Talk:Chemical synapse

message: That's as maybe, but I want also to add that there are different kinds of synapse. Most are chemical in nature, such as are already described. However, there is evidence for some very fast acting synapses which are electrical. These are reported to have been discovered in fish. Assuming that this has not been discredited, it would be worth having a section on electrical synapses.
David Martland 00:06, 16 Jan 2004 (UTC)
thread_title: Older edits

message: "Synapses define the circuits in which the neurons of the central nervous system interconnect."
was changed to "Synapses are circuits...." 
Synapses are functional contacts for communication between nearby cells. Most synapses are between adjacent neurons, but some synapses are from neurons onto other cell types such as muscle cells. Synapses are of two types: electrical synapses and chemical synapses. Electrical synapses provide cytoplasmic connections between adjacent cells where ions can carry charges from one neuron to another. Chemical synapses provide cell-to-cell communication that is mediated by neurotransmitters. A neurotransmitter is a chemical that is released from one neuron, moves to a nearby neuron, and acts to modulate the physiology of the target cell. Neurotransmitters often work by binding to receptor proteins on the surface of cells. However, some neurotransmitters pass through cell membranes and directly influence target proteins inside their target neurons. Structurally, synapses are usually regions of close contact between adjacent neurons. Most neurotransmitters are packaged into vesicles at the presynaptic side of synapses. Most neurotransmitter receptors are concentrated in post-synaptic densities on the post-synaptic side of synapses. When activated by neurotransmitters, neurotransmitter receptors typically change ion flow across the surface membrane of postsynaptic neurons. Neurotransmitter receptors can have other effects such as regulation of gene transcription and the regulation of synaptic plasticity (changes in the functional and structural properties of the synapses themselves). The interconnected networks of neuronal cell bodies, axons, synapses and dendrites can be thought of as circuits that carry signals using a mixture of chemical synapses, electrical synapses, action potential propagation, and signals in the form of graded potential changes at cell surface membranes. JWSchmidt 23:41, 29 Mar 2004 (UTC)
thread_title: Synapses and circuits

message: *"Synaptic strength is the amount of current, or more strictly the change in transmembrane potential of the synapse."
*"One regulatory trigger of synaptic strength involves the simple coincidence sensory stimuli and action potentials in the synaptically linked cells."
1) I'm not sure why these two "sentences" seem to have a charmed life on the synapse page. They both should be fixed. 
2) If you look in a neuroscience textbook (example) you will find discussion of synaptic strength mostly in the context of synaptic plasticity. I tried adding some basic information about synaptic plasticity. It was removed, leaving these two (above) problem sentences. 
In summary, the "Synaptic Strength" section needs help but I'm not sure I should make any more effort to help it. JWSchmidt 00:47, 30 Mar 2004 (UTC)
replies: text: I think all efforts should be made to ensure that this page has nothing to do with plasticity. We are currently trying to update the plasticity page, but I have been running around on the AMPAR page and NMDAR page trying to fix errors with respect to plasticity there. The only thing that you might want to mention is the p,N,q parameters (probability of release, number of neurotransmitters, and sensitivity of receptors) which characterize the 'strength' of a synapse. Paskari (talk) 17:49, 23 July 2008 (UTC)
thread_title: Synaptic Strength

message: Which is the average size of a synapse ? It is probably smaller than a micron since the neurons size is between 5 and 150 microns, but I would like to know their real size.
: It's hard to tell exactly what dimensions you're speaking of, but I'd bet you're asking about the distance between pre- and postsynaptic neurons. The gap is called the synaptic cleft and it is typically 20-30 nm across. Here's a nice visual. --David Iberri | Talk 22:09, Apr 13, 2005 (UTC)
:: What is the typical cross section area of a synaptic cleft? The volume?
::--Erland Lewin 10:25, 3 August 2006 (UTC)
thread_title:  Dimension of a synapse ? 

