Editing Hippocampus (section)

==Other animals==
===Other vertebrates===
Non-mammalian [[vertebrate]]s lack a brain structure that looks like the mammalian hippocampus, but they have one that is considered [[Homology (biology)|homologous]] to it. The hippocampus, is in essence part of the allocortex. Only mammals have a fully developed cortex, but the structure it evolved from, called the [[pallium (neuroanatomy)|pallium]], is present in all vertebrates, even the most primitive ones such as the [[lamprey]] or [[hagfish]].<ref>{{cite journal | vauthors = Aboitiz F, Morales D, Montiel J | title = The evolutionary origin of the mammalian isocortex: towards an integrated developmental and functional approach | journal = The Behavioral and Brain Sciences | volume = 26 | issue = 5 | pages = 535–552 | date = October 2003 | pmid = 15179935 | doi = 10.1017/S0140525X03000128 | ref = refAboitiz2003 | s2cid = 6599761 }}</ref><ref>{{cite book | vauthors = Bingman VP, Salas C, Rodriguez F | date = 2009 | chapter = Evolution of the Hippocampus | veditors = Binder MD, Hirokawa N, Windhorst U | title = Encyclopedia of Neuroscience | pages = 1356–1360 | publisher = Springer | location = Berlin, Heidelberg | doi = 10.1007/978-3-540-29678-2_3158 | isbn = 978-3-540-29678-2 }}</ref> The pallium is usually divided into three zones: medial, lateral and dorsal. The medial pallium forms the precursor of the hippocampus. It does not resemble the hippocampus visually because the layers are not warped into an S shape or enfolded by the dentate gyrus, but the homology is indicated by strong chemical and functional affinities. There is evidence that these hippocampal-like structures are involved in spatial cognition in [[reptile]]s, and in [[fish]].<ref>{{cite journal | vauthors = Rodríguez F, López JC, Vargas JP, Broglio C, Gómez Y, Salas C | title = Spatial memory and hippocampal pallium through vertebrate evolution: insights from reptiles and teleost fish | journal = Brain Research Bulletin | volume = 57 | issue = 3–4 | pages = 499–503 | year = 2002 | pmid = 11923018 | doi = 10.1016/S0361-9230(01)00682-7 | ref = refRodriguez2002 | s2cid = 40858078 }}</ref>

====Fish====
In [[teleost]] fish, the forebrain is everted (like an inside-out sock) with structures that lie on the outside, as contrasted with other vertebrate structures that lie in the interior, next to the ventricles.<ref name="Hegarty2024">{{cite journal |vauthors=Hegarty BE, Gruenhagen GW, Johnson ZV, Baker CM, Streelman JT |title=Spatially resolved cell atlas of the teleost telencephalon and deep homology of the vertebrate forebrain |journal=Commun Biol |volume=7 |issue=1 |pages=612 |date=May 2024 |pmid=38773256 |pmc=11109250 |doi=10.1038/s42003-024-06315-1 |url=}}</ref> One of the consequences of this is that the medial pallium, the hippocampal zone of a typical vertebrate, is thought to correspond to the lateral pallium of a typical fish.<ref>{{cite journal |vauthors=Broglio C, Gómez A, Durán E, Ocaña FM, Jiménez-Moya F, Rodríguez F, Salas C |title=Hallmarks of a common forebrain vertebrate plan: specialized pallial areas for spatial, temporal and emotional memory in actinopterygian fish |journal=Brain Res Bull |volume=66 |issue=4–6 |pages=277–81 |date=September 2005 |pmid=16144602 |doi=10.1016/j.brainresbull.2005.03.021 |url=}}</ref> Several types of fish (particularly goldfish) have been shown experimentally to have strong spatial memory abilities, even forming [[cognitive map]]s of the areas they inhabit.<ref name="Jacobs2003" /> Studies in [[goldfish]] show that damage to both the lateral pallium, and the medial pallium impairs spatial memory coding.<ref name="Givon">{{cite journal |vauthors=Givon S, Altsuler-Nagar R, Oring N, Vinepinsky E, Segev R |title=Lateral and medial telencephalic pallium lesions impair spatial memory in goldfish |journal=Brain Res Bull |volume= 204|issue= |pages=110802 |date=October 2023 |pmid=39492553 |doi=10.1016/j.brainresbull.2023.110802 |url=|doi-access=free }}</ref><ref>{{cite journal | vauthors = Vargas JP, Bingman VP, Portavella M, López JC | title = Telencephalon and geometric space in goldfish | journal = The European Journal of Neuroscience | volume = 24 | issue = 10 | pages = 2870–2878 | date = November 2006 | pmid = 17156211 | doi = 10.1111/j.1460-9568.2006.05174.x | ref = refVargas2006 | s2cid = 23884328 }}</ref> It is not clear if the medial pallium plays a similar role in basal vertebrates, such as [[shark]]s and [[Batomorphi|rays]], or even [[lamprey]]s and [[hagfish]].<ref>{{cite journal | vauthors = Docampo-Seara A, Lagadec R, Mazan S, Rodríguez MA, Quintana-Urzainqui I, Candal E | title = Study of pallial neurogenesis in shark embryos and the evolutionary origin of the subventricular zone | journal = Brain Structure & Function | volume = 223 | issue = 8 | pages = 3593–3612 | date = November 2018 | pmid = 29980930 | doi = 10.1007/s00429-018-1705-2 | ref = Docampo-Seara2018 | hdl-access = free | doi-access = free | hdl = 10347/17636 }}</ref> The dorsolateral pallium of the teleost is considered as homologous to the hippocampus in terrestrial vertebrates.<ref name="Animals2021">{{cite journal |vauthors=Rodríguez F, Quintero B, Amores L, Madrid D, Salas-Peña C, Salas C |title=Spatial Cognition in Teleost Fish: Strategies and Mechanisms |journal=Animals |volume=11 |issue=8 |date=July 2021 |page=2271 |pmid=34438729 |pmc=8388456 |doi=10.3390/ani11082271 |doi-access=free |url=}}</ref> In 2023, the goldfish brain was mapped by molecular parcellization showing that its telencephalon subregions were homogeneous to the hippocampal subfields in the mouse.<ref name="Givon"/>

