Amygdale (Britannica, 2021). It was not until the 1930s that scientists began to understand the function of this brain area.
In 1939, Dr. Heinrich Kluver and Dr. Paul Bucy observed a peculiar set of symptoms in Rhesus monkeys after the removal of the amygdala (as well as some parts of the hippocampus and temporal lobe). These monkeys developed dramatically increased sex drives, dysregulating feeding behaviors, and most importantly, a severe lack of fear. This condition was named Kluver-Bucy syndrome (KBS). Since its discovery, KBS has been seen in humans, often due to traumatic brain injury or strokes that damage the amygdala (Ledoux, 2007; Das & Siddiqui, 2020)! Subsequent research on the amygdala in mice corroborated the data from Kluver & Bucy on its relationship with fear responses. In more recent years, neuroimaging studies have been able to correlate human fear responses with activation of the amygdala (Janak & Tye, 2015).
The amygdala has been found to be intimately connected to our emotional regulation and social behavior. As you can imagine, altered functioning of the amygdala is commonly implicated in many psychiatric conditions (Britannica, 2021). By learning more about the functions and underlying circuitry of the amygdala, scientists can develop better therapeutic treatments for those of us with overactive ones!