The amygdala and emotion are tied together because the amygdala is the part of the brain responsible for interpreting the five senses and producing an emotional response. A body uses emotion to direct it in key activities, such eating, drinking, and sexual reproduction. In evolutionary terms, the amygdala and emotion are responsible for the continued survival of an individual and its species because the amygdala processes fight or flight responses in harmful situations.
A connection between the amygdala and emotion were learned about through the study of patients with lesions in the temporal lobe that had changes in emotional responses and expression. Bilateral lesions on the amygdala used to be purposefully inflicted on psychotic patients in an attempt to calm them down and relieve their suffering. Researchers now use functional imaging and other brain scanning techniques to study the amygdala and emotion. New information is being obtained regarding the role of amygdala in anxiety, obsessive compulsive disorder, and schizophrenia.
Historically, fear has been the emotion most tied to the amygdala. Another role of the amygdala and emotion is the acquisition of food and water. Emotion is tied to food and water intake because fear evolved as a survival mechanism for danger, a situation that could be encountered naturally when hunting and finding safe water sources. The amygdala and emotion are also associated with motivation and the use of rewards for learning.
Emotional memory is the unconscious recollection of emotions tied to a specific remembered event or piece of information. The amygdala is part of the process that records and stores emotional memory. Learning processes use emotional memory to remember information, and studies have shown that associating something with an emotion aids in later recollection.
The amygdala processes all forms of sensory information, including sight, sounds, touch, smell, and taste. It tells the body how to react, causing it to quickly run away when danger is detected, or making the body freeze in place from fear. Aggression is another emotion known to be regulated by the amygdala, as may be maternal instincts.
Located within the temporal lobe near the uncus, the amygdala is almond shaped. It is part of the limbic system and is connected to the hypothalmus by the stria terminalis, a connection that runs parallel to the fornix. There is a dual sensory input to the amygdala, with one side running to it directly and the other first stopping for processing within the main cortex. Emotional responses are from the second path, while the first path is a signal that tells the body to quickly react to its situation.
