Hippocampus

Hippocampus
Humans have two hippocampi, one in each hemisphere of the brain. They are located in the medial temporal lobe of the brain. In this lateral view of the human brain, the frontal lobe is at the left, the occipital lobe at the right, and the temporal and parietal lobes have largely been removed to reveal one of the hippocampi underneath.
Hippocampus (lowest pink bulb) as part of the limbic system
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'), also hippocampus proper, is a major component of the brain of humans and many other vertebrates. In the human brain the hippocampus, the dentate gyrus, and the subiculum are the components of the hippocampal formation located in the limbic system. The hippocampus plays important roles in the consolidation of information from short-term memory to long-term memory, and in spatial memory that enables navigation. In humans, and other primates the hippocampus is located in the archicortex, one of the three regions of allocortex, in each hemisphere with neural projections to the neocortex.[1][2][3][4] The hippocampus, as the medial pallium, is a structure found in all vertebrates.[5]

In Alzheimer's disease (and other forms of dementia), the hippocampus is one of the first regions of the brain to suffer damage;[6] 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.[7] Many neurons in the rat and mouse hippocampi respond as place cells: that is, they fire bursts of action potentials when the animal passes through a specific part of its environment.[7] 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.[8]

  1. ^ Creutzfeldt O (27 April 1995). "The allocortex and limbic system". Cortex Cerebri: Performance, Structural and Functional Organisation of the Cortex. doi:10.1093/acprof:oso/9780198523246.003.0009.
  2. ^ Cite error: The named reference Martin2003 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. ^ 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.
  7. ^ a b Eichenbaum H (April 2017). "The role of the hippocampus in navigation is memory". Journal of Neurophysiology. 117 (4): 1785–1796. doi:10.1152/jn.00005.2017. PMC 5384971. PMID 28148640.
  8. ^ Taube JS, Yoder RM (2020). "The impact of vestibular signals on cells responsible for orientation and navigation.". In Fritzsch B (ed.). The Senses; Volume 6: Vestibular System and Balance (2nd ed.). San Diego: Elsevier Science & Technology. pp. 496–511. doi:10.1016/B978-0-12-809324-5.23894-7. ISBN 978-0-12-805409-3.

Hippocampus

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