Hippocampus

This article is about the section in the brain. For the fish genus Hippocampus, see Seahorse. For the mythological creature Hippocampus, see Hippocampus (mythology). For other uses, see Hippocampus (disambiguation).

Hippocampus
Hippocampus (lowest pink bulb) as part of the limbic system
Animation of both hippocampi in humans, located in the medial temporal lobes of the cerebrum
Details
Part ofTemporal lobe
Identifiers
Latinhippocampus
MeSHD006624
NeuroNames3157
NeuroLex IDbirnlex_721
TA98A14.1.09.321
TA25518
FMA275020
Anatomical terms of neuroanatomy

The hippocampus (pl.: hippocampi; via Latin from Greek ἱππόκαμπος, 'seahorse') is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system, and plays important roles in the consolidation of information from short-term memory to long-term memory, and in spatial memory that enables navigation. The hippocampus is located in the allocortex, with neural projections into the neocortex, in humans[1][2][3] as well as other primates.[4] The hippocampus, as the medial pallium, is a structure found in all vertebrates.[5] In humans, it contains two main interlocking parts: the hippocampus proper (also called Ammon's horn), and the dentate gyrus.[6][7]

In Alzheimer's disease (and other forms of dementia), the hippocampus is one of the first regions of the brain to suffer damage;[8] short-term memory loss and disorientation are included among the early symptoms. Damage to the hippocampus can also result from oxygen starvation (hypoxia), encephalitis, or medial temporal lobe epilepsy. People with extensive, bilateral hippocampal damage may experience anterograde amnesia: the inability to form and retain new memories.

Since different neuronal cell types are neatly organized into layers in the hippocampus, it has frequently been used as a model system for studying neurophysiology. The form of neural plasticity known as long-term potentiation (LTP) was initially discovered to occur in the hippocampus and has often been studied in this structure. LTP is widely believed to be one of the main neural mechanisms by which memories are stored in the brain.

In rodents as model organisms, the hippocampus has been studied extensively as part of a brain system responsible for spatial memory and navigation. Many neurons in the rat and mouse hippocampus respond as place cells: that is, they fire bursts of action potentials when the animal passes through a specific part of its environment. Hippocampal place cells interact extensively with head direction cells, whose activity acts as an inertial compass, and conjecturally with grid cells in the neighboring entorhinal cortex.[citation needed]

  1. ^ Cite error: The named reference Martin2003 was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference Amaral2007-1a was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference Amaral2007-1b was invoked but never defined (see the help page).
  4. ^ Bachevalier J (December 2019). "Nonhuman primate models of hippocampal development and dysfunction". Proceedings of the National Academy of Sciences of the United States of America. 116 (52): 26210–26216. Bibcode:2019PNAS..11626210B. doi:10.1073/pnas.1902278116. PMC 6936345. PMID 31871159.
  5. ^ Bingman VP, Salas C, Rodriguez F (2009). "Evolution of the Hippocampus". In Binder MD, Hirokawa N, Windhorst U (eds.). Encyclopedia of Neuroscience. Berlin, Heidelberg: Springer. pp. 1356–1360. doi:10.1007/978-3-540-29678-2_3158. ISBN 978-3-540-29678-2.
  6. ^ "Search Results for ammon's horn". Oxford Reference. Retrieved 9 December 2021.
  7. ^ Colman AM (21 May 2015). "dentate gyrus". A Dictionary of Psychology. Oxford University Press. doi:10.1093/acref/9780199657681.001.0001. ISBN 978-0-19-965768-1. Retrieved 10 December 2021.
  8. ^ Dubois B, Hampel H, Feldman HH, Scheltens P, Aisen P, Andrieu S, et al. (March 2016). "Preclinical Alzheimer's disease: Definition, natural history, and diagnostic criteria". Alzheimer's & Dementia. 12 (3): 292–323. doi:10.1016/j.jalz.2016.02.002. PMC 6417794. PMID 27012484.