====Birds====
{{See also|Avian pallium}}
In birds, the correspondence is sufficiently well established that most anatomists refer to the medial pallial zone as the "avian hippocampus".<ref>{{cite journal | vauthors = Colombo M, Broadbent N | title = Is the avian hippocampus a functional homologue of the mammalian hippocampus? | journal = Neuroscience and Biobehavioral Reviews | volume = 24 | issue = 4 | pages = 465–484 | date = June 2000 | pmid = 10817844 | doi = 10.1016/S0149-7634(00)00016-6 | ref = refColombo2000 | s2cid = 22686204 }}</ref> Numerous species of birds have strong spatial skills, in particular those that cache (store) food. There is evidence that food-caching birds have a larger hippocampus than other types of birds and that damage to the hippocampus causes impairments in spatial memory.<ref>{{cite journal | vauthors = Shettleworth SJ | title = Memory and hippocampal specialization in food-storing birds: challenges for research on comparative cognition | journal = Brain, Behavior and Evolution | volume = 62 | issue = 2 | pages = 108–116 | year = 2003 | pmid = 12937349 | doi = 10.1159/000072441 | ref = refShettleworth2003 | s2cid = 23546600 }}</ref>

===Insects and molluscs===
Some types of [[insect]]s such as [[cockroaches]], and [[molluscs]] such as the [[octopus]], also have strong spatial learning and navigation abilities, but these appear to work differently from the mammalian spatial system, suggesting that there is no common evolutionary origin. [[Mushroom bodies]] in insect brains are associated with learning and memory carried out in the mammalian hippocampus.<ref>{{cite journal | vauthors = Mizunami M, Weibrecht JM, Strausfeld NJ | title = Mushroom bodies of the cockroach: their participation in place memory | journal = The Journal of Comparative Neurology | volume = 402 | issue = 4 | pages = 520–537 | date = December 1998 | pmid = 9862324 | doi = 10.1002/(SICI)1096-9861(19981228)402:4<520::AID-CNE6>3.0.CO;2-K | ref = refMizunami1998 | s2cid = 44384958 }}</ref> The brain of the octopus is arranged in a circle of lobes around the esophagus. The vertical lobe has been shown to be involved in forming long term memory, and is seen to be analogous to the mammalian hippocampus and [[cerebellum]], and also to share some functional features of the mushroom bodies in insects.<ref name="Jacobs">{{cite journal |vauthors=Jacobs RE |title=Diffusion MRI Connections in the Octopus Brain |journal=Exp Neurobiol |volume=31 |issue=1 |pages=17–28 |date=February 2022 |pmid=35256541 |pmc=8907252 |doi=10.5607/en21047 |url=}}</ref><ref name="Richter">{{cite journal |vauthors=Richter JN, Hochner B, Kuba MJ |title=Pull or Push? Octopuses Solve a Puzzle Problem |journal=PLOS ONE |volume=11 |issue=3 |pages=e0152048 |date=2016 |pmid=27003439 |pmc=4803207 |doi=10.1371/journal.pone.0152048 |doi-access=free |bibcode=2016PLoSO..1152048R |url=}}</ref>