This paper would suggest that it does occur in-vivo:

https://www.jneurosci.org/content/24/49/11127

Could still be an artefact of the intracellular solution used during in-vivo patch clamp (Ca2+ concentration for example). How common it is in-vivo I am not sure. Improved fluorescent voltage sensors could help answer this question without perturbing intracellular ion concentrations.

Thank you very much Daniel Müller-Komorowska for the reference !

Yes; very simple: had you ever banged your elbow? the sensations is lasting and

unique, backward action potentials from perpheral nerves. What you do? you rub it creating foward action potentials to mask the unpleasant tingling and pain

Vera Maura Fernandes de Lima the question was about dendrites and technically it is not like peripheral nerves.

Back propagation can occur where/when there is a stimulus and local conditions that satisfy a triggering.

The question asks about action potentials, dear Bernard.

Dear Lora if you want to be a neuroscientist, learn the jargon and think before asking a question, orthodromic and antidromic propagation are jargon words. and yes it valid for synaptic transimission also.

Well, thank you for your reply Vera Maura Fernandes de Lima but I am a neuroscientist, still, I do not pretend to know everything and this is why I am asking: to learn.

My question was indeed about dendrites where distribution in voltage-gated ionic channels and intracellular calcium stores is quite different from the one in the axon. This is why dendrites may not be able to conduct action potentials. In vitro, back-propagating action potentials (see ref for the jargon words) are commonly observed but I was wondering if it is a usual mechanism in vivo. As for LTP easily observed in vitro, the process still needs to be proven in vivo in numerous brain structures.

https://pubmed.ncbi.nlm.nih.gov/8876249/

Article Synaptic Depolarization Is More Effective than Back-Propagat...

https://pubmed.ncbi.nlm.nih.gov/19864442/

https://pubmed.ncbi.nlm.nih.gov/10588751/

Article Analogue modulation of back-propagating action potentials en...

For LTP in vivo look at these, dear Lora:

Evolution of interactions between brain structures during an epileptic seizure in a kindled rat

• January 1989
• J. Pijn
• P. Vijn
• 📷Fernando Lopes da Silva
• 📷Vera Maura Fernandes de Lima

The role of hippocampal commissures in the interhemispheric transfer of epileptiform afterdischarges in the rat: a study using linear and non-linear regression analysis

• January 1991
• Electroencephalography and Clinical Neurophysiology 76(6):520-39
• DOI:
• 10.1016/0013-4694(90)90003-3
• Source
• PubMed
• 📷Vera Maura Fernandes de Lima
• Jan Pieter Pijn
• 📷Carlos Filipe
• 📷Fernando Lopes da Silva

there is even a mathematical model explaining it in Hodkin and Huxley membrane terms:

Mathematical model of the CA1 region of the rat hippocampus

• October 1998
• Physics in Medicine and Biology 43(9):2631-46
• Follow journal
• DOI:
• 10.1088/0031-9155/43/9/014
• Source
• PubMed
• 📷Antonio Almeida
• 📷Vera Maura Fernandes de Lima
• 📷Antonio Fernando Catelli Infantosi

about channels recording in glia you can see this:

Patch-clamp experiments at isolated cells and in intact tissue of the chicken retina correlated to potassium channels and the retinal spreading depression

• December 1997
• Electrochimica Acta 42(20):3231-3240
• Follow journal
• DOI:
• 10.1016/S0013-4686(97)00196-5
• W. Hanke
• 📷Mario Mezler
• S. Brand
• Show all 6 authors
• 📷Vera Maura Fernandes de Lima

and in the spirit on improving your education here goes;

drome definition, a combining form meaning “running,” “course,” “racecourse” (hippodrome); on this model used to form words referring to other large structures ...

the origin means running in a line

ortho and anti you can google yourself

I wasn't saying that orthodromic and antidromic were incorrect, I know these words thank you. I just wanted to highlight that "back-propagating APs" are commonly used therms and that you didn't have to be condescending, just as you are again.

And for your answer on LTP Vera Maura Fernandes de Lima , if you read again my message, I said that it wasn't proven (yet) in various brain structures (while it is commonly found in vitro), and not that it doesn't exist in vivo

Dear Lora L Martucci ,

If one accepts that there is an AP in small unmyelinated fibres then it is acceptable to consider dendrites as very small unmyelinated fibres and therefore suitable for propagation.

But in this case the AP seems almost immobile but already sufficient to transmit a message/signal.

Dear Lora I measured it (LTP) in vivo and gave you the reference to the papers, bye bye

Dear Bernard Delalande ,

Thank you for your answer,

What do you mean by "the AP seems almost immobile"?

If you know any references showing in vivo AP in dendrites, I would be happy to look at it,

Many thanks,

Best regards

Dear Lora L Martucci ,

We are told that unmyelinated neurons are able to transmit (propagate) an event called AP.

It is said that the speed is related to the diameter of the fibre.

It is easy and also logical to conclude that for dendrites that are unmyelinated and very small in diameter that the velocity is very low.

It is also logical to have the same conclusion by the geometry of the dendrite itself. An AP has a duration and therefore occupies a physical length on the axon or dendrite. In the case of the dendrite, the AP has little room to express itself in its entirety.

It becomes clear in this particular case that it is not even necessary for the AP to be fast.

It would even be possible (cheeky!) that at the level of the dendrites, it is rather a proto AP than a real AP.

It is not always necessary to have references when our argument is logical and not very disputable.

Yours sincerely,

Bernard

Data Spatio-temporal profile of ion channel activation

If you watch this short video which is a simulation of a proto PA, you can see that the potential moves over time away from its place of emission (to either side or back and forth). This is what can be observed in a dendrite at a slightly larger scale.

Thank you for your detailed response Bernard Delalande !

Hello Lora,

It is an interesting question, because for many years we could not prove it directly (it needs to record both soma and dendrites in-vivo at the same time). But from what we knew in ex-vivo electrophysiology, there was no reason why it could not happen.

Thankfully it was observed recently with new imaging methods. You can check those references: DOI: 10.7554/eLife.49145 & DOI: 10.1038/s41586-019-1166-7

Cheers and good luck!

Thank you Sylvain Rama !

Indeed, along with literature, I usually found that dendrites were too thin for patch-clamping so the change in activity was preferentially observed indirectly thanks to imaging such as calcium imaging.

These articles seem very interesting, thank you very much for sharing the references !

Cheers !

Of course, there are dendritic back-propagating action potentials (bpAPs), in vivo, but it is true that they are rather difficult to measure, as simultaneous measurements are required.

You can find a few dual-patch (soma+dendrite) or Ca2+ imaging studies, but they remained certainly less detailed (dual-patch) or temporally inaccurate (Ca2+).

Recently, Adam Cohen (Harvard) showed a representative figure in his newest paper (https://advances.sciencemag.org/content/7/19/eabe3216) as a feasibility study to monitor bpAPs by using GEVIs (voltage indicators), which can be now applied both in vitro and in vivo.

In my opinion, the question is not so much whether they exist, but what their exact role is. According to several hypotheses, bpAPs are considered to be the precursors and promoters of spike-time-dependent synaptic plasticity.

Thank you very much Domokos Meszéna for your detailed answer.

Also, thank you for this very recent reference!