Talk:Hippocampus/Archive 1

Issues
You may want to revise the section about the hippocampus being phylogenically old. In fact, all of cortex is phylogenically recent. The hippocampus develops from telencephalic tissue, the most phylogenically recent section of neural tissue. The hippocampus is phylogenically "older" than neocortex, but midbrain and hindbrain regions (pons, medulla, etc) likely evolved much earlier.

I think the phylogenetic history of the hippocampus should be extended and moved to its own section. "Emergence from the archipallium" is a bit technical. Maybe this needs some introductory explanation. Washington irving 10:15, 26 Feb 2004 (UTC)

Maybe, we should use more accessible phrases such as "more recent in evolutionary terms" rather than "phylogenetically younger".

The component parts of the hippocampus need to be described. I can't find any references to presubiculum, subiculum, prosubiculum, or the CA segments.

Hippocampus and penis size
Does anyone have any cites for the claim about the relationship between hippocampus and penis length? If so it should be expanded and made more clear if not we should delete the reference to this somewhat dubious sounding claim.

Hippocampus
Is there any physical link between the Hippocampus and the Hypothalamus? That is, are they or aren't they indepedent of one another? --Tothebarricades.tk 03:56, May 12, 2005 (UTC)
 * There is a physical link between both. There are a number of fiber track that run through the lateral hypothalamus to the fornix and into the hippocampus. This physical data has also been shown behavioraly through fear conditioning studies. Goferwiki 10:18, 16 Jun 2005 (UTC)
 * As the above editor says, there is a very strong link. An important function of the hippocampus seems to be to regulate the Hypothalamo-Pituitary-Adrenal (HPA) axis. Not only are there the neuronal connections stated above, but also connections to the paraventricular nucleus of the hypothalamus. This is an area which releases the hormones CRH and AVP into the pituitary, thus causing the release of ACTH into the bloodstream. ACTH causes the release of glucocorticoids from the adrenal cortex which negatively feed back to the HPA axis. The hippocampus is very rich in glucocorticoid receptors (GR) and is thought to take part in the regulatory feedback process. GR activation has been shown to have many effects on hippocampal plasticity (something I work on). There isnt enough about the hippocampus's role in stress in this article at the moment - I hope to add more shortly. Povmcdov 14:11, 12 June 2007 (UTC)

Anatomy note
Is it sure that the hippo. is part of cortex or subcortex? Anyone of you could answer to this (trivial) question, please? --Eletto


 * The CA fields, dentate gyrus, and subiculum are classified as allocortex. The presubiculum, parasubiculum, and entorhinal cortex are classified as periallocortex. Much of the rest of the corical mantle is isocortex (there are a few other regions, like parts of orbitofrontal and piriform that are not isocortical, as I recall). 128.197.81.223 20:50, 13 July 2006 (UTC)
 * Oops, that was me. I wasn't logged in apparently. Digfarenough 20:51, 13 July 2006 (UTC)

Nice job, indeed. Thanks a lot. --Eletto 03:55, 20 September 2006 (UTC)

I added a section on some details of hippocampal anatomy, but I'm not sure how much detail should be included as this is an encyclopedia, not a neuroscience textbook. Anyone know what the limit is? I could write much more about electrophysiology of hippocampus as well as current models about its function and anatomy and so forth and can provide good references for both the new information and for information already mentioned in the article... Digfarenough 02:24, 17 August 2005 (UTC)
 * Nice work, Digfarenough. My philosophy on this is to write as much as I can. Another user and I are both heavily reworking cerebellum right now. Head over there and you will see the amount of detail we've included. Be as thorough as you can! Semiconscious  ( talk  · home) 05:45, 17 August 2005 (UTC)

Very big POV problem
I came to this page looking for information on the hippocampus, as in the creature from Greek mythology, and was very disappointed to find an entire article dedicated wholly to one rather obscure use of the word. While the usage in medicine/anatomy is certainly important, it has absolutely nothing to do with what most people understand a hippocampus to be. The only information on this page relating to the mythic hippocampus is "In Greek mythology, the hippocampus ("horse-like sea monster") was a mythical monster, half horse, half sea-monster. One of them pulled Poseidon's chariot. It looked like a horse with the rear part resembling a fish or dolphin." This page gives the overall impression that the medical usage is the more important one and therefore deserves top-billing, while in truth neither usage is "more important" than the other, and the mythological usage is doubtless by far the most common outside of medical circles.

Either the medical/anatomical usage needs to be moved to its own page (as the mythological usage dramatically overshadows the medical usage), or all uses need to be moved to their own pages, leaving this page as a disambiguation. --Corvun 11:42, August 22, 2005 (UTC)
 * Admittedly I'm a neuroscientist, so I am biased, but I'm sure your claim that "the mythological usage dramatically overshadows the medical usage". In Greek mythology, hippocampus is a minor character, whereas in the brain the hippocampus is one of the most important structures about which every student in biology, psychology, etc. knows, as it is what is responsible for formation of memories. A quick Google check shows that the words "hippocampus brain" return about 675,000 hits, whereas "hippocampus Greek" gives only about 22,400 and "hippocampus mythology" only about 5,830. If you can find evidence that this 30:1 ratio of usage is incorrect, then I'd love to see it.

Anyway, the English transliteration for the Greek mythological creature is "hippocamp", correct? So shouldn't that page include the piece about the Greek mythology version, and not "hippocampus"? Semiconscious ( talk  · home) 15:25, 22 August 2005 (UTC)


 * I'm aware of the importance of the hippocampus in medicine/anatomy (including psychology). I may not be a neuroscientist, but I took biology and psychology classes in school and am therefore aware of the important role that the hippocampus plays.  But aside from those people who actually end up pursuing a career in medicine, I sincerely doubt that anyone first thinks of this usage when hearing the word "hippocampus".  All a quick Google search shows is that there are more articles on the part of the brain than on the mythological creature, which is expected since an extinct mythology is finite and experiences few if any new additions whereas the field of medicine is in constant, almost violent flux.


 * As far as the issue of linguistics is concerned, whether or not the English transliteration should be rendered as "hippocamp" isn't very relevant, considering this is not how the word is generally transliterated. However, names in mythology often have important allegorical, metaphorical, or even literal meaning which is important to the understanding of that which they refer to; names in medicine have no such importance.  Whether hippocampus or hippocamp, the name is significant, whereas the part of the brain known as the hippocampus could just as easily be called the figgle-foogle and mean exactly the same thing.  The term is completely insignificant in that context.  Obviously, this isn't about which term is "correct".  They are both correct and should be presumed of equal import if we are not to support a particular POV.  The only issue is which usage is more common, and outside the field of medicine/anatomy, the usage that takes up the bulk of this page is effectively non-existent. --Corvun 02:01, August 23, 2005 (UTC)


 * You're arguing that the mythological name is significant (more than the well-defined, immutably named anatomical definition), yet you also are claiming that the English transliteration isn't important and it doesn't matter if it's "hippocampus" or "hippocamp". You can't argue both sides simultaneously, and a wikipedia search can't redirect a user to the nebulous quality embodied by the Greek mythological character. You argue that a Google search only proves that the anatomical definition has more references. Well if there are far more references, then wouldn't that make it a more likely Wikipedia search as well? I've given at least one qualitative piece of evidence, and all you've countered with is a personal feeling regarding what you think people would probably be searching for. That's not evidence.
 * This is all a moot point right now anyway as there isn't even an article on the Greek mythological creature. There's a hippocampus_(mythology) page that redirects here, and there's the List_of_Greek_mythological_creatures that has the name in a list. This can't be more important creature in mythology than a currently heavily-studied, heavily-taught important piece of anatomy. If you can't argue against my attempt at quantification, and continue to counter with a belief that is not-provable, I don't really know what else to say. Semiconscious  ( talk  · home) 03:07, 23 August 2005 (UTC)


