look at the currents in the neuron connected with a ExpSyn

The basics of how to develop, test, and use models.
Post Reply
menica
Posts: 71
Joined: Wed Sep 02, 2015 11:02 am

look at the currents in the neuron connected with a ExpSyn

Post by menica »

I am starting with neuron. I am trying to make a code to connect two neurons trough an exitatory synapse and look at the Na, k and pump currents.
I can visualize the na and k currents in the presynaptic neuron, but seems that the signal does not arrive to the post synaptic dendtrite.

This is what i want to model:

//1.the pre is at rest
//to maintain the rest na channel and k channel working to move na out of the cell and k inside cell

//2.if there is a signal neurotransmitter binds receptor and happens this:
//in the axon near the soma na enter the cell
//na k pump try to restore equilibrium

//3. signal travel in the neuron and arrive at the end of the axon

//4. processes activated by Ca dynamics -> release neurotransmitters in the cleft

//5. signal arrives at the dend of the postsynaptic neuron

//6. plot currents pre and post

I am at the beginnign, so i am trying to do the thing step by step
until now, this is the part of code that gives me the problem:

Code: Select all

[load_file("nrngui.hoc")

//to plot
objectvar g[20]			// max 20 graphs
ngraph = 0

proc addgraph() { local ii	// define subroutine to add a new graph
				// addgraph("variable", minvalue, maxvalue)
	ngraph = ngraph+1
	ii = ngraph-1
	g[ii] = new Graph()
	g[ii].size(0,tstop,$2,$3)
	g[ii].xaxis()
	g[ii].yaxis()
	g[ii].addvar($s1,1,0)
	g[ii].save_name("graphList[0].")
	graphList[0].append(g[ii])
}

// crate control menu
nrncontrolmenu()	
	
//define sistem: create pre compartment
objectvar pre, post
pre = new SectionList()
post   = new SectionList()
forall pre.append()
forsec "p" post.append()
forsec "p" pre.remove()

// geometry
create soma ,psoma
create dend, pdend
create axon, paxon

connect dend(1), soma(0)
connect soma(1), axon(0)
connect pdend(1), psoma(0)
connect psoma(1), paxon(0)

//inital conditions
dt=0.025
tstop = 10 
runStopAt = tstop
steps_per_ms = 1/dt
v_init = -65
celsius = 36

//concentration ion outside
k0_out = 5
na0_out = 145
ca0_out = 2.5
//osmout0 = k_out+na_out+ca_out

//concentration ion inside pre 
k0_inpre = 140
na0_inpre = 10
ca0_inpre = 2e-4

//concentration ion inside post ( osmout - 2*nai0_na_ion - 3*cai0_ca_ion)/2
k0_inpost = 140  
na0_inpost = 10
ca0_inpost = 2e-4

//common properties compartments
forall {
  diam=10
  L=10
  nseg=1
}

// membrane mechanisms in pre

dend{
insert pas
  g_pas=1/5000
  e_pas=v_init
}

// insert current injection at the end of the soma
access soma
objectvar stim		
soma stim = new IClamp(.9)	  
stim.del = 1  //10 nmda
stim.dur = 2		
stim.amp = 2

soma{
insert pas
  g_pas=1/5000
  e_pas=v_init
}

axon{
insert hh2
	ek = -90
	gnabar_hh2 = 0.1
	gkbar_hh2 = 0.03
}

//insert syn excitatory
objref ncl
ncl = new List()
objectvar synE
pdend synE = new ExpSyn1(0.1)				
axon ncl.append(new NetCon(&v(1), synE, 10, 1, 0))

// membrane mechanisms in post
psoma{
insert pas
  g_pas=1/5000
  e_pas=v_init
}
paxon{
insert pas
  g_pas=1/5000
  e_pas=v_init
}
pdend{
insert hh2
	ek = -90	
	gnabar_hh2 = 0.1
	gkbar_hh2 = 0.03	
}

ddgraph("axon.v(0.5)",-90,40)
addgraph("pdend.v(0.5)",v_init-50,v_init+20) 
addgraph("pdend.ina(0.5)",-2,2)   //(0.99)
addgraph("axon.ina(0.5)",-2,2)     //(0.5)
addgraph("pdend.ik(0.5)",-2,2)   //(0.99)
addgraph("axon.ik(0.5)",-2,2)     //(0.5)]

The currents plotted for the postsynaptic neuron are just a straight line
same hint?

thanks
Menica
ted
Site Admin
Posts: 5810
Joined: Wed May 18, 2005 4:50 pm
Location: Yale University School of Medicine
Contact:

Re: look at the currents in the neuron connected with a ExpS

Post by ted »

First, let me start by thanking you for your interest in using NEURON, and acknowledging the time and effort that you have put into writing the code that you posted on the Forum. It is best if we continue this discussion by email because it is likely to involve many details that would not necessarily be relevant to other Forum readers. I will send you a message shortly.
Post Reply