Inhibitory control of motoneuron excitability (Venugopal et al 2011)

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Accession:258234
A two-compartment model for a motor neuron following chronic spinal cord injury with excessive dendritic persistent Ca2+ current.
Reference:
1 . Venugopal S, Hamm TM, Crook SM, Jung R (2011) Modulation of inhibitory strength and kinetics facilitates regulation of persistent inward currents and motoneuron excitability following spinal cord injury. J Neurophysiol 106:2167-79 [PubMed]
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Model Information (Click on a link to find other models with that property)
Model Type:
Brain Region(s)/Organism:
Cell Type(s):
Channel(s):
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: MATLAB; XPP;
Model Concept(s):
Implementer(s): Venugopal, Sharmila [vsharmila at g.ucla.edu];
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SCIMN
readme.txt
desktop.ini
SVenugopal_SCI_Motorneuron.m
VSmn.ode
VSmn_inh.ode
                            
# Two-Compartment Motoneuron Model
# Sharmila Venugopal - svenugopal10@gmail.com
# Cite: S Venugopal et al., J Neurophysiology, 2011

# Ca concentration in micromoles/liter
#
# version for computing bifurcation diagrams
#
#soma equations

dvs/dt=(Iramp-sgna*snaminf(vs)**3*snah*(vs-(vna+vrest))-sgca*scam**2*scah*(vs-(vca+vrest))-sgk*sn**4*(vs-(vk+vrest))-perkca*sgkca*(sca**p/(kd**p+sca**p))*(vs-(vk+vrest))-gl*(vs-(vl+vrest))+gc*(vd-vs)/parea)/cm
dsnah/dt=(snahinf(vs)-snah)/snahtau(vs)
dsn/dt=(sninf(vs)-sn)/sntau(vs)
dscam/dt=(scaminf(vs)-scam)/camtau
dscah/dt=(scahinf(vs)-scah)/cahtau
dsca/dt=-f*alpha*sgca*scam**2*scah*(vs-(vca+vrest))-f*kca*sca

#dendrite equations

dvd/dt=(-dgcas*dcas*(vd-(vca+vrest))-pernap*gNaP*mnap*hnap*(Vd-(vna+vrest))-perkca*dgkca*(dca**p/(kd**p+dca**p))*(vd-(vk+vrest))-gl*(vd-(vl+vrest))+gc*(vs-vd)/(1.0-parea))/cm
ddcas/dt=(dcasinf(vd)-dcas)/dcastau
ddca/dt=-f*alpha2*dgcas*dcas*(vd-(vca+vrest))-f*kca*dca
dmnap/dt=(minfnap(Vd)-mnap)/taunap
dhnap/dt=(hinfnap(vd)-hnap)/naptau



#
# soma functions
snaminf(vs)=1.0/(1.0+exp(-(vs-snamth)/snamslp))
snahinf(vs)=1.0/(1.0+exp((vs-snahth)/snahslp))
snahtau(vs)=snahc/(exp((vs-snahv)/snaha)+exp(-(vs-snahv)/snahb))
sninf(vs)=1.0/(1.0+exp(-(vs-nth)/nslp))
sntau(vs)=nc/(exp((vs-nv)/na)+exp(-(vs-nv)/nb))
scaminf(vs)=1.0/(1.0+exp(-(vs-camth)/camslp))
scahinf(vs)=1.0/(1.0+exp((vs-cahth)/cahslp))

# dendrite functions
dcasinf(vd)=1.0/(1.0+exp(-(vd-dcasth)/dcasslp))
minfnap(Vd)=1/(1+exp(-(vd-thetamnap)/Kmnap))
hinfnap(vd)=1/(1+exp((vd-thetahnap)/Khnap))


# bifurcation parameter
p iapp=0,itonic=0.5

Iinh=gi*s*(vd-vi)
gi=ggb+ggl
p s=2, vi=-100
p ggb=0.01,ggl=0.01

# common parameters
p vna=115.0,vk=-20.0,vl=0.0,vca=140.0,vrest=-60.0,cm=1.0,gl=0.51,
p p=1,kd=0.2,f=0.01,kca=2.0,alpha=0.009

# soma parameters
p sgna=80.0,snamth=-35.0,snamslp=7.8,snahth=-55.0,snahslp=7.0
p snahv=-50.0,snaha=15.0,snahb=16.0,snahc=30.0
p sgk=100.0,nth=-28.0,nslp=12.0,nv=-40.0,na=40.0,nb=50.0,nc=7.0
p sgca=14.0,camth=-30.0,camslp=5.0,camtau=4.0
p cahth=-45.0,cahslp=5.0,cahtau=40.0
#p sgkca=5.0
p sgkca=6

# dendrite parameters
p dgcaf=0.3
p dcasth=-39.0,dcasslp=7.0,dcastau=40.0
p dgk=0.0

# coupling parameters
p gc=0.1,parea=0.1
#p gc=0.08,parea=0.1

# conductance percentage factors
p perkca=1.0, perslca=1.0

# conductances sensitive to SCI
p dgkca=1.0
p gnap=0.1
p dgcas=0.25
p gpratio=1.772
p alpha2=0.009
p percap=1
p pernap=1
#=================================================================================================
#=================================================================================================
#=================================================================================================
#=================================================================================================
#p Itonic=0	
# Setting Itonic=0.5 helps AUTO find Hopf on the lower branch of S-shaped nullcline
#=================================================================================================
#=================================================================================================
#=================================================================================================
#=================================================================================================
p taunap=40
p naptau=1000
p thetamnap=-48,Kmnap=3,thetahnap=-35,Khnap=6,taumxnap=10000,Tmnap=5000

--------
Iramp=offsetr+scaler*(t-tonr)*(heav(t-tonr)*heav(toffr-t))+2*scaler*(tswitchr-t)*(heav(t-tswitchr)*heav(toffr-t)) 
par offsetr=0
par scaler=0.005
par tonr=0
par toffr=10000
par tswitchr=4000
--------
# soma initial conditions
vs(0)=-57.34
snah(0)=0.5829
sn(0)=0.1239
scam(0)=0.004199
scah(0)=0.9219
sca(0)=0.0001406
# dendrite initial conditions
vd(0)=-56.64
dcas(0)=0.08493
dca(0)=0.01724
#

aux I=Iramp
aux SK=-perkca*dgkca*(dca**p/(kd**p+dca**p))*(vd-(vk+vrest))
aux LCa=dgcas*dcas*(vd-(vca+vrest))

#
#xpp formatting
@ TOTAL=10000,DT=0.05,
@ MAXSTOR=600000,BOUNDS=600000,method=qualrk
@ xlo=0,xhi=10000,ylo=-60,yhi=40,nplot=2,yp2=I
done

#Potential values of parameters that give a slightly bizzare behavior suggesting hyper-excitable dendrites and persistent plateau activation - Dec/04/2009
#dgcas-0.3
#gnap-0.15
#dgkca-1.3
#sgkca-25
#taunap-200