 * You know very well I wasn't arguing "both sides" of anything, and your claim that I was is a distortion that completely ignores the issue raised by equivocating transliteration with etymological definition -- two very, very different things. I'm not here to provide "evidence" for anything.  All I'm saying is that there definitely needs to be a separate page for Hippocampus (anatomy), and possibly needs to be a separate page for Hippocampus (mythology) even if it's a stub.  If we can't agree on which usage is more common, it seems sensible to split the difference per my suggestion.  Keeping a page on Hippocampus filled with information on a single, obscure use of the term used nowhere outside of medicine and anatomy should not be an option.  And if you feel the same is true for the Hippocampus from mythology, then obviously this page needs to be a disambiguation rather than being used for one or the other.  --Corvun 04:12, August 23, 2005 (UTC)


 * Clearly I don't know very well you weren't arguing both sides of anything. If it had been clear, I wouldn't have said it. What purpose do I have to lie here? If you're not here to provide evidence for anything, then we aren't getting anywhere, are we? You seem to be arguing two sides of a similar point. You aren't giving any information beyond "I think my way is better" which is not a way to make a convincing point. I'm not saying I don't think there shouldn't be a hippocampus (mythology) article &mdash; of course there should be &mdash; I just think it's such a minor definition compared to a topic that is overwhelmingly researched by people of all walks of life and scholarly interest.
 * From what I've shown, the two topics seem to be far from "equal import" as you say. I think the top of the current, anatomical hippocampus page should have a link to "hippocampus (disambiguation)" under the main header. But then again, I don't really care about this; I just think you're incorrect in your statement and acting rather illogically by not offering any proof and arguing based upon your feelings. If you want to track down all the pages that reference the anatomical hippocampus and relink them to hippocampus (anatomical), and write a hippocampus (mythology) page, and then make the hippocampus page a disambiguation page, then we should wait to get others' input, perhaps taking this to arbitration. Numbers are important here, and I've tried to offer some. We're not going to get anywhere, so I'm curious to hear what the Wikipedia powers-that-be think of this. What do you say Mr. Corvun? Semiconscious  ( talk  · home) 17:41, 23 August 2005 (UTC)
 * Semiconscious, you went ahead and made the argument I decided against making when I first saw Corvun's claims. After some thought, I decided against it, as it's hard to say which usage of the word is more common, since the groups who use the different meanings don't seem to overlap much. Personally I know a fair amount of greek mythology and I don't recall ever hearing about the Hippocampus, but that doesn't mean anything. Corvun's argument that the name of the brain region is unimportant but that the mythological beast's name really matters is quite silly, but his point about the creature having only a single line at the bottom of this long article still stands. Because this article also mentions a third and fourth usage of the term, for the seahorses and a Harry Potter character, apparently, I think a disambiguation page is called for as the best solution. Furthermore, because, after years of wikipedia being up, the anatomical term has developed into a full article while the mythological term remains three sentences, I think it's fair to let the anatomical term keep the main Hippocampus entry. I think that reflects a general agreement that the anatomical term is the primary meaning in use these days. Digfarenough 13:18, 25 August 2005 (UTC)


 * Herein lies the POV problem. Semiconscious, the point I was making, which in your over-eagerness to "debate" you completely missed, is that neither use of the term is "more correct".  Digfarenough, of course my argument that the name of the brain region is unimportant is silly, and so by intent.  The both of you seem to be immersed in a sea of peripheral issues and are unable to stand back and look at things with a NPOV.  It is not our place to decide which usage is more important.  Deciding that the anatomical term is the "primary meaning" and that "it's fair to let the anatomical term keep the main Hippocampus entry" is POV.  This is the big POV problem.  This is why I didn't just make a separate disambiguation page to begin with, because the disambiguation page belongs in this namespace. --Corvun 03:50, August 26, 2005 (UTC)


 * The more common usage for hippocampus is the anatomy definition by far. Even the dictionaries agree (both the dictionary dictionary.com and the Oxford dictionary), never mind the numbers on Google which Semiconscious has already quoted. If anything, this page should stay and any other pages such as hippocampus (mythology) should be linked off this page or hippocampus (disambiguation). I expect that the vast majority of people doing a search for the word "hippocampus" would be looking for the brain structure. It's like the article for Sydney - it obviously should be about the city of Sydney in Australia, therefore there is a small line at the top for Sydney (disambiguation) - instead of having the main page of Sydney be a disambiguation page itself for Sydney, Australia and other meanings of Sydney. That's the way to do it. Alex.tan 19:41, August 26, 2005 (UTC)


 * Alex.tan: thanks for the info. This is the exact point I was trying to make. Corvun, I understand the point you have been repeatedly making, despite your somewhat rude indication otherwise (e.g., "in your over-eagerness to 'debate' you completely missed"). In my last comment I suggested exactly the solution Alex.tan is proposing now. I'm not sure why I'm getting this slightly hostile reaction from you. This is not an instance of non-NPOV, no matter how many times you say it is. There are many other pages that do exactly what Alex.tan and I suggest, hence the existence of disambiguation pages on wikipedia.
 * Anyway, I've now created a hippocampus (disambiguation) page since you wouldn't comment on this idea and chose instead to just kept reiterating the same point. If you still disagree or just keep making the same argument, I will request arbitration and we can take this to a vote, because we're just going back and forth at this point and you don't seem to be taking any steps to fix the situation or address any of the stronger counter-arguments. I really am sorry that I seem to be upsetting or annoying you; I've tried to be calm, rational, and address your arguments and apologize if I'm giving you the impression that I'm not understanding you. Semiconscious  ( talk  · home) 21:49, 26 August 2005 (UTC)


 * And yet again, Wikipedia's NPOV policy has been flushed down the toilet. And people still wonder why Wikipedia is the laughing stock of the internet.  --Corvun 22:34, August 26, 2005 (UTC)


 * You are a very confusing person. What's going on here; why are you being so hostile and negative? I am really working to resolve this with you, so please help me out. Where in the NPOV policy page does it state that every topic with multiple meanings must point to a disambiguation page, despite wide disparity in usage between the two terms? I've read and reread the thing, and I can't find anything to that extent. If you show me where in the policy it states I am wrong, I will back down and stand by your side.
 * And where does "the laughing stock of the internet" thing come from? Semiconscious  ( talk  · home) 23:09, 26 August 2005 (UTC)

Consensus seems to be that this page should be about the anatomical entity, and that remaining meanings, including Corvun's mythological creature, should be disambiguated from it. There is no violation of NPOV here - the only problem is priorisation. This kind of problem is typically solved by community consensus. I've seen these debates on several other pages, and it is always a matter of emphasis. I thoroughly disagree with the "laughing stock of the internet" appellation. Apart from being wrong (Wikipedia is heavily cited, even by the reliable news agencies) it also reflects a massive misunderstanding of the power of Wiki in general. I think a retraction would be appropriate. JFW | T@lk  21:52, 27 August 2005 (UTC)

Im probably a bit late for this - but you say the hippocampus region is only important if you are persuing medicine? You said yourself you learned about it in psychology, and knowledge of it is extremely important in many other fields. If you are going to say that, then who aside from a greek mythologist would need to know what hippocampus creature was? I think learning and memory is a more important part of the world today than greek mythology is. This region of the brain is responsible for you knowing what the hippocampus mythological creature is.thuglasT 23:22, 25 February 2007 (UTC)

One other late point to add is that the name hippocampus does have a meaning and purpose in its medical/anatomical usage as well. In coronal sections, the hippocampus really does look a bit like a sea-horse. Names in anatomy aren't arbitrary.

