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