Mechanisms and Functions of Serotonin Neuronal Systems

Serotonin (5-hydroxytryptamine) was discovered to be present in brain in 1953 and soon thereafter was correctly postulated to serve as a neurotransmitter or neuromodulator. The original mapping of serotonin neurons in the central nervous system (CNS) in the 1960s provided some insight into their possible physiological roles.1 The development of drugs that modify serotonin function in specific ways has helped in understanding the numerous functions of serotonin neurons and their operation.