message: Hello, just wanted to tell you that I have drawn a few diagrams related to synapse. Please check the french version of the article :fr:Synapse. The pictures are on Commons.  Dake 13:13, 2 September 2005 (UTC)
replies: text: *I have a few comments about these diagrams: 1) The picture of a synapse is nice, but I think the one on the English article already is more complete and maybe more accurate and it is already annnotated directly, so I wouldn't suggest changing it. 2) The images of a neuromuscular junction are nice and I would suggest you put them in the NMJ article. However I did notice that the second image has no repetors on the postsynaptic surface! 3) The synapse article does not have a picture of an electrical synapse, and your looks nice, one thing I'm not sure about though is whether presynaptic Ca++ channels are important for electrical transmission and if not why are they in the diagram. 4) Finally, there are separate articles for action potentials and EPSPs. Also, why is the EPSP waveform so strange looking.  I think the images are of very good quality, but perhaps not as complete or accurate as they may be.  I'd normally be happy to comment on the French version of synapse to look for completeness/accuracy, but alas I don't speak French well enough to do so.  It  looks very thorough however.  Cheers, Nrets 14:00, 2 September 2005 (UTC)
thread_title:  New diagrams 

message: A common question is how many synapses are in the human brain. I suggest mentioning current estimates. It's 1000 trillion for a one year old baby, declining to about 500 trillion for an adolescent. Recent data indicates this number stays constant into adulthood, unlike earlier estimates stating it declined to 100 trillion. (Shore, Rima, Rethinking the Brain: New Insights into Early Development, Families and Work Institute, 1997) Joema 17:18, 21 December 2005 (UTC)
thread_title:  Include Number of Synapses in Human Brain 

message: As I claim on WP:FARC, this article no longer fulfils the criteria for being a Featured Article. Specifically, it does not cover the subject in adequate depth and breadth by today's standards, and lacks in references; specifically, it needs inline references. I believe these are serious shortcomings and that the article will be better served by being demoted rather than half-hearted attempts at fixing it just so it can barely scrape acceptance as an FA. It would be nice to be convinced that the article can be swiftly and impressively fixed, but will defend my proposal to demote in the absence of any such activity.
Regards,
Samsara (talk • contribs) 19:58, 21 May 2006 (UTC)
thread_title:  Featured article removal candidate 

message: Chemical synapse redirects here. Electrical synapse does not. Any thoughts? - Samsara (talk • contribs) 18:01, 24 May 2006 (UTC)
replies: text: This article basically describes a chemical synapse which is the "prototypical" synapse, electrical synapse has its own article. We could merge these? Nrets 18:57, 24 May 2006 (UTC)
replies: text: It would be cumbersome to the reader to have chemical, electrical, and immunological synapses all on the same page. Instead, each topic should have its own article. As "synapse" most often refers to the chemical sort, a redirect from Synapse to Chemical synapse would be in order. --David Iberri (talk) 03:48, 4 June 2006 (UTC)
replies: text: I've moved the page from synapse to chemical synapse per above. Now chemical, electrical, and immunological synapses have their own articles. --David Iberri (talk) 17:01, 21 June 2006 (UTC)
thread_title:  Chemical vs. electrical 

message: Synaptic Bouton is more or less orphaned, a stub, and really a part of a chemical synapse.  I say we add what little content it has to this article and redirect synaptic bouton here. --Selket 07:54, 1 February 2007 (UTC)
replies: text: Sound like a good plan. Nrets 17:56, 2 February 2007 (UTC)
thread_title:  Merge Synaptic Bouton 

message: Second Sentence
*The biological membrane of the two cells side each other across a slender gap, the narrowness of which enables signalling neurotransmitters to pass rapidly from one cell to the other by diffusion. This gap, which is about 20 nm wide, is known as the synaptic cleft. 
*Which 2 cells? --Parker007 06:20, 7 March 2007 (UTC)
thread_title:  Removal of sentences from the Anatomy and physiology  

message: Would it not be better just to have this at synapse instead of having a more specific name? The former just redirects here, so why not move it to the simpler name as has been done with other articles, e.g. biological reproduction. Richard001 01:53, 25 August 2007 (UTC)
replies: text: This was discussed before (check the history for this page, I think). The reason is that there are immunological synapses, electrical synapses, and chemical synapses, all of which are a type of synapse. Synapse redirects to Chemical synapse because when unqualified, "synapse" most often refers to the chemical variety. --David Iberri (talk) 15:49, 26 August 2007 (UTC)
thread_title: Move