Location/Image
I think it would be good if someone could add to the caption of the first picture: is this a view from below or above, and where is the front? AxelBoldt 06:48, 18 May 2006 (UTC)
 * Done. --David Iberri (talk) 19:03, 18 May 2006 (UTC)

Merge from cornu ammonis
Cornu ammonis is another name for the hippocampus and is used to identify its different regions. Besides the few other bits of info on that article, is there much more to say? If not, I propose that info be merged here. --David Iberri (talk) 02:21, 24 May 2006 (UTC)


 * Hm... I can't think of any reason not to merge it here and redirect. I don't recall the last paper I read that made a major distinction between cornu ammonis and hippocampus (except, I suppose, for some anatomy papers where the authors want to be very clear). Given that the dentate gyrus only sends outputs to the hilus/CA4 and CA3 and that, from a gross anatomical perspective, they are basically one unit, I support merging. Digfarenough 23:11, 12 July 2006 (UTC)


 * Actually, I have a better idea. I was just writing up some more detail about the hippocampal subregions and it occurred to me that it may end up having more detail than the actual hippocampus article should have. Perhaps, instead, we should include only a simple description of the connectivity and such of the subregions on this page, then put more detail about CA1-3 or 4 on the cornu ammonis page, expand the dentate gyrus page, and then link to those two from this page. Probably should expand the subiculum too and include that. I don't know the subiculum terribly well though, and I don't know a lot about interneurons in any of these areas, so I may need assistance with some of the detail. I'll finish writing up the CA1-4 info tonight and put it up tomorrow. I think that given how well studied the hippocampus is, there should be plenty of information to spread across the pages. However, if you think we should put it all here at first until it gets too long, I'd also support that (but when it does get too long, I think the cornu ammonis page is a good place to put some of the information). Digfarenough 00:13, 13 July 2006 (UTC)


 * I like your idea of giving an overview here and then linking elsewhere for details. But I'm wondering whether the subfields should be discussed at Cornu ammonis or whether CA should just redirect to Hippocampus. I'm leaning towards the latter because of the synonym issue. We could put the detailed CA anatomy at, say, Hippocampal subfields. What do you think? --David Iberri (talk) 14:20, 14 July 2006 (UTC) P.S. Great additions over at Cornu ammonis.


 * I think the Hippocampal subfields article is a good idea. Since I already discussed the hilus/CA4 on the CA page, which is more often considered part of the dentate gyrus, it makes sense to go ahead and add a list of the strata in DG and a new subfield entry for the fascia dentata. So Cornu ammonis should probably be moved to Hippocampal subfields. Here's a question though: should the subiculum be discussed on Hippocampal subfields? I'm not as familiar with it so I don't have much to say about it. In my mind, the terms go as follows. The dentate gyrus contains the fascia dentata and the hilus. The hippocampus proper contains fields CA1 through CA3. The subiculum is just the subiculum (the presubiculum and parasubiculum are poorly named, as they are quite different than the subiculum). The hippocampal formation then contains the dentate gyrus, the hippocampus proper, and the subiculum. Cornu ammonis contains CA1 through CA4 if one goes by Lorente de No's convention. So in a sense there's no neat and clean way to separate these things out, as there's a fair bit of overlap in many naming conventions. I guess the easiest thing to do is, on the hippocampus page, give a brief breakdown of the hippocampus into DG, CA1-3, and Subiculum (letting CA4 be part of DG), and have that link to a main article called Hippocampal subfields. Whew.. that was a lot... Digfarenough 18:24, 14 July 2006 (UTC)


 * That's my understanding of the anatomy too. Regardless of the overlap, which is probably unavoidable, I support the organization of articles you suggested. Also, to answer your question, I'd give the subiculum its own article and reserve Hippocampal subfields for CA1-4. Cheers, David Iberri (talk) 20:00, 14 July 2006 (UTC)


 * I've gone ahead and done the move to Hippocampal subfields, with a brief note there about Subiculum that links to its main article. I am just about to make a few more changes to reflect the new title and will make some slight changes on this article to reflect the move. If you care to help out in an easy way, would you mind helping me go through the pages that linked to Cornu ammonis and making them redirect to hippocampus? I'm not sure how much time I have right now, so if you could take a look when you get a chance, I'd be much obliged. Otherwise I'll get to it at some point this weekend. Digfarenough 20:24, 14 July 2006 (UTC)


 * I'm a bit busy at the moment, but will chip in when I get a chance. Cheers, David Iberri (talk) 06:29, 16 July 2006 (UTC)


 * (dropping back on the indentation). 'Tis no problem, I just redirected cornu ammonis to the hippocampus article and that took care of all the links. My guess is that it's safe to just leave it like that. Digfarenough 17:41, 16 July 2006 (UTC)

Reproductive cycle?
On June 8 2006, an IP user added the claim "The hippocampus also plays a vital role in the reproductive cycle." I am not familiar with this claim. Does anyone have a reference for it? This IP address was apparently warned twice for vandalism a few days later (and vandalized the amygdala article the same day as this addition), which I take as further evidence to question this addition. I will remove it pending a reference. Digfarenough 20:57, 13 July 2006 (UTC)


 * I've never heard this claim before. A PubMed search for hippocampus reproductive cycle gives only a handful of results. --David Iberri (talk) 14:37, 14 July 2006 (UTC)

It is not directly related, this comment should be removed. People with damaged hippocampus regions function very normally, they just forget stuff cant form new explicit memories. thuglasT 23:24, 25 February 2007 (UTC)

Hormonal issues?
I recall distinctly from research a couple of decades ago that hippocampectomised Sprague-Dawley rats exhibited elevated [3x normal] levels of ACTH, thus implicating the hippocampus in a basic feedback mechanism. I've seen nothing since then following this issue, nor do I see anything on these pages discussing [what may be]the more basic functionality of the hippocampus, particularly in its relation to hypothalamic function. It may also be that having abandoned that vocational path after my degree, I've missed further work in that area. Obviously, the expected behavioural effects of this expected elevated ACTH level does not seem to be present in humans, were the results consistent with those reports. Comment, please? —Preceding unsigned comment added by Nyuszika45 (talk • contribs)


 * I can only comment, can't really answer your questions as ACTH-related matters (and molecular things in general) are outside my area of expertise. The hippocampus these days is generally accepted to be primarily involved in episodic memory (especially in humans, but in animals too). The dorsal half or so of the hippocampus receives a lot of spatial and sensory input, so it is thought to primarily represent spatial memory (but more and more the spatial memory is shown to be modulated by cognitive demands of tasks). Ventrally, the hippocampus is more closely associated with parts of the amygdala and seems to be related to fear conditioning, among other things. That, I think, is where the link to ACTH would come in, as fear is clearly related to stress, and stress in general has been shown to have effects on the hippocampus (e.g. reducing levels of neurogenesis in the dentate gyrus). In the past couple decades it seems that the focus has gone from the hippocampus just being yet another structure in the limbic system (i.e. Papez circuit sort of things) to being a significant structure in memory (episodic and, to a lesser extent, emotional). To summarize: although there are still researchers examining the sort of thing you mention, it seems to me that the bulk of the field has been concentrating on more general memory aspects (but that may only be because that's the research I do) so there is less emphasis on stress in general. Certainly if you know of relevant research, it would be worth adding to the article. digfarenough (talk) 16:24, 30 September 2006 (UTC)

In 1972, E. Endroczi’s work, “Limbic System, Learning and Pituitary Adrenal Function” was published by Akademai Kiado in Budapest. This work cited not just Endroczi’s work but other contributions prior to this date in establishing evidence pertinent to his research and that supportive work predating the book. Endroczi’s work showed quite different, often perseverative behaviour of rats with extensive hippocampal lesions. Concurrently, the work reviewed showed marked effects of ACTH infusion in facilitating shuttle-box learning. However, the most interesting aspect was the demonstration that hippocampectomised rats demonstrated a significantly higher level of plasma corticosterone than control rats, as well as the elimination of the normal diurnal fluctuations. When tested for exploratory activity, the hippocampectomised rats showed considerably more activity than controls, but this active state was characterised as more perseverative than exploratory. The hippocampectomised rats showed a significant deficit in passive avoidance learning. It is interesting that normal [non-treated or sham-operated] rats given various doses of corticosterone and hydrocortisone 30 to 120 minutes prior to passive avoidance learning sessions performed significantly better than hippocampectomised rats.

