A circular, complex system of NERVE pathways in the middle of the BRAIN. This connected cluster of neuronal nuclei is involved in the working of the AUTONOMIC NERVOUS SYSTEM, helping to control the expression of instinct and mood in activities of the motor systems and the ENDOCRINE GLANDS of the body. The brain regions involved include the amygdala (almond-shaped basal ganglia deep in each cerebral hemisphere), and the HYPOTHALAMUS. If the limbic system is impaired by injury or disease, the person may suffer abnormal emotional responses such as unprovoked rage, unreasonable fear and anxiety, depression, greater-than-normal sexual interest, and crying or laughing for no good reason.