print "*******************************************************************************"
print "*******************************************************************************"
print " THIS IS A PRELIMINARY VERSION !!!!!"
print " PLEASE CONTACT"
print " schaefer@sun0.mpimf-heidelberg.mpg.de"
print " FOR THE MOST RECENT ONE"
print "*******************************************************************************"
print "*******************************************************************************"
/* --------------------------------------------------------------
NEURON code to simulate BAC firing in compartmental models
of Layer 5 Pyramidal cells
for detailed description see Schaefer, Larkum, Sakmann, Roth
"Coincidence detection in pyramidal neurons is tuned by their
dendritic branching pattern" J. Neurophys. in press
-------------------------------------------------------------- */
strdef modelName, loadProgram, cellName, outputFile, cellPath, loadProgram
objref trunc, secR, fi,vC, mbSec
objref sh, axonal, dendritic, dendritic_only, initZone, stimSec
objref st, syn,trunc,mbSec, middleSec
create somaA,iseg,hill,myelin[2],node[2],dendA1_0
access somaA
steps_per_ms = 40
dt = 0.025
sprint(cellPath,"")
load_proc("nrnmainmenu")
// --------------------------------------------------------------
// passive & active membrane
// --------------------------------------------------------------
spA = 2 // increase in membrane area due to spines
ra = 80
global_ra = ra
rm = 30000
c_m = 0.6
cm_myelin = 0.04
g_pas_node = 0.02
v_init = -70
celsius = 34
Ek = -90
Ena = 60
gna_dend = 27
gna_node = 30000
gna_soma = 54
gna_myelin = 80
gkv_axon = 3000
gkv_soma = 600
gkv_dend = 30
gca_dend =1.5
gkm_dend =.1
gkca_dend=3.25
gca_soma = 3
gkm_soma = 0.2
gkca_soma = 6.5
gka_soma = 0.06
gka_dend = 0.02
gka_slope = 0 // no gradient
tauR = 80
caiExp = 4
rA = 0.05
rB = 0.1
// --------------------------------------------------------------
// Low Threshold Ca Channel to reproduce frequency effect (Larkum, Kaiser, Sakmann, PNAS,1999)
// --------------------------------------------------------------
vh1_it2=56
vh2_it2=415
ah_it2=30
v12m_it2=45
v12h_it2=65
am_it2=3
vshift_it2=10
vm1_it2=50
vm2_it2=125
it2_init=0.0005
gca_init=4.5
// --------------------------------------------------------------
// initiation zone in the dendrite
// with slightly elevated Ca conductance densities
// --------------------------------------------------------------
proc InitZone() {
mbSec.sec distance(0,1)
forall for(x) if(distance(x) <100) {
gbar_sca = gca_init
gcabar_it2 = it2_init
}
}
// --------------------------------------------------------------
// replace init procedure to have sufficiently long prepulse
// --------------------------------------------------------------
proc init() {local saveDt, i
finitialize(v_init)
fcurrent()
saveDt = dt
dt = 10
for i=0,99 fadvance()
dt = saveDt
}
// --------------------------------------------------------------
// Axon geometry
//
// Similar to Mainen et al (Neuron, 1995)
// --------------------------------------------------------------
n_axon_seg = 5
proc create_axon() {local somaArea
create iseg,hill,myelin[n_axon_seg],node[n_axon_seg]
somaA {
somaArea=0
for(x) somaArea+=area(x)
equiv_diam = sqrt(somaArea/(4*PI))
}
iseg {
pt3dclear() pt3dadd(0,0,0,diam) pt3dadd(0,-1000,0,diam)
L = 15
nseg = 5
diam = equiv_diam/10
}
hill {
pt3dclear() pt3dadd(0,0,0,diam) pt3dadd(0,-1000,0,diam)
L = 10
nseg = 5
diam(0:1) = 4*iseg.diam:iseg.diam
}
for i=0,n_axon_seg-1 {
myelin[i] { // myelin element
pt3dclear() pt3dadd(0,0,0,diam) pt3dadd(0,-1000,0,diam)
nseg = 5
L = 100
diam = iseg.diam
}
node[i] { // nodes of Ranvier
pt3dclear() pt3dadd(0,0,0,diam) pt3dadd(0,-1000,0,diam)
nseg = 1
L = 1.0
diam = iseg.diam*.75 // nodes are thinner than axon
}
}
somaA connect hill(0), 0.5
hill connect iseg(0), 1
iseg connect myelin[0](0), 1
myelin[0] connect node[0](0), 1
for i=0,n_axon_seg-2 {
node[i] connect myelin[i+1](0), 1
myelin[i+1] connect node[i+1](0), 1
}
}
// --------------------------------------------------------------
// Spines
// --------------------------------------------------------------
proc add_spines() {
