Talk:Dendrite

Here
Here is some information that would be useful to add to article eventually in the form of drawings:

There are several different patterns of dendrites:

adendritic spindle radiation spherical radiation stellate partial stellate laminar radiation planar offset multi cylindrical radiation conical radiation biconical radiation fan radiation

Also, if we zoom on a single dendrite, we can see that a group of synapses follows the following patterns:

variscosity filipodium simple spine sessile pedunculated branched spine claw ending brush ending thorny excrescence racemose appendage coralline excrescence

Perisomatic dendrites
I added a phrase about perisomatic dendrites - a feature unique to Betz cells (among pyramidal) AFAIK. Maybe there should be a short list of their somal surface localisation types, something like this:
 * Basal dendrites, leaving the cell at the base. Typical to the most pyramidal cells.
 * Apical denrite, a big single dendrite usually pointing to the pia mater, but not so in Martinotti cells.
 * Perisomatic dendrites, coming from almost any place of the soma. Typical to the Betz cells. (and maybe some other types?)

--CopperKettle 15:02, 26 February 2007 (UTC)

dendritic links to this page - dendritic could also refer to the dendritic cells of the immune system - there should at least be a disambiguation

Dendritic arbor
there is a reference to a 'dendritic arbor' but no definition as to what that is, could someone write a small definition for this please Paskari 10:40, 21 May 2007 (UTC)
 * Ok, done.UnderEducatedGeezer (talk) 17:40, 25 April 2016 (UTC)
 * Years later, there's still no clear explanation here of what "dendritic arbor" means. Can someone please define/explain this term in the article? There's some discussion of "arborization", but it's still not clear to this novice reader what either "dendritic arbor" or "dendritic arborization" means precisely when it is used in neurobiology literature (or this or other wikipedia articles). –jacobolus (t) 00:03, 30 December 2023 (UTC)

Strange Wiki Omission?
Wikipedia seems to be totally unaware that the term 'dendrite' is just as important (if not more important) in the fields of metallurgy and geology. It is the nucleation, growth and impingement of dendrites in liquid metals which determines many of the properties of finished products. —Preceding unsigned comment added by 86.171.9.200 (talk) 16:42, 3 May 2009 (UTC)


 * Well, we'll have an article about that just as soon as somebody who understands the topic writes one. I personally am open to changing this article to "dendrite (neural)" and adding a disambiguation page, once such an article exists. Looie496 (talk) 17:41, 3 May 2009 (UTC)

Sources!
This article needs to give more sources —Preceding unsigned comment added by 212.201.44.249 (talk) 07:08, 6 October 2009 (UTC)

The following citation is not publicly available (might not even exist): White, L (2013). Functional Microanatomy of Neurons. Duke University. — Preceding unsigned comment added by 198.0.135.11 (talk) 20:26, 15 June 2014 (UTC)

Length
The typical and maximal length of a dendrite should be in the article. Icek (talk) 21:26, 30 July 2010 (UTC)

Dendrites...allow "for a chemical signal to pass simultaneously to many target cells" is misleading?
The statement in the second section of the introduction at citation 3, "Dendrites provide an enlarged surface area to receive signals from the terminal buttons of other axons allowing for a chemical signal to pass simultaneously to many target cells." may be somewhat confusing, as it seems to suggest that it is the manifold dendrites that allow the presentation of a signal to many other neurons; but the cited reference goes on to say, "The axon commonly divides at its far end into many branches, each of which ends in a nerve terminal, so that the neuron’s message can be passed simultaneously to many target cells...". Shouldn't that be clarified? UnderEducatedGeezer (talk) 11:30, 20 March 2016 (UTC)
 * Well, it's really both, isn't it? Axon branching wouldn't help unless there was enough postsynaptic space to allow all the axon branches to have something to connect to.  Anyway, please feel free to revise the wording. Looie496 (talk) 14:32, 20 March 2016 (UTC)
 * Ok, done.UnderEducatedGeezer (talk) 10:39, 21 March 2016 (UTC)
 * But I really don't see how the multiplicity of dendrites at a neuron provides for ..."a chemical signal to pass simultaneously to many target cells.", as all that's needed is many target cells receiving signals from the many branches of a single axon in order to send an axons particular signal to many target cells simultaneously. Thus the postsynaptic space to allow all the axon branches to have something to connect to could simply be multiple neurons with even just one single dendrite on each neuron.  So it's the multiple branching of the axon that allows the presentation of a signal simultaneously to many target cells, and the branching of the dendrites that allow for many different signals to come into a neuron simultaneously or otherwise, which aren't the same thing.UnderEducatedGeezer (talk) 05:51, 3 April 2016 (UTC)

Action potential not (mostly!) propagated along DENDRITE?
I think the following sentence is not correct with respect to the conduction of a signal along the dendrite:  "The action potential propagates the electrical activity along the membrane of the dendrite to the cell body and then afferently down the axon to the terminal buttons where it crosses the synapse.[3]". Except for possible new findings of voltage gated ion pores at branch points in the dendritic arbor (yielding a weak saltatory conduction?), the spread of signal along dendrite membrane is solely passive, isn't it, no action potential otherwise involved? The rest of the indicated citation goes on to say about the axon, "...a local electrical stimulus of sufficient strength triggers an explosion of electrical activity in the plasma membrane that is propagated rapidly along the membrane of the axon and sustained by automatic renewal all along the way. This traveling wave of electrical excitation, known as an action potential,...".

I'm wondering if the section shouldn't be changed to something like, "This change in the membrane potential will passively spread along the dendrite and across the soma to the axon hillock, but becomes weaker with distance. If that potential is added to by additional signals, either the same signal quickly repeated (temporal summation) or from other input sources (spatial summation), and sums up to equal or exceed  a trigger voltage, an action potential will fire in the axon and successively re-strengthen the signal on its way down the axon to the terminal buttons where it crosses the synapse." Would something like that be ok?UnderEducatedGeezer (talk) 10:42, 3 April 2016 (UTC)


 * The sentence is misleadingly written, but the truth is somewhere in between. The original concept was that dendrites are purely passive, but research over the last decades has uncovered many cases of active signal amplification in dendrites, even to the extent of sometimes producing action potentials in distal dendritic branches.  However this is by no means a universal effect. Looie496 (talk) 20:03, 3 April 2016 (UTC)

Number of dendritic spines per neuron?
I was going to expand info from the most recent edit regarding number of spines per cell, until I realized there is an inconsistency between two different citations. One source for spines says a type of neuron can have 200,000 spines (note, max number is not 15,000 as indicated in most recent edit), but the other citation for branching says there can be as many as 100,000 inputs per neuron. (I'm assuming that if a cell has 200,000 spines then it's not limited to 100,000 inputs.) Here's what I was going to put, until I noticed the inconsistency: 'The quantity of spines on different types of neurons varies, as there are spiny and smooth neurons. Smooth neurons have few or no spines, whereas different types of spiny neurons can have from 15,000 to 200,000 spines per cell, each of which serves as a postsynaptic process for individual presynaptic axons.[5] Dendritic branching can be extensive and in some cases is sufficient to receive as many as 100,000 inputs to a single neuron.[3]' How to resolve the inconsistency?UnderEducatedGeezer (talk) 18:31, 25 April 2016 (UTC)