While much of this early work indicates a clear impact of hippocampal ablation on learning in simple tasks and routine behaviour, the increased routine [but not directive] activity seems indicative of a state where information is not processed and while the corticosterone levels may infer heightened activity levels, the actual behaviour is less focused than that of normal controls.

At the time, I hazarded an hypothesis that emphasised the consideration of heightened activity and commensurately decreased perceptual acuity as being implicated in the learning deficits displayed by hippocampal rats. However, the NIH did not seem to agree at the time. I have not followed up on this hypothesis or the others that might come to mind considering a potential learning-hormonal relationship. Knowing that there are effects of hormonal states that confound learning abilities, it might be postulated that hippocampal ablations generate confounding conditions. However, I’m sure that this issue has been thoroughly examined in the years since I did this work. So, while I am not aware of the answers, that does not mean that this question has not been considered. It is also obvious from the extensive work done with human subjects having accidental hippocampal damage that serious short-term memory function virtually disappears with hippocampal damage. However, I have not seen anything on hormonal states of hippocampal damage patients.Nyuszika45 01:58, 23 November 2006 (UTC)Douglas Schulek-Miller


 * There is some stong evidence that the hippocampus feeds back to the HPA axis. Firstly there is the animal study evidence that removal of the hippocampal negative feedback by ablation increases ACTH release; The glucocorticoid and mineralocorticoid receptors are expressed strongly in the hippocampus; High levels of corticosteroids lead to hippocampal shrinkage and impairment of declarative memory. Stress hormones can also reduce neurogenesis in the subgranular zone. This proposed relationship is still a bit controversial though, generally with opposition from the memory research community, and support from the neuroendocrinology community. There is an excellent review arguing against hippocampal HPA involvement in Behavioural Brain Research 127 (2001) 137-158 by Lupien and Lepage. Povmcdov 12:01, 16 October 2007 (UTC)

Move Anatomy further down?
Excellent article. I would only suggest that you move the (excellent) Anatomy section further down. While it's interesting to me, and while I would refer to it myself if I were reading a journal article and wanted more details, it's fairly technical, and you'd have to be pretty familiar with brain circuitry to get through it or understand why it was important. OTOH, the sections on role in memory and history are immediately understandable to a non-specialist reader. Nbauman 01:44, 21 January 2007 (UTC)


 * That seems quite reasonable. I'll go ahead and do that. Thanks for the suggestion! digfarenough (talk) 18:31, 21 January 2007 (UTC)

Memory
The start of this article explains what types of memory a lesion to the hippocampus will affect (declaritive, episodic, etc.) and what it will not affect (procedural, etc.). A much simpler catagorization would be -Lesions prevent formation of explicit memory and -Lesions do not prevent formation of implicit memory these two catagories were founded on lesional studies of the hippocampal area (and anterograde memory loss of a disorder caused by long-term alchoholism (which i forget the name of) primarily and should surely be included in the article. I thought about doing it myself, but i wanted to run this by other editors and i also find the wording difficult to edit. thuglasT 04:51, 27 February 2007 (UTC)

Sadly, those two articles are in a sorry state. I still think explicit and implicit should be included as the main catagorization however. thuglasT 04:56, 27 February 2007 (UTC)


 * To be technical, there are some forms of implicit memory that hippocampal lesions impair, trace conditioning, for instance (though I think Larry Squire argues that that only occurs when the subjects are aware of the contingency). There's also evidence of other roles of the hippocampus in implicit memory, and evidence for implicit learning of contexts . As far as I know, the jury is still out on that claim, though you could look at Larry Squire's work, as he does a lot on the link between the hippocampus and explicit/implicit memory. digfarenough (talk) 18:19, 27 February 2007 (UTC)

I have read a lot on the hippocamous and e/i memory. If by trace conditioning you mean mirror tracing tasks - all patients i have heard of with destroyed hippocampi are able to do this. I also know people are able to recoginise songs and be conditioned through puffs of air to the eye and many other classical conditioning teststhuglasT 01:39, 28 February 2007 (UTC)


 * By trace conditioning, I meant something like this: . Probably one of the better reasons for using episodic memory instead of explicit memory is that explicit memory refers to both semantic and episodic memory (and also: what is explicit memory in animals? I suppose it depends on your definition... granted, Tulving seems to still believe that only humans have episodic memory, though the recent paper from Clayton's lab might be the final nail in that coffin). I recall there being some evidence that HM has slowly formed new declarative memories, suggesting either a lack of a hippocampus greatly slows down creation of new declarative memories or that he still has a small amount of function hippocampus remaining. That's sort of an aside, though. But I think the fact that the hippocampus is needed for contextual fear conditioning shows that its role isn't purely in explicit memory (though, again, I could be wrong: maybe contextual conditioning would only occur in humans if they are aware of the contextual contingency). digfarenough (talk) 20:58, 28 February 2007 (UTC)

Are you certain that HM had absolutely no hippocampus? I somewhat recall there being a very small proportion left - perhaps this would explain HM forming new declarative memories. Also, ive breifly read ethology articles maintaining animals do have episodic memory. I personally believe that people dont believe it exists because its hard to prove. Reminds me of strict behaviourism. thuglasT


 * Yeah, I'm sure animals do (well, fairly sure). If they don't, the paper I'm about to submit might be met with skepticism... There was also a paper by, I think, Fortin, Agster, and Eichebaum in 2004 or so doing ROC analysis on rats that showed differential contributions of recollection and familiarity, suggesting at least an episodic-like process. But the Clayton paper is what provides really good evidence, I think. That might be true about HM, I forget, and I'd have to upstairs to ask someone who'd know, which I'm too lazy to do at the moment. :) digfarenough (talk) 21:22, 28 February 2007 (UTC)

Location - misleading
The hippocampus is not part of the the temporal lobe; to my knowledge, it is located structually within(under-ish) but still seperate in classification from the temporal lobe which is a part of the cortex which the hippocampus is NOT (it is part of the limbic system). Best way i can explain this is that the hippocampus is jelly in a doughnuts crust but it is not part of the crust.thuglasT 05:04, 27 February 2007 (UTC)


 * I dunno, I think it's fair to say it's part of the temporal lobe. In both rats and humans, it's right next to entorhinal cortex and subiculum (see the last figure in the article, for instance). But the hippocampus is indeed cortex, it just isn't neocortex. digfarenough (talk) 18:10, 27 February 2007 (UTC)

I was wrong - it is part of the cortex, but it is NOT part of the temporal lobe. It is under it. the temporal lobe is a lobe, the hippocampus is part of the limbic system which is not a lobe. The hippocampus evolved far before the temporal cortex was there as the temporal lobe deals with extremely complex functions (face perception in the infrotemporal cortex) and the limbic system (while equally amazing) deals with less evolved functions such as learning that we are less aware of such as learning emotion and motivation. thuglasT 01:36, 28 February 2007 (UTC)


 * (Computer crashed in mid-reply!) Basically I was saying: limbic system is not really a thing, it's a grouping someone came up with. Notice that orbitofrontal cortex is considered part of the limbic system, which is clearly neocortex and part of the frontal lobes. Also, the temporal lobe contains primary auditory cortex and, e.g., birds have both an analog of primary auditory cortex as well as one of hippocampus, so the two may have grown up together, in a sense. Certainly the Clayton paper I've mentioned shows that birds seem to have episodic memory. If you do change the wording, you shouldn't say "under" but rather something like "medial to". In humans the hippocampus is indeed ventral and medial to other temporal cortices, but in rats it's just medial, not really ventral (since in rats the hippocampus is rotated a bit and flipped upside down, as I recall, compared to humans). digfarenough (talk) 21:26, 28 February 2007 (UTC)

You said the limbic system isnt really a thing... to me if many papers/textbooks maintain is a grouping i would think it is a 'thing' is as if the system was not very closely related in function, structure, or evolutionary time line it probably would not be grouped together.

