Amygdala Anatomy: 4 Functions of the Amygdala

An amygdala is a cluster of nuclei that prominently govern emotional responses, emotional memory, and decision making. The body contains two amygdalae, one in each hemisphere of the brain. The left and right amygdalae affect the way humans experience cognition, exhibit emotional learning, handle social interaction, and process social input.

The amygdalae contain central nuclei, which include the cortical nucleus, the central nucleus, the medial nucleus, and the basolateral complex (which itself includes lateral nuclei, basal nuclei, and accessory basal nuclei). Intercalated cell clusters encircle the basolateral complex.

Each almond-sized amygdala is located in a temporal lobe of the brain, with one in each hemisphere. The amygdala is surrounded by the cerebral cortex and directly touches the hippocampus and the thalamus. Along with other forebrain structures that border the thalamus and the medial temporal lobe of the cerebrum, the amygdala is considered part of the limbic system.

The amygdala has neural connections to the hypothalamus, the brainstem, the ventral tegmental area, the nuclei of the trigeminal nerve and the facial nerve, the laterodorsal tegmental nucleus, the dorsomedial thalamus, the thalamic reticular nucleus, and the locus coeruleus.

From processing stimuli to regulating emotion, the amygdala plays many crucial roles in the body.

1. 1. Sensory perception: The body's ability to sense smells and pheromones comes from the medial nucleus of the amygdala, and other sensory input and stimuli pass through the central nuclei.
2. 2. Processing emotions: The two amygdalae appear to process different emotions. The right amygdala processes fear-inducing stimuli. It can issue a fearful response that elevates blood pressure, propels heart rate, and releases stress hormones and adrenaline. The left amygdala seems connected to the body's reward-processing system and can process both positive and negative emotions. Dopamine receptors in the left amygdala help make this possible.
3. 3. Memories: The right amygdala has been linked to declarative memory acquisition, which involves facts and data. It also seems to control episodic memory, which includes stories and emotions from past events.
4. 4. Emotional learning: While much of learning is thought to center in the basal forebrain in the frontal cortex, the amygdala does help store memories associated with emotional events, as well as stimuli like smells and tastes. This correlates with synaptic plasticity, where synapses rearrange themselves as neural circuits in the formation and retention of memories.

Given the amygdala's many functions, it can cause problems when damaged. Lesions of the amygdala can change behavior and lead to anxiety disorders or reduced inhibition. The amygdala may impact social anxiety disorder, obsessive-compulsive disorder (OCD), post-traumatic stress disorder (PTSD), and bipolar disorder

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