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All parts of the brain › Brain chemicals › Serotonin

Where is serotonin made in the brain?

In the brain, serotonin is made mainly by the raphe nuclei, cell groups along the midline of the brainstem: the midbrain, the pons and the medulla oblongata. The upper (rostral) groups send it up to the forebrain, including the cerebral cortex, striatum, amygdala, hippocampus, thalamus and hypothalamus; the lower (caudal) groups send it down to the cerebellum and spinal cord. [1][2][3]

The 3D brain needs JavaScript. The lists below still say where serotonin is made and where it is sent.

Lit: the parts that hold the cells making serotonin (blue) and the parts it is sent to (orange).

Slice

Where serotonin is made is lit in blue, where it is sent in orange. Drag to turn, pinch or scroll to zoom; tap a part or a “light” button to name it on its own; .

Not separate shapes in this atlas; lit: the parts that hold them. Lit in blue: the whole midbrain, pons and medulla oblongata, which hold the raphe nuclei; the cell groups that make serotonin are too small to be shapes in the BodyParts3D model, so nothing is drawn at a guessed point. [1][2]

Lit in orange: the caudate nucleus, putamen, amygdala, hippocampus, thalamus, hypothalamus, septum (septum of telencephalon), cerebellum and spinal cord (central canal), where its fibres end. The fibres themselves are not drawn: the two colours show where the cells are and where they send serotonin, not the routes in between. [4]

Made in: lit in blue

  • Raphe nuclei, lit as the midbrain, pons and medulla oblongata: A ridge of cell groups in the centre of the brainstem, the principal source of the brain’s serotonin: the dorsal and median raphe nuclei in the midbrain, the raphe pontis in the pons, and the raphe magnus, pallidus and obscurus in the medulla oblongata. Many of their neurons, but not the majority, make serotonin. [1][2]

Sent to: lit in orange

  • Caudate nucleus (rostral group): Part of the neostriatum, which the dorsal raphe nucleus projects to. [3]
  • Putamen (rostral group): The other part of the neostriatum, also reached from the dorsal raphe nucleus. [3]
  • Amygdala (rostral group): Reached from the dorsal raphe nucleus. [3]
  • Hippocampus (rostral group): Reached from both the dorsal and the median raphe nucleus. [3]
  • Thalamus (rostral group): Its midline thalamic nuclei are reached from the median raphe nucleus; they are not separate shapes here, so the whole thalamus is lit. [3]
  • Hypothalamus (rostral group): Reached from the median raphe nucleus. [3]
  • Septum (rostral group): Its septal nuclei are reached from the median raphe nucleus. [3]
  • Cerebellum (caudal group): Axons of the lower raphe nuclei end here. [1]
  • Spinal cord (caudal group): Axons of the lower raphe nuclei end here, and the caudal group projects down toward it. [1][2]
  • Not lit as a target: the cerebral cortex, which both the dorsal and the median raphe nucleus reach. Lighting all of it would hide the deeper targets, so it is left grey; see the cortex lobe by lobe on the lobes page. [3]
  • Also reached but inside the parts lit in blue, so not lit apart: the substantia nigra, the ventral tegmental area, the locus coeruleus and the pons itself. [3]

The pathways, as the sources name them

  • Rostral group, the raphe pontis, the median raphe nucleus and the dorsal raphe nucleus, up toward the brain areas of higher function. The axons of these upper nuclei spread out across the entire brain, to many cortical and subcortical structures. [2][1]
  • Caudal group, the raphe magnus, raphe pallidus and raphe obscurus, down toward the spinal cord and brainstem. Their descending fibres reach the spinal cord, where they help control the release of enkephalins that damp pain signals. [2][1]

Good to know

  • Most of the body’s serotonin, about 90%, is made in the gut, not the brain; only 1–2% is found in the central nervous system. [1]
  • Sleep and waking: serotonin from the raphe nuclei mainly promotes wakefulness and holds back rapid eye movement (REM) sleep. [2] See What part of the brain controls sleep?

What it takes part in

Each lit with every part that takes part: What part of the brain controls sleep?

Where it is made, each on its own page: Raphe nuclei.

Sources

  1. Wikipedia: Serotonin
  2. Wikipedia: Raphe nuclei
  3. Wikipedia: Serotonin pathway
  4. BodyParts3D 4.0 (3D model measured on this page), © DBCLS, CC BY-SA 2.1 Japan

Facts describe anatomy and normal function only. The 3D model is the adult male BodyParts3D brain (credits and licence); the cell groups that make serotonin have no shape in it, so the parts that hold them are lit. Real brains vary.