I was thinking under anyway, but i was trying to think of a better word. Maybe what we could compromis at is located structurally inside (or below/under) the temporal lob. I just don't like the idea of people thinking it 'located inside' means it is a region in the temporal lobe. This sounds good to me - what about you I apologize if it sounds like i am arguing - i just like to think about brains. :) thuglasT 21:48, 28 February 2007 (UTC)


 * You might be interested in this paper by Murray and Wise, arguing whether it is useful at all to talk about the "medial temporal lobe." I mention it because that paper along with Swanson and Petrovich (1998) argue that the amygdala isn't even a single thing, but rather just a term for a collection of anatomically nearby structures. That's just to say that traditional groupings of things sometimes have to change in light of newer data. Personally I still hear lots of people refer to the hippocampus as being part of the medial temporal lobe, so I have no problem with claims like that. Even the Murray and Wise paper isn't saying that the HC isn't part of the medial temporal lobe, they're just arguing that the MTL isn't a system with a single function, but rather a collection of functionally distinct components, which I also agree with. digfarenough (talk) 22:06, 28 February 2007 (UTC)

ill read that as soon as i get home - is adding structurally good for you? its good for me. this to me suggests it is not the same as the temporal lobe... thuglasT 23:04, 28 February 2007 (UTC)


 * Yeah, that sounds fine with me. digfarenough (talk) 23:45, 28 February 2007 (UTC)


 * Hm, the new wording sounds odd to me. "Structurally inside" is awkward and to me doesn't carry any different meaning than "in". I don't see any problem with considering the HC as part of the temporal lobe, as I've never heard the temporal lobe described as an exclusively neocortical structure. --David Iberri (talk) 00:38, 1 March 2007 (UTC)


 * I agree its a bit awkward i couldnt find a better wording. I guess the way i want to say it is the heart is located structurally 'in' the skin, but not categorically. Whatever - if more than one person doesnt agree - revert it. thuglasT 16:35, 1 March 2007 (UTC)

I tried to make it better. Dig im going to leave this one up to your approval. thuglasT 23:00, 1 March 2007 (UTC)

The first sentence of this article is incorrect (as is the above commentary). The hippocampus is part of the medial temporal lobe: http://scholar.google.com/scholar?as_q=medial+temporal+lobe. "Under the temporal lobe" implies that it is inferior to the temporal lobe, which you can see in the figures in the article (http://upload.wikimedia.org/wikipedia/commons/thumb/c/c9/Hippocampus-mri.jpg/200px-Hippocampus-mri.jpg) is not the case. Brockston 23:13, 19 June 2007 (UTC)

Place Cells
I'm having some problems with place cells. In all the (dozens of) papers I've read, they refer to place cells as cells tuned to parts of the environment, but I have some simple questions, which if someone can address, might help clear up this article
 * 1) when place cells (PCs) are activated by different parts of the environment is that because PCs have two different place fields (PFs) or is that because the PC has such a large PF that different parts of the environment can activate it
 * 2) what happens to spatial view cells (or PCs) when the primate (or rodent) is put in a new room? take a PC, does its PF change/move to become attuned to a different location in the environment?
 * 3) Essentially, what happens when a rodent does a 180? Are all the previous PCs overwritten? are the previous PFs hardwired now? do those PCs die? Paskari 14:26, 5 July 2007 (UTC)

Also I read Best 2001 and he/she states that in the O'Keefe and Dostrovsky (1971) experiment which coined the term place cell showed that only 10% of the cells were PCs. Does this still hold? what implications does this have on the cognitive map theory? thanx Paskari 14:55, 5 July 2007 (UTC)


 * Let's see... usually it's said that a place cell has multiple place fields if it fires in two distinct parts of the environment. This is supported by the observation (can't recall the reference offhand), that place cells will separately show theta phase precession in each field. Yes, in a new environment or room place cells will randomly remap (I think Muller and Kubie 1987 shows that, for instance). A couple studies looked at slowly morphing one environment to another and found somewhat differing results depending on exactly how the morphing is done: sometimes the cells will hit a threshold where all of a sudden remapping will occur, sometimes cells slowly shift around to keep a constant relation to things like the walls of the environment (Wills, Lever, Caccuci, Burgess, and O'Keefe 2005 for the latter, I forget the paper with the former, but I think it was pretty recent). When the rodent does a 180? In an environment where the animal has freely explored in multiple directions, place cells are not head direction dependent and so they'll just keep firing. On a linear track, studies have shown that different place cells fire for the two directions except at the animal's usual turn-around points (e.g. Gothard, Skaggs, McNaughton 1996, but other papers, too). It's true that not every cell will have a place field in every environment (which is at least partially due to the fact that that'd be awfully wasteful: you really don't need every single cell firing in every environment). I don't think a lot of people still believe in the original idea that the hippocampus is a cognitive map. It's certainly true that a lot of hippocampal cells have non-spatial firing correlations (Howard Eichenbaum has a lot of papers showing this in various ways). Hope that helps. digfarenough (talk) 13:59, 7 July 2007 (UTC)


 * Thanx, I just find it weird that there's so much data on place cells, yet I haven't been able to find a paper that easily and accurately sums up what a place cell is. I'm doing more review. Hopefully I'll be able to incorporate some of it into this page Paskari 17:48, 9 July 2007 (UTC)


 * Yeah, I can't think of a good review paper offhand. You could look at Skaggs et al. (1996) in the journal Hippocampus which focuses on phase precession of place cells but also has good information on place cells in general. There was recently a big book published on the hippocampus that you might find in a library that I'm sure has a place cell chapter. You should definitely look at context-dependent firing of place cells (for example Wood, Dudchenko, Robitsek, Eichenbaum 2000, Lenck-Santini, Save, Poucet 2001, Bower, Euston McNaghton 2005, Ainge, van der Meer, Langston, Wood 2007 Good authors to look at include Eichenbaum, Bruce McNaughton, Burgess, O'Keefe, and the Mosers (Edvard and May-Britt). Also grid cells are closely related to place cells. And if I may self-promote, we recently found a pretty weird effect on place cells during continuous spatial alternation (Lee, Griffin, Zilli, Eichenbaum, Hasselmo 2006) that also showed up in the data from Griffin, Eichenbaum, Hasselmo (2007), though I'm not sure how much it was emphasized in that paper. The list could go on and on... place cells can be interesting little guys, though I myself don't think they're directly involved in spatial navigation, despite their name. digfarenough (talk) 03:11, 10 July 2007 (UTC)

Hilar mossy cell
Mossy cells of the hilus are mentioned in the article. It would be great to have a separate article about them, if they deserve it. I've read that the loss of this type of cells is somehow implicated in temporal lobe epilepsy. --CopperKettle 12:08, 9 September 2006 (UTC)

Physiology EEG
At various places the article makes statements about Hippocampis' contibution to EEG, e.g., "generates some of the largest EEG signals of any brain structure. These reflect subthreshold membrane potentials and strongly modulate the spiking of hippocampal neurons and synchronise across the hippocampus in a travelling wave pattern".

