Talk:Depolarization

Discussion

Memenen,

While I like the elegance of your changes and the shortening of my rather verbose prose, I have to disagree with your characterization of "original meaning" vs "literal meaning" of depolarization. The "depolarization is up, hyperpolarization is down" nomenclature is not just a subtle variation of the original meaning. Its just plain wrong. When I first tackled this article, I (being new to wikipedia) was just trying to be nice and to leave some of the original text. What I should have done was to completely re-write it in order to make the actual meaning clear. The useage that leads to the people saying the entire rising phase of the action potential is "depolarizing" is merely sloppy use of nomenclature propagated by teachers over simplifying things for their students. It seems to me, that in an encyclopedia, we should actually strive to get it right. I am guilty of this as well, by trying to explain an incorrect useage as vernacular (which it is). But I think it should be described correctly and then we can allow that it is commonly used another way. The incorrect useage is not the definition.

In biological membranes, changes in electrical potentials almost always stay on one side of zero (and almost always the negative side), so the terms hyperpolarization and depolarization as "down and up" are correct in these cases. It is in the special cases, such as the action potential where 0 volts is crossed that it becomes complicated. This is why it the action potential is usually said to have a "rising phase and falling phase" rather than a depolarizing and hyperpolarizing phase. It's simpler than saying "the action potential depolarizes and hyperpolarizes (rising phase) then depolarizes and hyperpolarizes (the falling phase). But in the special case of the action potential, the distinction is particularly important. It was the very fact that the action potential overshoots 0V (hyperpolarizaes above zero) that provided the impetus for Hodgkin and Huxley's work. The fact that the AP overshoots meant that at least two currents must be at work, rather than just one.

I write this because I don't want to get into a fight where we keep changing each other's descriptions back and forth, but in my view the way this article should be outlined is:

1. Depolarization is 'more' polarization of the membrane
2. aspects of depolarization
3. misuse and vernacular uses of the term

Anyway, perhaps we could discuss it here and reach a consensus.

Synaptidude 5 July 2005 22:56 (UTC)

Synaptidude- I'm glad you are willing to take on the task of fixing this.

I'm not sure what you mean by "Depolarization is 'more' polarization of the membrane".

• • When I say that "depolarization is more polarization" I say that in the sense that depolarization is "less" polarization ;-). IN other words,,,,brain fart Synaptidude 01:28, 13 January 2006 (UTC)

Hey! Maybe we should do an article on Brain Farts.Synaptidude 01:28, 13 January 2006 (UTC)

I could cite many examples (here is one that is online) of common usage of "depolarization" that is "technically wrong". I agree that this arises from the attempts of teachers and textbook writers to talk about neurophysiology to students who may learn all of their neurophysiology in just one or two short class periods. In my view, this "battle" was lost long ago, and "depolarization" has taken on a new meaning in the contexts where 99% of people first confront the term: in learning the basics of action potentials.

There are two differing views of language. In one view, languages are living social constructs and tools that people are free to use as they see fit by consensus of their social group. In another view, languages are what the writers of dictionaries and other "authorities" say they are. Such "authorities" typically dislike the idea that they can go to the trouble of figuring out what a word means, writing down what the word means, and then watch helplessly while people use the word in a different way.

I am not an advocate of letting people use words in any way they like. However, I think it is wise to be realistic about the way words take on new meanings in different social contexts. It is probably true that working electrophysiologists will always use "depolarization" in its original sense, but they would waste much effort trying to prevent the rest of the world from using "depolarization" in other ways.

The original author of the "depolarization" article (User:Diberri) probably is the perfect n=1 test case. He probably learned what most students learn about "depolarization" and passed it on. It would have been best to nip this whole thing in the bud (March 11, 2004 in hyperpolarization), and I have no complaint if the first paragraph (or all paragraphs) is changed to give the technically correct meaning of "depolarization".

