Tuberomammillary nucleus explained

Tuberomammillary nucleus
Latin:	nucleus tuberomamillaris
Width:	300px
Ispartof:	Hypothalamus
Acronym:	TMN

The tuberomammillary nucleus (TMN) is a histaminergic nucleus located within the posterior third of the hypothalamus. It is part of the tuber cinereum. It largely consists of histaminergic neurons (i.e. histamine-releasing neurons). It is involved with the control of arousal, learning, memory, sleep and energy balance.

Efferents

The tuberomammillary nucleus is the sole source of histamine pathways in the human brain. The densest axonal projections from the tuberomammillary nucleus are sent to the cerebral cortex, hippocampus, neostriatum, nucleus accumbens, amygdala, and other parts of the hypothalamus.^[1] The projections to the cerebral cortex directly increase cortical activation and arousal, and projections to acetylcholinergic neurons of the basal forebrain and dorsal pons do so indirectly, by increasing the release of acetylcholine in the cerebral cortex.

Notes and References

1. Book: Molecular Neuropharmacology: A Foundation for Clinical Neuroscience. Malenka RC, Nestler EJ, Hyman SE. McGraw-Hill Medical. 2009. 9780071481274. Sydor A, Brown RY. 2nd. New York. 175–176. Chapter 6: Widely Projecting Systems: Monoamines, Acetylcholine, and Orexin. Within the brain, histamine is synthesized exclusively by neurons with their cell bodies in the tuberomammillary nucleus (TMN) that lies within the posterior hypothalamus. There are approximately 64000 histaminergic neurons per side in humans. These cells project throughout the brain and spinal cord. Areas that receive especially dense projections include the cerebral cortex, hippocampus, neostriatum, nucleus accumbens, amygdala, and hypothalamus. ... While the best characterized function of the histamine system in the brain is regulation of sleep and arousal, histamine is also involved in learning and memory ... It also appears that histamine is involved in the regulation of feeding and energy balance..