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. Author manuscript; available in PMC: 2018 Mar 22.
Published in final edited form as: Annu Rev Med. 2009;60:355–366. doi: 10.1146/annurev.med.60.042307.110802

Figure 1.

Figure 1

Central serotonergic pathways, effects, and drugs. In the central nervous system (CNS), serotonin is almost exclusively produced in neurons originating in the raphe nuclei located in the midline of the brainstem. These serotonin-producing neurons form the largest and most complex efferent system in the human brain. The most caudal raphe innervate the spinal cord, while the more rostral raphe, the dorsal raphe nucleus and the medial raphe nucleus, innervate much of the rest of the CNS by diffuse projections. Indeed, virtually every cell in the brain is close to a serotonergic fiber, and nearly all behaviors as well as many other brain functions are regulated by serotonin. Not surprisingly, serotonin receptors and transporters are a major focus of CNS drug development, and many current medications modulate serotonin neurotransmission. 5-HT, serotonin; MAOI, monoamine oxidase inhibitor; SSRI, selective serotonin reuptake inhibitor.