// increase all dendritic conductances by factor spA
// increase dendritic cm and g_pas by same
// to account for increase in membrane area without changing distances etc
forsec dendritic_only {
cm *=spA
g_pas *=spA
gbar_na *=spA
gbar_kv *=spA
gbar_km *=spA
gbar_kca *=spA
gbar_sca *=spA
gbar_kap *=spA
gcabar_it2*=spA
}
}
// --------------------------------------------------------------
// Initialization routines
// --------------------------------------------------------------
proc init_cell() {
// passive
forall {
insert pas
Ra = ra
cm = c_m
g_pas = 1/rm
e_pas = v_init
}
// exceptions along the axon
forsec "myelin" cm = cm_myelin
forsec "node" g_pas = g_pas_node
// active
// axon
forall insert na
forsec "myelin" gbar_na = gna_myelin
forsec "hill" gbar_na = gna_node
forsec "iseg" gbar_na = gna_node
forsec "node" gbar_na = gna_node
forsec "iseg" { insert kv gbar_kv = gkv_axon }
forsec "hill" { insert kv gbar_kv = gkv_axon }
// dendrites
forsec dendritic_only {
gbar_na = gna_dend
insert kv gbar_kv = gkv_dend
insert km gbar_km = gkm_dend
insert kca gbar_kca = gkca_dend
insert kap gkabar_kap = gka_soma
insert sca gbar_sca = gca_dend
insert it2 gcabar_it2=0
insert cad2
}
// soma
somaA {
gbar_na = gna_soma
insert kv gbar_kv = gkv_soma
insert km gbar_km = gkm_soma
insert kca gbar_kca = gkca_soma
insert kap gkabar_kap = gka_soma
insert sca gbar_sca = gca_soma
insert cad2
}
forall if(ismembrane("k_ion")) ek = Ek
forall if(ismembrane("na_ion")) {
ena = Ena
vshift_na = -5
}
forall if(ismembrane("ca_ion")) {
eca = 140
ion_style("ca_ion",0,1,0,0,0)
vshift_ca = 10
}
// ca diffusion and kca parameters
taur_cad2 = tauR
caix_kca = caiExp
Ra_kca = rA
Rb_kca = rB
InitZone()
add_spines()
}
// --------------------------------------------------------------
// loading cell
// --------------------------------------------------------------
proc load_3dcell() {
// $s1 filename
aspiny = 0
forall delete_section()
xopen($s1)
access somaA
forsec "axon" delete_section()
dendritic = new SectionList()
// make sure no compartments exceed 20 uM length
forall {
if(nseg < L/20) { print secname(), " not accurate" nseg=L/20+1 }
dendritic.append()
}
dendritic_only = new SectionList()
forsec dendritic dendritic_only.append()
somaA dendritic_only.remove()
}
// --------------------------------------------------------------
// Main Loading procedure
// --------------------------------------------------------------
proc LoadNInit() {
sprint(loadProgram,"%s.nrn",$s1)
load_3dcell(loadProgram)
create_axon()
init_cell()
}
// --------------------------------------------------------------
// setting stimuli
// --------------------------------------------------------------
st = new IClamp(.5)
syn = new epsp(1)
proc IatSoma() {
st=new IClamp(.5)
st.del = 1005.1
st.dur = 5
st.amp = 1.2
}
// EPSP : f(t) = (1-exp(-t/chi1)) * exp(-t/chi2)
// mit chi1 = 0.5 -2 ms und chi2 = 2-8 ms
proc EPSPAtDend() {
mbSec.sec {
syn = new epsp(1)
syn.tau0 = 0.8
syn.tau1 = 4
syn.onset = 1007.1
syn.imax = 0.5
}
}
// ----------------------------------------------------------------
// Run Routine
// ----------------------------------------------------------------
proc DoIt() {local i, j
init()
for i=0,999 {
for j=0,0.1/dt-1 fadvance()
}
}
forall delete_section()
cellName="d980329a-1"
printf("%s is the current cell\n",cellName)
LoadNInit(cellName)
IatSoma()
EPSPAtDend()
// --------------------------------------------------------------
// finally opening all graphs and panels
// --------------------------------------------------------------
xopen("Display.ses")
// the structure of this program was inspired by Mainen/Sejnowski
// http://www.cnl.salk.edu/~zach/source/pat-demo.tgz
print "*******************************************************************************"
print "*******************************************************************************"
print " THIS IS A PRELIMINARY VERSION !!!!!"
print " PLEASE CONTACT"
print " schaefer@sun0.mpimf-heidelberg.mpg.de"
print " FOR THE MOST RECENT ONE"
print "*******************************************************************************"
print "*******************************************************************************"