First, the cited article and I suspect almost all articles that talk about Hippocampus oscillations do not use EEG but invasive recordings like LFP, MUA or similar. Second, the contribution of Hippocampus to EEG is not clear. EEG is dominated by cortical pyramidal cells. 93.219.42.111 (talk) 09:41, 4 March 2015 (UTC)

Computational models
Why no section on these -- there is a pretty huge industry in comp neurosci building them? Section could include functional HMM and Boltzmann-like networks as well as NEURON sims etc. Any suggestions? — Preceding unsigned comment added by 143.167.9.247 (talk) 15:10, 5 November 2014 (UTC)

Rearranging
I've moved much of the content of the anatomy section, and all of the content of the "hippocampal subfields" page, into a new "hippocampus anatomy" section, leaving behind the things I thought a non-specialist reader would most like to know. Reason: because more anatomy is needed, and this page would have become too large and awkward. Looie496 (talk) 16:55, 21 April 2008 (UTC)

Plans
This is a pretty sketchy article given the importance of the topic. I'm going to do some editing over the next few days to try to get into a bit better shape. I'm also going to archive the stale discussion here, in order to clear the ground a bit. Looie496 (talk) 03:51, 16 April 2008 (UTC)

Hippocampus and Sexual Dimorphism
I've previously read that the hippocampus is the most sexually dimorphic brain region, being significantly larger in men than in women. In fact, I'm sure I read this on wikipedia a while ago. Did there not use to be an entire "sexual dimorphism in the brain" page (not sure on the actual title)? I know this topic is controversial, and some findings have been refuted or challenged, but sexual dimorphism in the brain seems to have almost completely disappeared from wikipedia. I thought the difference between male and female hippocampi was fairly well established, but there's no mention of it here at all? —Preceding unsigned comment added by 79.65.165.192 (talk) 16:23, 18 February 2008 (UTC)

Not familiar with this. Can you give an authoritative reference? Looie496 (talk) 03:51, 16 April 2008 (UTC)

I am familiar with some of the physiology figures used and am almost positive that they were generated by Dr. Bill Skaggs. Would the user who posted them please make sure that they are attributed correctly. —Preceding unsigned comment added by ThetaMonkey (talk • contribs) 20:42, 23 July 2008 (UTC)
 * The user who posted them is, in fact, Dr. Bill Skaggs, and is pretty sure they are attributed correctly.Looie496 (talk) 22:07, 23 July 2008 (UTC)
 * Let me add that these are not necessary the best figures in the universe for the purpose, but at least I didn't have to worry about ownership.Looie496 (talk) 22:10, 23 July 2008 (UTC)

The topic of sexual dimorphism refers to the HYPOTHALAMUS not the Hippocampus --rb

Weasel Term
There's a weasel term in the Role in spatial memory and navigation section
 * Without a fully functional hippocampus, humans may not successfully remember where they have been and how to get where they are going. Researchers believe that the hippocampus plays a particularly important role in finding shortcuts and new routes between familiar places. Some people exhibit more skill at this sort of navigation than do others, and brain imaging shows that these individuals have more active hippocampi when navigating.

If no reference can be provided, it should be removed. Is the reference is at the bottom of the page, then there should be a link to it. Paskari (talk) 18:20, 3 August 2008 (UTC)
 * Before removing the text, you should check if the reference provided about the taxi drivers also is a reference for the text that you quote above (I don't feel like doing this). If not, please put a tag that a reference is needed. Then, if nobody puts in a reference for a reasonable amount of time (I would say at least a month), i guess it's okay to remove it if you wish. Lova Falk (talk) 18:32, 3 August 2008 (UTC)
 * I didn't write that material, but I agree with Lova that it was intended to introduce the paragraph that follows. The Maguire paper does support all the assertions here. If you feel like you can make the connection clearer, feel free to have a shot at rewriting it.  Simply repeating the Maguire ref for each sentence seems a little weird, but maybe that's what needs to be done. Looie496 (talk) 18:43, 3 August 2008 (UTC)
 * I'm just going to go ahead and put a tag requesting a reference. Paskari (talk) 20:40, 3 August 2008 (UTC)
 * Okay, I've fixed it, I think. Sigh. Looie496 (talk) 23:50, 3 August 2008 (UTC)
 * Good job, thank you! Lova Falk (talk) 08:28, 4 August 2008 (UTC)
 * Thanks for making the article more complete. Paskari (talk) 10:53, 4 August 2008 (UTC)

Thank you — Preceding unsigned comment added by 174.51.145.197 (talk) 05:39, 3 March 2014 (UTC)

H.M.'s Identity
Now that H.M. has been identified as of his death, perhaps a new article needs to be made on him, and H.M. text turned into links to that article? Or at least his name should be mentioned. I've included his name in the first mentioning of H.M., but I'm very new at this and don't know how to reference his NYT obit. It's http://www.nytimes.com/2008/12/05/us/05hm.html if anyone could take care of this. Pdmckinley (talk) 12:19, 6 December 2008 (UTC)
 * Very interesting! I put in the reference, which is a very easy thing to do. If you click on "edit" you can see exactly how it is done. However, I shortened your text, because information on his death and that his identity was revealed is not really relevant for an article on the hippocampus. Personally I don't think the article on H.M. should be renamed, because "H.M." shows up in every single textbook on neuropsychology. Lova Falk (talk) 12:37, 6 December 2008 (UTC)
 * Hah, nice to finally know that -- I knew he was "Henry", but never knew the last name. Looie496 (talk) 17:41, 6 December 2008 (UTC)

CA1
The CA1 region is mentioned in several images but not actually defined in the article. L&there4;V 23:06, 5 April 2009 (UTC)
 * Ah, seems as though that part was all moved to the separate anatomy page. I added in a short mention of subregions CA1 through CA4 in the anatomy section to address this comment. digfarenough (talk) 18:50, 8 April 2009 (UTC)
 * I'm intending a rewrite of the whole anatomy section in the near future, but in the meantime have made a couple of minor changes to fix problems. Looie496 (talk) 20:07, 8 April 2009 (UTC)
 * Thanks for adding the Moser and Moser reference. I'm not sure I completely buy the idea, but they do present some evidence that I hadn't seen before (especially Fig 1c, though I wonder if the CA3 axons have the same discontinuity...). I think I'd still feel better if the article's claim read "...both of which share similar composition but may be parts of different neural circuits." But it is quite possible that my objection is just a matter of semantics on what it means to be parts of different neural circuits. digfarenough (talk) 22:28, 8 April 2009 (UTC)

Fact tags
Jean-Francois Gariepy just added three "fact" tags to the article, two to the lead, one to the "Aging" section. This article is trying to follow the principle of not using references in the lead, so I am going to remove the two there. I will however add a source relating to Alzheimer's disease to the Aging section, which doesn't have a sufficiently strong one right now. The other fact tag in the lead relates to material repeated in the "Role in spatial memory and navigation" section and sourced there to the Moser 2008 review. As for the third fact tag (in the Aging section), the source is the same as for the previous sentence. I always have difficulties with this sort of thing -- repeating the same cite for sentence after sentence looks horrible to me, but I'll do it in this case. Looie496 (talk) 17:08, 3 June 2009 (UTC)


