Amygdala Connections and Functions

Limbic System

• The limbic system is a set of evolutionarily primitive brain structures located on top of the brainstem and buried under the cortex.
• It is involved in emotions, motivations, and survival-related behaviors, such as fear, anger, and sexual behavior.
• It is also involved in feelings of pleasure, such as those experienced from eating and sex.

Amygdala

• The amygdala is connected to association areas of visual, auditory, and somatosensory cortices.
• Its outputs include the hypothalamus and autonomic nuclei in the brain stem.
• Lesions of the amygdala can result in a lack of emotional responses and docility.

Septal Nuclei

• The septal nuclei are located anterior to the interventricular septum.
• They are connected to the hypothalamus and habenular nuclei.
• They are considered the "pleasure zone".

Korsakoff's Psychosis

• Korsakoff's psychosis is a condition characterized by retrograde amnesia (loss of new memories at the time of lesion with retained old memories) and anterograde amnesia (inability to gain new memories).
• It is commonly associated with alcoholism and B1 deficiency.

Temporal Lobe Epilepsy

• The hippocampus is a common focus site in epilepsy and can be damaged through chronic seizures.
• It can also be damaged in diseases such as herpes encephalitis and Alzheimer's disease.

Hippocampus

• The hippocampus is a limbic system structure involved in the formation, organization, and storing of memories.
• It is important in forming new memories and connecting emotions and senses to memories.
• It is a horseshoe-shaped paired structure, one in each cerebral hemisphere.
• It acts as a memory indexer by sending memories to the appropriate part of the cerebral cortex for long-term storage and retrieving them when needed.

Fornix

• The fornix is a C-shaped group of fibers connecting the hippocampus with the mammillary body.
• It consists of 2 fimbria, 2 crus, 1 body, and 2 columns.
• It is an important component of the Papez circuit.

Limbic System Structures

• Cortical structures: limbic lobe, hippocampal formation, septal areas, prefrontal area
• Subcortical structures: hippocampus, amygdala, anterior thalamic nuclei, hypothalamus, fornix, habenular nuclei, olfactory system
• Olfactory system: structures involved in smell and smell-related memories

Hippocampal Formation

• The hippocampal formation consists of the hippocampus, dentate gyrus, subiculum, entorhinal area, and induseum griseum.

Amygdala Function

• The amygdala is involved in fear, emotions, anger, and hormonal secretions.