message: "At an archetypal chemical synapse, such as those found at dendritic spines, a mushroom-shaped bud projects from each of two cells and the caps of these buds press flat against one another. At this interface, the membranes of the two cells flank each other across a slender gap, the narrowness of which enables signaling molecules known as neurotransmitters to pass rapidly from one cell to the other by diffusion. This gap, which is about 20 nm wide, is known as the synaptic cleft."
So do the caps really press flat against one another, or is there actually a gap between them? If there is a gap, how is it that the two really press flat against one another? If there is actually a gap, would it be accurate to say, then, that there is only the appearance of the direct physical contact via the membranes that's also suggested? 
I don't quite understand.
Is it that the membranes are pressed against one another, but contain a gap (or the synaptic cleft) within, or inside that zone of contact? The idea that one gets from the synapse illustration (for example, http://en.wikipedia.org/wiki/Image:SynapseIllustration2.svg and http://en.wikipedia.org/wiki/Image:Complete_neuron_cell_diagram.svg) is that there is no actual membrane contact, only a very close proximity that, nonetheless, precisely falls short of the two cells pressing against one another due to the synaptic cleft.
I admit that I am missing something, but perhaps this is because of the ambiguity inherent in the description supplied. Could someone please clarify this point, on the article page or even here?
-72.68.221.206 (talk) 20:39, 18 November 2007 (UTC)
replies: text: I've changed that ambiguity you mentioned. The projections don't physically touch each other, which results in the creation of the cleft. Hopefully this is clearer now. --Dpryan (talk) 04:24, 19 November 2007 (UTC)
replies: text: Why exactly do the two synapses not touch eachother, but stay at a casual distance of 20 nm? Is it because of the 'cell adhesion proteins'? Paskari (talk) 17:55, 23 July 2008 (UTC)
thread_title: The Anatomy Section: Huh?

message: I didn´t spot it in the article so my question is: Why does the presynaptic cell align with the postsynaptic cell in such an exact way? 
Kinda hard to find the correct words for it, so lets say we have a regenerating neuron that´s currently in the progress of remaking the connection with another cell after injury: 
How do they connect to each other in the first place? What makes the presynaptic terminal "connect"? Fernando Hulio (talk) 14:08, 8 July 2008 (UTC)
replies: text: I would suggest starting by looking at synaptogenesis.  Perhaps there should be a link to that page somewhere in this one. Xargque (talk) 16:21, 8 July 2008 (UTC)
thread_title:  Question about the alignment of the synapses 

message: I find computer scientists, when creating neural network simulators, create synapses with three attributes: a strength, a synaptic delay, and a synaptic duration. The strength value is self explanatory (albeit over simplified). The synaptic delay represents the axonal delay+delay from end of axon to axon buttons. The synaptic duration is the one that strikes me as a bit odd. I know that exocytosis is extremely rapid (<200 microseconds), and I know that the strength of a presynaptic synapse is characterized by the probability of vesicle release (p) and the number of release sites (N), but is there also a temporal component to synaptic strength? Do stronger synapses release their neurotransmitters for a longer period of time? I highly doubt this. Paskari (talk) 18:01, 23 July 2008 (UTC)
replies: text: When you start looking at network scale models you'll find that the math doesn't necessarily map perfectly onto the underlying individual neurons (e.g. you might model the neuron not as a series of compartments with conductances but as a black box). --Dpryan (talk) 19:41, 28 July 2008 (UTC)

text: The transmitter stays bound to the postsynaptic receptors for some amount of time (5 to 500 ms).  Plus, once the membrane has been depolarized, it has to relax back to resting potential with a certain time constant (which can also be on the order of tens of milliseconds).  Is that what you're wondering about? Xargque (talk) 17:22, 31 July 2008 (UTC)
thread_title:  Synaptic Duration 

message: There was a contradiction with the article Neuron in the numbers for the estimates of the number of synapses in the adult human brain. In the talk section above, #Include Number of Synapses in Human Brain and in the first edit concerning this way back in 23 December 2005 , this was given as 100-500 trillion. Then on 16 November 2006, someone added it in scientific notation, but got the number wrong, putting 15 instead of 14  and the next day, the numbers were changed from 100 to 500 trillion to 1,000 to 5,000 trillion. I've changed the numbers back to the way they were, making them the same as those given in Neuron. --121.45.173.99 (talk) 10:23, 3 August 2008 (UTC)
thread_title:  Number of synapses 

