Amygdala

The amygdala (/əˈmɪɡdələ/; plural: amygdalae; also corpus amygdaloideum; Latin from Greek, ἀμυγδαλή, amygdalē, 'Almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain in complex vertebrates, including humans. Shown in research to perform a primary role in the processing of memory, decision-making and emotional responses (including fear, anxiety, and aggression), the amygdalae are considered part of the limbic system. The regions described as amygdala nuclei encompass several structures with distinct connectional and functional characteristics in humans and other animals. Among these nuclei are the basolateral complex, the cortical nucleus, the medial nucleus, the central nucleus, and the intercalated cell clusters. The basolateral complex can be further subdivided into the lateral, the basal, and the accessory basal nuclei. Anatomically, the amygdala, and more particularly its central and medial nuclei, have sometimes been classified as a part of the basal ganglia. In one study, electrical stimulations of the right amygdala induced negative emotions, especially fear and sadness. In contrast, stimulation of the left amygdala was able to induce either pleasant (happiness) or unpleasant (fear, anxiety, sadness) emotions. Other evidence suggests that the left amygdala plays a role in the brain's reward system.