- #36
granpa
- 2,268
- 7
somasimple said:We have had already discussed about these instructive curves but DaleSpam contests any delay in the internode.
For my own, I accept facts.
you mean delay at the nodes?
somasimple said:We have had already discussed about these instructive curves but DaleSpam contests any delay in the internode.
For my own, I accept facts.
The B curve shows stairs that aren't horizontal => Delay.granpa said:http://www.pubmedcentral.nih.gov/pagerender.fcgi?artid=1392492&pageindex=8
it appears to me based on this that the ap from one node passes right through the next node without delay but has become by that time so spread out that it just appears to be the onset of the next ap which actually occurs (at that next node) after a 0.1 ms delay.
what do you figure the speed is?somasimple said:The B curve shows stairs that aren't horizontal => Delay.
A speed may be seen as fast when you compare it with a slow one.granpa said:further the speed through the internode appears to be so fast that it can't even be determined from the graphs. the measured 20 m/s being due almost entirely to the delay at each node.
800 to 1300 ms-1granpa said:what do you figure the speed is?
sounds about right. speed of sound in water being 1500 m/ssomasimple said:800 to 1300 ms-1
perhaps less.
somasimple said:The B curve shows stairs that aren't horizontal => Delay.
granpa said:whoa. I totally misunderstood you. I thought you were saying the horizontal parts of the B curve weren't really horizontal.
you also misundrestood me. when I said it (the B curve) seems to pass through without delay I mean it seems to become the A curve
I thought you were saying the horizontal parts of the B curve weren't really horizontal.
granpa said:maybe you've seen this before but this is really interesting:
http://www.pubmedcentral.nih.gov/pagerender.fcgi?artid=1392492&pageindex=7
and especially this:
http://www.pubmedcentral.nih.gov/pagerender.fcgi?artid=1392492&pageindex=8
the peak seems to move almost instantly the 2 mm from node to node (the amplitude decreasing to not quite half) with a considerable delay (slightly less than 0.1 ms) at each node which gives it a net speed of 20 m/s. (during the internode, wouldn't it have to be moving at or very close to the speed of sound?) (which is 1500 m/s in water)
after the delay, the beginning of the peak at one node coincides with the beginning of the downstroke of the previous internode. which actually seems to move backward.
the arrival of the peak at the node at the end of one internode seems to correspond to the beginning of the upstroke of the next internode.
This?which actually seems to move backward.
somasimple said:The A curve is based upon rising phases that vary with decays.
Average speed must be < 1500 ms-1 because of the dampening (decay).
Edit: I said it =>
somasimple said:This?
granpa said:this what?
which actually seems to move backward.
Sound is a wave and it strength decays with distance.granpa said:so it can't be a sound wave becaise it decays? hmmmm.
Update your flash player;granpa said:oh. yes, that is what I was referring to.
I'll try to watch your animation but my competer tends to freeze whenever I do.
Hmmm, no, it implies an effect we do not see on curves.granpa said:but the backward effect is the opposite of what you would expect. it returns the axon to its resting state.
or download it on your computer.somasimple said:Update your flash player;
http://www.adobe.com//downloads/
Yes it repeats. Just a working hypothesis to see the transition phases.granpa said:thanks. I did get to see it. I watched for about 20 seconds. it just repeats doesn't it?
If you do not see the expected prediction of a theory, change the facts or theory.granpa said:that is exactly what I would have expected but like I said the backward effect is exactly the opposite.
somasimple said:If you do not see the expected prediction of a theory, change the facts or theory.
somasimple said:We disagree how is the passive section and what is happening.
somasimple said:The models are two low pass filters and only the cutoff frequency will be changed without any phase change for such a signal. NO DELAY.[/url]
somasimple said:The passives sites must exhibit what the active are doing in both directions because they are passive.
granpa said:after the delay, the beginning of the peak at one node coincides with the beginning of the downstroke of the previous internode. which actually seems to move backward.
somasimple said:If the node is purely passive as expected you must have a backward effect
Delay in the internode propagation.What is the disagreement?
This does not tell us how they are connected.a resistance and capacity in parallel...
Phase shift is not equal to delay.Don't RC circuits have frequency dependent phase shifts? Also, the time course of a signal depends on the presence of all its Fourier frequencies, so wouldn't a frequency dependent reduction in amplitude (even without a phase shift for each Fourier component) produce a shape change in the time course anyway?
Graph it! It seems normal with a decay. (see the pictures I provided)surprising feature that the descending phase occurs earlier at the distal than at the proximal end of the internode
Ditto!Huxley and Stampfli said:This spread takes place with a finite velocity (not necessarily constant) so that graph B becomes later, and graph C earlier towards the distal end of each internode.
somasimple said:Granpa,
Make a drawing: I'm lost.
Hmmm, no: It is better to lock something to ensure the transmission. Locking something before the transmission will be the best source of problem and no transmission.Granpa said:imagine this: four nodes. nodes 1,2,3 and 4. nodes 3 and 4 would be locked (all nodes would normally be locked).
This is completely wrong. Each scientific theory has some limited domain of applicability. For example, Maxwell's equations do not model the orbits of planets nor does it model the photoelectric effect, such things are outside of its domain. Maxwell's theory of EM does not need to "describe all facts", it only needs to describe and link facts within its domain. The search for a "Grand Unified Theory" or "Theory of Everything" is ongoing, and even if such a theory were available it would likely be too cumbersome to apply to neurons.somasimple said:A theory must describe all facts and make logical links between them. ... Why are you reducing the field of discussion?
Sub-threshold activity, as the whole cable theory, describes a facet of a thing that has many others.
I have told you the model I support several times: the standard HH model and cable equation. Since these are the standard models used my mainstream scientists there are plenty of references describing in exhaustive detail their use and their experimental validation. You know that perfectly well since you have read many of these papers. What could I possibly put in a post than would be more informative that what you already have read? I have neither the time nor the inclination for such a pointless pursuit.somasimple said:Please choose the electric model that mimics this activity and give us some values?
I understand why you continuously refuse...
Langauge barrier? I do not think so.
That is not a problem. I have the same inclination.DaleSpam said:I have neither the time nor the inclination for such a pointless pursuit.
DaleSpam said:The HH model describes supra-threshold activity and does not include any propagation mechanism.
(sic)!The Hodgkin–Huxley model is a scientific model that describes how action potentials in neurons are initiated and propagated. It is a set of nonlinear ordinary differential equations that approximates the electrical characteristics of excitable cells such as neurons and cardiac myocytes.