I like the idea you suggested of giving a technically correct account first, then discussing the "wrong" way that "depolarization" is used. Here is some more discussion of why people go "wrong":

A common way for language to change is for people to shorten phrases is attempts to be economical with their sentences. I'm not sure if you have ever had the "pleasure" of trying to get through a lecture on the neurophysiology of action potentials (and I'm not talking about some graduate level course where you are training neurobiologists, I'm talking about typical biology students who have always avoided math). For introductory biology students, you can start describing the rising phase of the action potential by introducing the technically correct meaning of "depolarization" and "hyperpolarization" then saying something like "membrane potential change in the depolarizing direction from the resting potential". You have to explain how sodium currents cause the depolarizing membrane potential change from at the start of the action potential. In general, you will not have time, nor would it be constructive to pause and say, "Note that during the rising phase of the action potential the membrane potential change is first depolarizing, then it becomes hyperpolarizing. Similarly, during the falling phase, the membrane potential change is first depolarizing and then hyperpolarizing." I tell you from experience that it just is not productive to tell this to most introductory biology students. Usually a student in the class will notice this, and may ask a question about it, but it is not worth making a big deal out of it. There is not time and it will just confuse most of the students. Typically, the second time a student learns about action potentials (and here we can picture User:Diberri in some undergraduate physiology course) they are exposed to equilibrium potentials and you can describe the rising phase of the action potential in terms of membrane potential change towards the sodium equilibrium potential. The idea of an equilibrium potential is a conceptual leap that most people (who have weak math backgrounds) never make.

In my mind, it is not clear how to deal with a technical term such as "depolarization" in Wikipedia. People like User:Diberri can be taken to the "next level" by moving them past what they learned about "depolarization" in school, but most people who come along are going to be even that far along. In constructing understanding in people, sometimes you have to over-simplify at first. Once basic concepts are in hand, then you can make a second pass through the topic and become more technically correct and introduce more detail. Maybe it is an error to even mention "depolarization" in a section of the action potential page such as "Basic features". It would be possible to write a "beginners" account of the action potential without using the words "depolarization" and "hyperpolarization". Rather than introduce these concepts to a beginner, it is more important to introduce concepts such as ion channel gating by changes in membrane potential. It is really just a technical detail that action potentials start with a depolarization; for a beginner they just need to see that there is a change in the membrane potential and they need to relate that conceptually to the ion channel opening and closing. Maybe the "beginner's" account could be called a "qualitative" or "conceptual" account and totally avoid any numbers. Later in the action potential page there could be a quantitative description of the action potential. --68.228.251.234 6 July 2005 01:05 (UTC)<-- --Memenen 6 July 2005 01:07 (UTC)

I actually agree with what you said about 99% (the 1% being the "let it go" part ;-). Interestingly, part of my reason for "getting it right" comes from experiences with undergrads. When you teach them the shorthand of "the rising phase is (all) depolarizing", it actually makes it more difficult to make that seconds pass because they have internalized the concept that the rising phase is all depolarizing. It is true that it is only in more advanced classes that you even have a shot at teaching undergrads about equilibrium potentials, but if you do get the chance, then it's easier if you don't have to correct their bad concept first.

My feeling here is that there will not be a ton of people interested in reading about depolarization, except that they somehow are trying to understand it better, so why not give the actual definition? I understand what you are saying about the evolution of language. I agree that sometimes, no matter how frustrating, you just have to let it go. Otherwise, you become like the French ;-). The one place where I think one should not let it go is when it's hard science. Membrane polarization is basically physics. Physics is precise and to understand it, everyone has to know what the terms mean.

I agree that there is a gray area here because even scientists use the term incorrectly (hell, I do it), but I think in a forum where you are actually defining it, it should be defined correctly. However, we also cannot ignore that the literal and technically correct definition could cause confusion among readers who have learned the vernacular. That is why I think we need to include a discussion about the way the word is actually used in the world.

I agree with the AP there should be a qualitative description, followed by a more technical one. I'm not sure how quantitative that should be. I think the AP can be described technically correctly without using math. I also think that if someone is sophisticated enough to understand the kinetic models of APs, they can just read a review article, if not the original HH papers (yeah, right ;-).

So what I would like to do is to provide a technically correct definition of depolarization and then clue everyone into the way the world is actually used in the world. My view is that its OK to misuse it as long as you know you are misusing it (i.e. you don't misconceptualize it). I think that when teaching it, one should never misuse it.

Speaking of misuse, when I said that "depolarization is 'more' polarization, I meant "more" in the sense of "less" (i.e. I even confused myself and got it backwards). Synaptidude 6 July 2005 05:51 (UTC)

To Synaptidude: You wanted to "reach a consensus". I do not think n=2 can produce "consensus", so I suggest another end point. When you know what you are doing, BE BOLD. Just fix it.

