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One more query to follow-up on: consider a circuit in which two nodes are connected by a conductance G. Let's call them node 0 and node 1, so the voltages at these nodes will be called v0 and v1. The current that leaves node 0 through g is (v0 - v1)*G and the current that leaves node 1 through g is ...

Thanks for the workaround!

This clinched it for me: For an electrically compact cell, Rm = Rin * surface area in cm2. Hadn't thought of that. Just to complete the above discussion: Rin = 43930 Mohm = 43930* 1e6 ohm So, Rm = Rin * surfacearea = 43930*1e6 ohm * 100*PI*1e-8 = 138065 ohm.cm2 which is very close to out expected va...

A seemingly very trivial problem, but I can't figure out whats going wrong with the below code for defining a vector: //Range MINS = 1.2 INCS = 0.05 MAXS = 5 objref vecs vecs = new Vector(((MAXS-MINS)/INCS)+1) print "vector Size: ", vecs.size() print "vector defined Size: ", (((M...

Hi Keivan, Happened to come across your post as I was also working on modeling extracellular fields and found the title interesting. I also ended up having to deal with LinearMechanism.... and yeah it seemed best avoided :p (atleast at first) You might find the following discussion useful: http://ww...

Then Rm at the particular potential at which the measurement was made = Di * Dv (read the Ds as upper case delta) is the slope resistance of the membrane. I suppose this is basically equivalent to the slope of an I-V curve - the way we determine input resistance? In that case, wouldn't it be Rin = ...

Oh ok... I think I see it now! The equation: c*(dy/dt) + g*y = b just involved scalar multiplications, and not the matrix multiplications that I mixed in. I suppose I just got into the flow of things seeing all the matrices, and when I had it on paper, matrix multiplication seemed the most natural w...

Sorry for bombarding you with posts, but here is one more: I am not sure I followed you entirely here: If you were to actually measure membrane resistance, you'd apply a small current and observe the resulting change of membrane potential. This would reflect 1/(total conductance of all ion channels)...

Thanks Ted. So far so good - I follow you till that point. I attempted such a derivation in that post under the head: APPENDED LATER - The 'correct' approach Only query being what I have posted in the next part there... Suppose we did go ahead with the 'gmat' matrix as in above modeldb files, then e...

That pretty much sums it up. Thanks. The membrane current and rest being more or less similar to what? I was referring to rest (as in calculated value of v, vext) being same whether gap junctions were implemented as NONSPECIFIC_CURRENT or ELECTRODE_CURRENT, and that only i_membrane would change. But...

Thanks Ted. That list of gap junction implementations is surely going to be handy for many of us. As for, NONSPECIFIC_CURRENT & ELECTRODE_CURRENT, I suppose it would be fair to conclude that the major difference results in the membrane current (i_membrane) and rest being more or less similar. Th...

For the last month or more, I have been trying my hand at using LinearMechanism. Despite having made some headway I am still some way off my goal. Currently, I am stuck with the following errors: "spFactor error: Zero Diagonal" & "spFactor error: Singular". But before going i...

Found the following post with a whole lot of info on ELECTRODE_CURRENT & NONSPECIFIC_CURRENT: http://www.neuron.yale.edu/phpbb/viewtopic.php?f=16&t=2475#p9807 The following, I believe, relates to a part of my query: Facts which apply to any section that has NEURON's extracellular mechanism: ...

I recently learnt that it is more appropriate to make use of ELECTRODE_CURRENT instead of NONSPECIFIC_CURRENT when extracellular mechanism is present. I went through the NEURON book and this is what I understood: ELECTRODE_CURRENT > Positive values of current would depolarize the cell > Above sugges...

That does explain a lot of what is happening. Thanks for the 'verdict' on the issue. Now that it is known I can work on managing my resources more thriftily. ... and yes in recent times I have begun to wonder whether it would be much better to have my simulations on Linux.... apart from this issue, ...