 * Just wanted to make sure that these facts were actual... I'm not a specialist of memory so I was not able to evaluate whether this statement was true : 'In Alzheimer's disease the hippocampus is one of the first regions of the brain to suffer damage; memory problems and disorientation appear among the first symptoms.' This is something I often heard but I had never seen any article stating this. Thanks for pointing out the Moser 2008 review, I probably won't read it since I'm pretty busy but I'll take your word that it is stated in this review. Jean-Francois Gariepy (talk) 13:41, 7 June 2009 (UTC)

Neurogenesis
There's not much discussion about neurogenesis in this article. Action potential discuss contribs 04:00, 19 June 2009 (UTC)
 * Yeah -- there's a bit, but I accept that there could be more. I wonder if adding a neurogenesis subsection to the Anatomy section would constitute appropriate weighting?  It's definitely a topic that interests a lot of people. Looie496 (talk) 04:11, 19 June 2009 (UTC)
 * Well. I think it would be interesting to include how new cell growth was measured in hippocampus with BrdU (Eriksson et al., 1998). Also talk about hippocampus studies in humans (london taxi driver study Maquire et al. (2001). There also some studies in the water maze paradigm with rats raised in improverished v. enhanced living environments. The rats in the enhanced living environments showed more new cell growth which lasted longer (Gould et al. 1999). Just a warning, this is based on my lecture notes -- I'm not an expert in this area. Action potential discuss contribs 05:39, 19 June 2009 (UTC)

Neurogenesis is specific to the Dentate gyrus rather than the entire hippocampus, and there is more detail in that article 194.83.141.34 (talk) 13:39, 17 September 2010 (UTC)

In mammals neurogenesis is ubiquitous in the subgranular zone (SGZ) in the hippocampus and the subventricular zones (SVZ) in the lateral ventricles. Still is a very very important topic in neuroscience research and has to be covered under hippocampus physiology. Gabriel arisi (talk) 07:29, 11 November 2010 (UTC)


 * Or perhaps the Anatomy section. If you're up on this topic and would like to add a summary of current knowledge, I would be completely in favor of that. Looie496 (talk) 16:52, 11 November 2010 (UTC)

Relating Hippocampus to Hippopotamus
Hippocampus derives from the same word as the animal Hippopotamus does. This link is used for memory connection; for as the hippocaumpus is the portion of the human brain for relating memory the Hippopotamus is one animal that is heavily known for its memory cognition too. Hippopotamuses can retain long-term memory and have a instinctive nature for protecting their babies as well as other herd and other mammals offspring as well. —Preceding unsigned comment added by Pttp55 (talk • contribs) 16:13, 5 November 2009 (UTC)
 * I'm not sure whether you are serious, but the connection is the root "hippo", horse. --Crusio (talk) 16:19, 5 November 2009 (UTC)

Seahorse picture
This photo of Laszlo Seress's preparation of a human hippocampus, alongside his pic of a seahorse, has been reproduced in Andersen's "The Hippocampus Book", page 10, and Rudy's "The neurobiology of learning and memory", page 237. Professor Seress has nothing against these appearing on the internet. Before I go to the trouble of arranging the license (I've never done it before), can I please have a show of hands for and against inserting it into this article? Anthony (talk) 12:41, 21 January 2010 (UTC)
 * I would be 100% in favor of that -- it's a great picture. Looie496 (talk) 18:33, 21 January 2010 (UTC)
 * Let me add that I don't see any need to wait for more opinions -- as long as the picture is properly licensed, I can't imagine that anybody would object to it. Regards, Looie496 (talk) 22:06, 21 January 2010 (UTC)

Professor Seress has agreed to the image going public domain. I'll post it soon. His last email said:


 * ...very few people understand that this is among the relatively few anatomical names in the brain where we don't know the reason why the name was given. In most cases the descriptions also include the reason. In this case not, and even the great Hungarian anatomist professor Janos Szentagothai wrote in his anatomical textbook that two names appeared for this structure  in the 1500-1600 something years, hippocampus and silk worm and probably silk worm would have been better to kepp, because the structure sesembles silk worm, but not hippocampus. Actually, a german professor (Tübingen), JG Duvernoi in 1735 already raised this question, mentioning the structure as silk-worm. The name was given by JC Arantius in his book in 1587 (Venice). More detailes see W Seifert book Neurobiology of the Hippocampus, 1983, last part, Epilogue.

If I can edit this and an earlier email into something not too WP:OR, would a paragraph on the origin of the name be appropriate here? Anthony (talk) 10:10, 1 February 2010 (UTC)
 * Well, Laszlo gave you the references, so it would not really be OR, I think. --Crusio (talk) 10:57, 1 February 2010 (UTC)

This is a nice picture, but I would like to question whether it accurately illustrates the origin of the name. First, the preparation looks like it includes the entire fornix in addition to the hippocampus; the hippocampus alone does not look much like a sea horse. Second, I always thought that the name derived from the shape of the cross-section, not the shape of the three-dimensional structure. The etymology in The American Heritage Dictionary reflects this view:


 * hip·po·cam·pus
 * NOUN:
 * pl. hip·po·cam·pi
 * A ridge in the floor of each lateral ventricle of the brain that consists mainly of gray matter and has a central role in memory processes.
 * ETYMOLOGY:
 * Late Latin, a sea horse with a horse's forelegs and a dolphin's tail (from its shape in cross section)
 * ETYMOLOGY:
 * Late Latin, a sea horse with a horse's forelegs and a dolphin's tail (from its shape in cross section)

Nasorenga (talk) 18:42, 5 August 2010 (UTC)


 * Interesting. I guess somebody would have to read Aranzi's description to figure out for sure which aspect he was talking about. Looie496 (talk) 01:58, 6 August 2010 (UTC)
 * I was looking at a pic of a hippocampus cross-section the other day and thought "That looks like a seahorse!" Anthony (talk) 17:59, 1 October 2010 (UTC)
 * From By Euan M. Macphail. p. 187"It is, however, not entirely clear why he used the term (for an entertaining and fascinating account of this topic, see Lewis, 1923). According to Lewis, 'The flight of fancy which led Arantius, in 1587, to introduce the term hippocampus is recorded in what is perhaps the worst anatomical description extant. It has left its readers in doubt whether the elevations of cerebral substance were being compared with fish or beast, and no one could be sure which end was the head.'"From  By Henri M. Duvernoy. p. 1"'Hippocampus, silkworm, and ram's horn were thus the terms used at the end of this initial period, all based on the intraventricular appearance of the hippocampus.'"Both cite Lewis FT (1923) "The significance of the term hippocampus." The journal of comparative neurology 35 213–230. So the likeness of the structure to a seahorse was not impressive but, assuming Duvernoy read Lewis correctly and Lewis read Arantius correctly, I prefer the surface shape over the cross-section explanation - at least until we know the provenance of the AHD etymology. Can anybody access Lewis? Anthony (talk) 16:32, 2 October 2010 (UTC)
 * Lewis' paper is available online,, with the relevant section from Arantius reproduced on page 217. It seems clear that it was the shape of the whole structure, not its cross section, that Arantius found similar to a seahorse. Nasorenga (talk) 18:47, 4 March 2015 (UTC)

Stress damage to the hippocampus
The notion that glucocorticoids damage the hippocampus in PTSD is very, very controversial. There is good evidence that smaller hippocampi is a predisposing factor for PTSD (as opposed to PTSD causing small hippocampus), and furthermore there is almost zero evidence that cortisol levels are increased in PTSD- if anything, cortisol is decreased in PTSD. A sentence or two about that would be good.

