The mammillary bodies are a pair of small round bodies, located on the undersurface of the

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a v ...

that, as part of the diencephalon, form part of the

limbic system The limbic system, also known as the paleomammalian cortex, is a set of brain structures located on both sides of the thalamus, immediately beneath the medial temporal lobe of the cerebrum primarily in the forebrain.Schacter, Daniel L. 2012. ''Ps ...

. They are located at the ends of the anterior arches of the fornix. They consist of two groups of nuclei, the medial mammillary nuclei and the lateral mammillary nuclei. Neuroanatomists have often categorized the mammillary bodies as part of the posterior part of

hypothalamus The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamu ...

Structure

Connections

They are connected to other parts of the brain (as shown in the schematic, below left), and act as a relay for impulses coming from the

amygdala The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex verte ...

e and hippocampi, via the

mamillo-thalamic tract The mammillothalamic tract (mammillothalamic fasciculus, thalamomammillary fasciculus, bundle of Vicq d’Azyr) arises from cells in both the medial and lateral nuclei of the mammillary body and by fibers that are directly continued from the forn ...

to the

thalamus The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, ...

Function

File:Slide5dd.JPG, Mammillary body Mammillary bodies, and their projections to the anterior thalamus via the mammillothalamic tract, are important for recollective memory. The damage of medial mammillary nucleus leads to spatial memory deficit, according to observations in rats with mammillary body lesions.

Clinical significance

Damage to the mammillary bodies due to

thiamine Thiamine, also known as thiamin and vitamin B1, is a vitamin, an essential micronutrient, that cannot be made in the body. It is found in food and commercially synthesized to be a dietary supplement or medication. Phosphorylated forms of thi ...

deficiency is implied in pathogenesis of

Wernicke–Korsakoff syndrome Wernicke–Korsakoff syndrome (WKS) is the combined presence of Wernicke encephalopathy (WE) and Korsakoff syndrome. Due to the close relationship between these two disorders, people with either are usually diagnosed with WKS as a single syndrome ...

. Symptoms include impaired

memory Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered, ...

, also called

anterograde amnesia In neurology, anterograde amnesia is the inability to create new memories after the event that caused amnesia, leading to a partial or complete inability to recall the recent past, while long-term memories from before the event remain intact ...

, suggesting that the mammillary bodies may be important for memory. Lesions of the medial dorsal and anterior nuclei of the thalami and lesions of the mammillary bodies are commonly involved in

amnesic Amnesia is a deficit in memory caused by brain damage or disease,Gazzaniga, M., Ivry, R., & Mangun, G. (2009) Cognitive Neuroscience: The biology of the mind. New York: W.W. Norton & Company. but it can also be caused temporarily by the use ...

syndromes in humans. Mammillary body atrophy is present in several other conditions, such as

colloid cysts A colloid cyst is a non-malignant tumor in the brain. It consists of a gelatinous material contained within a membrane of epithelial tissue. It is almost always found just posterior to the foramen of Monro in the anterior aspect of the third ve ...

in the third ventricle, Alzheimer’s disease, schizophrenia, heart failure, and sleep apnea. In spite of this the exact function of the mammillary bodies is still not clear.

References

External links