Editing Hippocampus (section)

====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"/>