PubMed citations: 12379862 11345128 MBVECO (talk) 22:30, 2 April 2010 (UTC)


 * I wrote that because I thought the topic was too important to leave out, but I acknowledge that I don't have deep familiarity with the literature on that stuff. Please improve it if you see something that could be better.  Regards, Looie496 (talk) 19:47, 4 April 2010 (UTC)

HOW?
how the memorie`s are stored in hippocampus?what`s the physiology of the storage?Sina jose (talk) 08:13, 21 April 2010 (UTC)

Sharp waves
I was thinking the section on sharp waves should have a note on the Girardeau et al. 2009 study published in Nature Neuroscience. Surely taking the Buszaki model a step beyond correlation measures deserves a nod, mentioning that suppression of SPW-Rs impaired performance in a spatial memory task. This is a reasonable addition, no? (Although I'm not too experienced with how wiki formats references, so I've not made any changes myself...) —Preceding unsigned comment added by Neurokeen (talk • contribs) 19:31, 27 April 2010
 * It's a pretty cool paper and I wouldn't object to a mention. The easiest way to set up a citation is to use this tool, which only requires you to know the Pubmed id.  I'll keep an eye on the article and check your syntax if you add anything.  Regards, and welcome to Wikipedia. Looie496 (talk) 16:18, 1 October 2010 (UTC)

The Great Hippocampus Question and the hippopotamus
Having some info to hand on the above issues, I've edited the naming section to give more info from the previously cited reference, and expand it a bit using an additional reference. IJsbrand van Diemerbroeck needs an article, IJsbrand van Diemerbroeck covers him as does Britannica. . dave souza, talk 12:27, 3 October 2010 (UTC)
 * Hi Dave. Recently, I changed "the three main histological divisions of the hippocampus: CA1, CA2 and CA3" to "the four main histological divisions of the hippocampus: CA1, CA2, CA3 and CA4." You have changed it back to 3. Was that deliberate or an oversight? Anthony (talk) 08:04, 4 October 2010 (UTC).
 * Oops, my error, saw your change but didn't notice that I was working from an older version. Have changed it back, no idea which is right. . . dave souza, talk 09:17, 4 October 2010 (UTC)
 * Thanks. I'm not sure either, but I see more references to 4 than 3. Anthony (talk) 11:53, 4 October 2010 (UTC)
 * CA4 is sort of a controversial area -- some anatomists consider it to be the same thing as the hilus of the dentate gyrus, others a distinct part of the CA layer. My memory isn't good enough to say exactly who say what. Looie496 (talk) 18:13, 4 October 2010 (UTC)
 * Oh. Slowly, things are becoming less muddy. Anthony (talk) 18:31, 4 October 2010 (UTC)
 * CA4 is indeed often not counted as part of the hippocampus proper any more, but part of the gyrus dentatus. In mice (nowadays a popular study species), it is difficult bordering on the impossible to distinguish CA2 from CA1/CA3. I have never seen an article that properly defined CA2 in mice, even though numerous articles claim to have studied characteristics of CA2 in mice. unfortunately, I have no time right now to dig out the sources... --Crusio (talk) 18:34, 4 February 2011 (UTC)

Removing new "Depression" section
A new "Depression" section was added yesterday saying ''There have been studies suggesting that depression has a "toxic effect" on the hippocampus, and may cause permanent damage thereto. ''. I am removing this for the moment because material in a featured article ought to use WP:MEDRS-level sources, which this is not, and because the effect of depression on the hippocampus is already mentioned in the section on stress. The source being used here does not even directly connect the effects to the hippocampus. I don't necessarily object to saying more about depression if there are good secondary sources available that it can be based on, and if the information relates directly to the hippocampus. Looie496 (talk) 18:20, 4 February 2011 (UTC)

Regarding the behavioral inhibition theory
We just had an edit by Turf Einar removing a couple of lines from the lead, which was reverted by Crusio. Although it was me who wrote those lines, I am tempted to agree with Turf Einar here -- the ideas are historically important but aren't currently given much attention, so perhaps they don't belong in the lead. The material is still present in the Functions section, it it wouldn't be lost from the article if the mention in the lead was dropped. Any responses? Looie496 (talk) 16:37, 24 August 2011 (UTC)
 * No problem with that, I just thought that removing all this stuff from a featured article without further discussion was doing things a bit too rapidly. As long as the hyperactivity in lesioned animals and the inhibition theory itself are covered in the article, I don't object to removing it from the lead. --Crusio (talk) 16:44, 24 August 2011 (UTC)

First sentence - hippocampus as feature of vertebrate brain
Hi. I have no time to contribute to editing at the moment (busy teaching this material), but I have an issue with the very first sentence: "The hippocampus is a major component of the brains of humans and other vertebrates."

In fact, the presence of a brain region shaped like, organized like and functioning like the mammalian hippocampus is NOT a feature across all vertebrate groups. Birds are now considered to have an 'honorary' hippocampus, i.e. a region that differs anatomically, organizationally and with respect to location, yet has similar function. This is (so far) not the case for other vertebrate groups.

Until I (or someone else) has time to add a section, this is easily fixed by replacing vertebrates with "mammals" in the first sentence. — Preceding unsigned comment added by 129.97.24.137 (talk) 23:22, 17 January 2012 (UTC)


 * It's not clear to me why you call the bird hippocampus "honorary". I agree that it is quite different in structure from the mammalian hippocampus, but it is nevertheless clearly homologous, so there is pretty good justification for using the same name.  In any case the issue is discussed more thoroughly in the Evolution section.  I'm certainly open to changing this, but it seems to me that simply changing vertebrate to mammal would make it at least as misleading in the opposite direction.  Regards, and thanks for the comment, Looie496 (talk) 03:23, 18 January 2012 (UTC)

Pathology#Aging: “normal, healthy aging”
I have trouble with that phrase. I'm yet to observe a type of aging that's healthful. It's a cliche—a dangerously misleading cliche, what's worst. Everything Is Numbers (talk) 12:31, 8 August 2012 (UTC)
 * Reasonable point. I've removed the word "healthy", so now it is just "normal aging". Looie496 (talk) 16:08, 8 August 2012 (UTC)
 * Oh hey, Looie. I see you're all over Wikipedia.
 * Yes, that solves the problem, as I see it. I have my reasons for disliking “normal” too, but it's a much more minor concern, and I don't want to be a nudnik. I hoped that you would ask why I made such a big deal out of it. Why the said phrase is dangerous, to one degree or another, is because it contributes to the same mentality that keeps hindering progress in experimental biogerontology. It's allied with notions that senescence is inevitable, unharmful, necessary or—can you believe it?—desirable! Everything Is Numbers (talk) 15:57, 9 August 2012 (UTC)
 * That's a very interesting issue, but I think it falls outside the scope of this talk page. Regards, Looie496 (talk) 16:07, 9 August 2012 (UTC)
 * Hm, probably. Be well. Everything Is Numbers (talk) 20:33, 9 August 2012 (UTC)

Etymology
Greek scholarship is not what it used to be. Κάμπος is not Greek for sea monster but the masculine form of a noun meaning "coiled". Its feminine form Κάμπη was the name of a monster that guarded the Cyclopes, half woman and half scorpion, whence probably someone thought the word must mean a sea monster. The closest rendering of the two words in English would be something approximating a "coiled horse" - monstrous as that might be, it is not the same as "horse sea monster". I have, therefore, corrected the etymology. Skamnelis (talk) 06:05, 22 February 2013 (UTC)
 * Cool. Looie496 (talk) 06:25, 22 February 2013 (UTC)
 * As one of the many who never learned any Greek, I thank you for your edit!  Lova Falk     talk   06:59, 22 February 2013 (UTC)