To User:Diberri: I'm not sure if you are following this. I want to thank you for having started depolarization and hyperpolarization. I hope you are not offended by my use of you as an example (see above). --Memenen 6 July 2005 22:18 (UTC)

What would be really great would be to merge the depolarization and hyperpolarization articles into one membrane polarization article. But I don't know how to do that. Since there are only 3 of us who seem to care (you me and Diberri), that seems like pretty much a 100% consensus ;-) Synaptidude 6 July 2005 22:49 (UTC)

At first, I was going to ignore this discussion, which I originally saw as a pedantic splitting of hairs. But since my name's been brought into the mix, I feel obliged to comment. :-)

As one who originally learned the vernacular definitions, I was confused for some time about the naming of the terms hyper- and depolarization. After all, polarized makes me think "far from zero", so why did all my professors equate HP with "increase" and DP with "decrease" in membrane potential? Thus the vernacular usage has always baffled me.

Of course, just as Memenen says, instructors are probably just trying to simplify things for undergrads who will probably never again have to deal with action potentials. But I think that oversimplifying (e.g. by giving the incorrect (vernacular) definition more prominence than the correct one) has a great potential to do more harm than good. So I agree with Synaptitude that we should present the most correct definition, making a note that the term is universally misused by students and elecrophysiologists alike.

(After receiving an edit conflict) Memenen, no offense taken. Though I don't particularly like being labeled a clueless student (I have read HH's original paper [and will hopefully never encounter limit cycles again for the remainder of my life] ;-), I admit that my relevant edits to this pair of articles didn't help much. Cheers, David Iberri | Talk July 7, 2005 00:05 (UTC)

P.S. Please try indenting your posts with one or more leading colons to aid readers. Otherwise, this page looks like one big unruly mess. --David Iberri | Talk July 7, 2005 00:07 (UTC)

First, I'm no electrophysiologist, but given the context of this article i would think that the common usage should be first and then explain that technically the common usage is wrong. (At present you descrbe the technically correct definition and then mention that is not the comon usage.) Do electrophysiologists really still use the defintion of depolarising with respect to action potentials to mean approaching zero? I have found in biology that the definition of terms can often change their meaning. While this is frustrating for purists it is also a fact of life. Two examples are gene and epigenetic. I think these terms are used quite differently now compared to 50 years ago. As long as the defintions are defined with respect to common usage I do not think there is a problem. Just my two cents. I skip read the discussion above so i'm sorry if I missed the nuances. David D. 7 July 2005 00:46 (UTC)

Could you break the article into two sections? Approaching zero argument for one section and action potential usage in the other section. I think that format would be easier to understand since a reader can easily jump to the section with the most relevent usage for their needs. David D. 7 July 2005 00:50 (UTC)

Yes I'd be happy to do that. You did miss the part of the discussion where we made our cases for why the correct nomenclature. To answer your question about scientists and electrophysiologists useage of the term. First if you press them, most biologists will tell you they don't know squat about electrophysiology. They are exagerating, but it's been my experience that the typical non-electrophysiologist scientist has only a passing knowledge of electrophysiology (less that clueless student David, for example). Even among electrophysiologists (defined as people who do electrophysiological experiments), about half do not understand that the nomenclature is used incorrectly. There are a lot of dilitantes working in the field. About a third could explain the distinction between the technically correct and vernacular useage if you pressed them. They mostly just don't think about it and just use the shorthand out of lazyness, or for a more arcane reason it's not worth explaining. The remainder understand that the vernacular nomenclature is actually misleading. You understand the biology better when you understand the correct meaning of the nomenclature.

The solution is, I think, the one we have proposed. Give the correct meaning, explain the vernacular useage. In which order that is done, I don't really care. Synaptidude 7 July 2005 01:53 (UTC)

• exaggerating
• dilettantes
• laziness
• usage

no offence;) anyway, i think the best terms to use are rising, falling, and overshoot. My textbook (incorrectly, according to you guys) labels the "falling phase" repolarization, an article which you haven't seemed to have touched, even though you've done great work on this article and hyperpolarization203.218.234.235

Resting potential

Since the discussion of resting potential in membrane potential has problems, I am going to create an entry for resting potential on the resting potential page rather than let it redirect to the membrane potential page. - Memenen 7 July 2005 15:45 (UTC)

This debate on the word meaning is confusing the heck out of people, myself in particular. Please leave the majority of the debate to the discussion board or a seperate section of the article and put the Most Commmonly understould, used version of the word.

mike

Comments

I am an undergraduate psychology student at Nebraska Wesleyan University and will be working with my instructor Michele Petracca and the APS Wikipedia Initiative to improve this article this semester. While editing this article for the Neuroscience Project, I am looking to read and use these sources:

Brain Structure: Depolarization & Neurotransmitters. (2014). Retrieved March 6th, 2014 from http://schoolworkhelper.net/

Carlson, N. R. (2013). Physiology of Behavior. Upper Saddle River, NJ: Pearson Education Inc.

