I'm wondering if the earlier currents could affect neurodevelopment. And they are generated endogenously , exogenously or fired by other organs like beating heart?
I am not sure I can help you, but, I think currents are not as important to early development as you might think. If you think about the blastocid, it starts out as only a couple of cells, and then develops by progressive differentiation and morphing of cell relationships. The brain is not the first part of the body to grow, and so we can be fairly sure that the heart is beating before much brain development has happened. I suspect that the hypothalmic system matures enough to supply stimulation for the heart as part of the expansion of the brain tube, but the tube itself is very limited in its extent. As far as I know the placental barrier determines how much encroachment there is between the exogenous systems of the mother or egg, and the blastocid, and so there is little opportunity for that to "Kickstart" the fetal heart except through hormonal release.
Thank you very much! And I know it's very difficult since we do not have enough refference. As matter of fact, I just feel it interesting and I guess the earlier currents might induced by the heart when neural crest cells migrate to the heart or it's just a spontaneous process of the nervous system and there may exist some kind of cells in the CNS which are responsible to start it. Of course, it's just my opinon and far from science. It's very kind of you, and good luck!
I think however that the ion channels in the cells that make up the body are not limited to the Neurons, and that therefore there are ion currents, long before the first neuron is formed. I think it was Patricia Churchland, that in 2005 reminded us that there are no DNA genes that design neurons. Neurons are just a differential development mediated by the repetitive chemical patterns detected by the cell, that are used as a sort of map of the state and location of the cell, in comparison to the surrounding cells. This means that all of the early cells in the blastocid are likely to have precursor options that might make them neurons once differentiation to neurons becomes practical. Which means that they will all have rudimentary ion channels, and will all have a sensitivity to the epigenetic patterns around them. Understanding the ion channels of the plenipotential Stem Cell, is, I think a good topic for research. Interesting enough, you can create a plenipotential stem cell, simply by introducing 4 factors to any cell, in the body.
How this interacts with the new theory that the Genome includes control codes that determine the stimulus and timing for each genome to be expressed, is I think a new study, that has lots of potential. What I think happens is that the factors which I think came from reproductive science, reset the cell, to it's earliest non-unique state, including regrowing the telemeres, and then start the clock again.
I have a theory that when multi-cellular organisms became possible it was partly because they gave up the plenipotentiary possibility that any cell could start a new organism, to experience sex instead, and then, because of that were able to specialize non-plenipotentiary stem cells into specific roles.
Graeme Smith 's view appears to be most appropriate as far as i stretch my imagination although more references/studies may be required before accepting it.
Developing a theory needs just observation (the facts are all around us) and the problem is not accepting but using it. May be it's the better way for proving it.