Implementing new Synapses

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Alexk

Implementing new Synapses

Post by Alexk »

Hi everyone,

I have been working with NEURON for a few weeks now and am therefore far from what you could call an expert. Therefore my apologies for maybe asking something basic, but i dont seem to find the error myself.

I am trying to implement NMDA and other synapse types into a simple model just to learn and get a grasp on it. Therefore I downloaded the ampanmda.mod used in "McTavish TS, Migliore M, Shepherd GM, Hines ML (2012) Mitral cell spike synchrony modulated by dendrodendritic synapse location" to start from somewhere. Subsequently i just replaced a standard synapse (ExpSyn) of a working model with the AmpaNmda synapse provided. However somehow I am not able to get it to work properly, meaning: the synaptic current persistently stays at zero. Thinking it might be due to the mg block i tried voltage clamping to something higher than the resting potential, which also did not work. Is there perhaps another way to initialize the synapse which differs from the standard way?

thanks a lot in advance,
best wishes,
Alex

Here my code:

Code: Select all


create soma, axon
access soma

soma{
	insert hh
}

axon{
	nseg = 10
    diam = 3.18
    L = 701.9
	insert hh
	insert pas
}

objref syn
syn = new AmpaNmda(.5)
// ExpSyn (works) or AmpaNmda (does not work)

objref stim
// -------------  tried VClamp to unblock Mg  --------------------------------
//objref vclamp
//vclamp = new VClamp(0.5)
//vclamp.dur[0]=200
//vclamp.amp[0]=-40

axon {
    stim = new IClamp(0.1)
    stim.del = 5
    stim.dur = 3
    stim.amp = 10
}

objref netcon
//            new NetCon(&source_v, synapse, threshold, delay, weight)
axon netcon = new NetCon(&v(1), syn,-40, 0, 1)

tstop = 20

//-------Graph----------------------	
objref isyn, vSoma, vAxon
isyn = new Graph()
isyn.size(0,tstop,-8,25)
isyn.addvar("syn.i",3,0)
isyn.save_name("graphList[0].")
graphList[0].append(isyn)


vSoma = new Graph()
vSoma.size(0,tstop,-100,50)
vSoma.addvar("soma.v(.5)",3,0)
vSoma.save_name("graphList[0].")
graphList[0].append(vSoma)

init()
run()

ted
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Re: Implementing new Synapses

Post by ted »

Alexk wrote:the synaptic current persistently stays at zero.
You're quite sure of that? Take adavantage of the interactivity of NEURON's graphs, especially autoscaling via "View = plot" (search for
view = plot
in the Forum; a good description is among the earliest posts).

So your code is working after all.
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