Doherty, M. (1991). Behavioral evidence of depolarization block of mesencephalic dopamine neurons by acute haloperidol in partially 6-hydroxydopamine-lesioned rats.

Behavioral Neuroscience, 134(4), 579-587. doi: 10.1037/0735-7044.105.4.579

Grover, L. M. (1987). Temporal order sensitivity of associative neural and behavioral changes in Hermissenda. Behavioral Neuroscience, 101(5), 658-675. doi: 10.1037/0735-7044.101.5.658

Walter, J. [Walter Jahn]. (2012, November 2). Ap1: Neuron action potential: depolarization along axon. [Video file]. Retrieved from http://www.youtube.com/watch?v=ooI7xT59hE8 — Preceding unsigned comment added by Katelyn0902 (talk • contribs) 05:47, 6 March 2014 (UTC)

Any suggestions or input along the way would be greatly appreciated. Katelyn0902 (talk) 15:12, 6 March 2014 (UTC)

While some of the sources are good, others are a bit more dubious. Those I would advice against using are the first and last.

For an overview of what are good sources for these types of articles see WP:MEDRS, we primarily use secondary sources such as professional text-books, reviews and position statements from major international organizations. Therefor the first and last source disqualify. The 1991 source is both old and a primary source so I would advise if you do use it you should instead use a later review citing it (if possible).

Also remember depolarization also occurs in the heart, and even if you do not mention in your expansion the article should have at least a header with Heart and a sentence there as well.

Check out WP:MEDMOS for a guideline as to how these articles can/should be structured.

Check out these images if you want any to add (all are free):

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--CFCF (talk · contribs · email) 21:44, 6 March 2014 (UTC)

Thank you for your comments. The pictures were very useful and I have added a brief section regarding depolarization in the heart. I am considering possibly adding one more picture. Katelyn0902 (talk) 14:05, 17 April 2014 (UTC)

Peer Review

All of the grammar and organization looks really good for your article. I like how you start with a more broad view of depolarization and then narrow in on some key aspects. However, I would maybe consider expanding upon depolarization blockers and depolarization in the heart. You could talk about depolarization in other parts of the body and how that helps the body function or how it is harmful. You could also talk about diseases associated with depolarization, if there are any. If you wanted, you could also talk more about what action potentials are and what they do. Shelbyknorr23 (talk) 02:50, 23 April 2014 (UTC)

Can depolarization occur with other ions besides K+, Na+ and Cl-? If yes, you could possibly incorporate other examples or briefly mention that it can be seen using other types of ions. You could also go into more depth with an explanation of the picture, discussing why such a decrease below the resting potential is seen at step #5. In your “Depolarization of the Heart” section, an explanation of the acronyms SA and QRS can be furthered as well. Overall, everything looks well-organized, especially considering the level of difficulty when writing an article like this! Cbruha11 (talk) 16:11, 23 April 2014 (UTC)

Thank you both for your helpful input. I have made changes accordingly. I did not have the resource used for the depolarization blockers and my textbooks did not go into much detail about them, so further research would need to be done to elaborate on that topic. I did not focus so much on the idea of action potentials, but rather on depolarization because there is a separate page that explains what they are. When considering the ions, the sodium potassium pump is the main component of membrane potentials that maintains the concentration gradients for both sodium and potassium. I have expanded the section on depolarization in the heart to an extent, but tried more so to focus on depolarization in neurons of the brain for the purposes of our class Katelyn0902 (talk) 23:33, 30 April 2014 (UTC)

New class project

I am an undergraduate biology student at Clemson University, and I will be working on improving this page for a class project under the supervision of Dr. Lesly Temesvari (Username: LTEMESV). I will be reorganizing some of the existing information on the page as well as adding information from the following two sources to further expand upon the information already contained on this page as well as to increase the accessibility of the page to those without a background in cellular biology.