message: I have never heard of the term homotropic modulation or heterotropic modulation applied to synapses.  It is more common to refer to homosynaptic or heterosynaptic plasticity.  There were errors in the content of that section as well.  I'm not aware of any example where the size of vesicles is affected by the neuron's own activity or other neurons' activity.--Pkatz (talk) 15:08, 30 August 2008 (UTC)
thread_title:  Homotropic/Heterotropic vs Homosynaptic/Heterosynaptic 

message: I have boldy removed the refimprove tag from the article.  Synapses are the central topic in neuroscience, and are discussed thoroughly in every basic neuroscience textbook, so there is no problem in verifying most of the assertions in this article.  If there are specific assertions that you think require verification, please feel free to mark them with a "fact" tag. Looie496 (talk) 17:15, 15 September 2008 (UTC)
thread_title:  Removing refimprove tag 

message: I've added a quick paragraph about symmetry of synapses in the structure section. I've not sourced it yet, there's some stuff here http://thebrain.mcgill.ca/flash/capsules/pdf_articles/synapses.pdf plus some more content if the section gets expanded, including the history of the teriminology. There's already a reference to the chemical synapse being "asymmetric in structure and function" because the signalling is one way (although you might argue that autoreceptors mean that the process isn't exclusively one directional). However, as far as I can tell, this isn't the same as the structural symmetry of the synaptic membranes.Keepstherainoff (talk) 14:06, 20 July 2010 (UTC)
thread_title:  Symmetric and asymmetric synapses 

message: In cooperation with user Looie I have created a 60 seconds video clip on the basic processes of the chemical synapse.  This is a 13MB file.  Smaller resolutions (equals smaller size) is possible but video quality drops to rubbish.
I welcome any advice / critique on improving the clip  (I am not a neuroscientist, so please keep it simple).
Please leave a message on my user page if you think that another article could use a video clip to help WP users understanding the subject matter better.
--Cookatoo.ergo.ZooM (talk) 15:03, 9 October 2010 (UTC)
replies: text: Thanks for doing this! I have a very small suggestion, that I will leave at your talk page. --Tryptofish (talk) 19:06, 9 October 2010 (UTC)

text: Done.  The title has been changed to read "synapse".  --Cookatoo.ergo.ZooM (talk) 19:29, 9 October 2010 (UTC)
replies: text: Thanks! --Tryptofish (talk) 19:29, 9 October 2010 (UTC)
thread_title:  Video clips 

message: Astrocytes can help remove neurotransmitters, apart from the already enlisted 129.180.166.53 (talk) 15:04, 10 June 2012 (UTC)
thread_title:  Another mechanism to remove neurotransmitters 

message: Substituted at 11:25, 29 April 2016 (UTC)
thread_title: Assessment comment

message: What structure (force?) holds 2 neurons close together, but still separated in very small distance so that there will be functional synaptic cleft?  Nimelik 7. january 2018, 13:31  — Preceding unsigned comment added by Nimelik (talk • contribs) 11:34, 7 January 2018 (UTC)
replies: text: That's an interesting question, but it's really a matter of the larger scale structure of the living tissue. The presynaptic cell and the postsynaptic cell are each held in position by the other cells surrounding them (and in some cases there are extracellular proteins that anchor one cell to another, although I'm not aware of one that traverses the synaptic cleft), and there is extracellular fluid, so a given amount of extracellular fluid occupies the space between the two cells. During tissue development, there are growth factors that attract the presynaptic terminal to its postsynaptic target. --Tryptofish (talk) 20:26, 7 January 2018 (UTC)
replies: text: Try Wikipedia search: synaptic adhesion molecule 79.66.218.98 (talk) 22:03, 12 April 2019 (UTC)
thread_title:  synaptic cleft 

message: :The article says "The membrane added by the fusion process is later retrieved by endocytosis and recycled for the formation of fresh neurotransmitter-filled vesicles". Does this mean that the  membrane originally used by the vesicle is actually recycled or that some arbitrary portion of the cell membrane is harvested when a new vesicle is to be created? There are implications with each. Literal recycling would require something which marks the vesical membrane region as recyclable. If arbitrarily harvested then the recycling is figurative. 79.66.218.98 (talk) 22:13, 12 April 2019 (UTC)
thread_title:  Vesicle membrane recycling