Lodish, H., Berk, A., Kaiser, C., Krieger, M., Bretscher, A., Ploegh, H., & Amon, A. (2000). Nerve Cells. In Molecular Cell Biology (7th ed., pp. 695, 1021-1022, 1025, 1045). New York, NY: W. H. Freeman and Company.

Callies, C., Fels, J., Liashkovich, I., Kliche, K., Jeggle, P., Kusche-Vihrog, K., & Oberleithner, H. (2011, June 1). Membrane potential depolarization decreases the stiffness of vascular endothelial cells. Retrieved December 1, 2014. Prodger1 (talk) 08:30, 3 December 2014 (UTC)

New edits

@EredLuin: Because the typical resting potential is negative, it is more accurate to say that depolarization starts from a negative potential, rather than from a slightly positive one. Also the channel blocking domain of typical voltage-gated ion channels is on the cytoplasmic side of the membrane, not the external side. --Tryptofish (talk) 00:49, 10 January 2018 (UTC)

@Tryptofish: I agree with what you just wrote in this comment, but what you initially wrote in the article was about charges, not about potential. You wrote that the charge went from negative to positive, which is a dangerous shortcut since the actual electrical charge always stays positive overall. This is why I wanted to correct it. Again, if you rephrase it the way you just did in your comment, I agree. I'm sorry about my mistake about the side of blocking domain, but I again do not agree with the direction in which the ions you drew were moving. The extracellular fluid is richer in Na+ and this Na+ is what causes depolarization by coming into the neuron. What was shown on the original figure were unspecified ions going out of the cell, which is conceptually wrong when talking about depolarization. The multiple changes in your article were a mishappening on my part, I had only planned one but there was an issue with my connection so I thought the changes had not been taken into account. I do not plan an edit war, if you are worried about that. But I think you should reevaluate your original text and figure.--EredLuin (talk) 09:56, 10 January 2018 (UTC) 9:52, January 10th 2018 (UTC)

Thank you for that thoughtful reply, and welcome to Wikipedia by the way. Just so you know, the original text isn't "mine" (nor anyone else's), but I was just the editor who was here at the time. And I figured that you weren't really planning to edit war, but I felt that I needed to get your attention. It's quite understandable that a new editor would be wondering why their edits were apparently not sticking.

Anyway, to the substance of the matter. You are absolutely right about the way that the ions are shown passing across the membrane in the image. I suspect that the image was created for K⁺ rather than Na⁺. I had missed that, and apparently other editors had too, so thanks for noticing it. But I guess that both versions of the image are wrong for our purposes here. I modified another file from Wikipedia Commons, and will replace it with that.

As for charge versus potential, I guess one can differentiate between net charge and absolute charge, but since the concept is almost always expressed in terms of voltage, and that is how it is displayed in the figure in the lead section, I think that it is clearer to a general audience if we write it in terms of voltage instead. If you feel strongly that we need to describe charge instead or in addition, let's discuss that.

I'll make an edit now to try to implement these things, and please feel free to correct any mistakes that I make. Thanks again for discussing these issues. --Tryptofish (talk) 19:41, 10 January 2018 (UTC)

@Tryptofish: I saw that the article was changed and I much prefer this version! It doesn't matter if you talk about actual charges or potential, but it has to be consistent and we have to make sure not to confuse the two. Just today, I had the same discussion again, because the person said "charges" but meant "potential" so I didn't understand why they were saying that the interior of the cell is negatively charged. They meant that it was less positively charged which results in negative potential. So now it is clearer in the text!

Also, I you want to be more precise, maybe you should say that what we call "depolarization" usually refers to the first sub-treshold phase before the action potential. In that sense, when the channels close and deactivate, it is not the end of the depolarization phase, but actually the end of the whole action potential. That way, your text fits with the classic triphasic view of the action potential and you don't feel like you completely neglected the role of K+ in the action potential. But this depends a little more on how you view the phases I guess. At least now, there are no actual mistakes in what you wrote, It is just a little oversimplified (for education purpose, I suppose). --EredLuin (talk) 15:48, 17 January 2018 (UTC) 15:48, 17th January 2018 (UTC)

Good, I'm glad that we were able to fix those things. About the sub-threshold depolarization, my experience has been that "depolarization" is also frequently applied to epsps (of course, those can also be the same thing). --Tryptofish (talk) 22:39, 17 January 2018 (UTC)