Modeling interactions in Aplysia neuron R15 (Yu et al 2004)

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"The biophysical properties of neuron R15 in Aplysia endow it with the ability to express multiple modes of oscillatory electrical activity, such as beating and bursting. Previous modeling studies examined the ways in which membrane conductances contribute to the electrical activity of R15 and the ways in which extrinsic modulatory inputs alter the membrane conductances by biochemical cascades and influence the electrical activity. The goals of the present study were to examine the ways in which electrical activity influences the biochemical cascades and what dynamical properties emerge from the ongoing interactions between electrical activity and these cascades." See paper for more and details.
1 . Yu X, Byrne JH, Baxter DA (2004) Modeling interactions between electrical activity and second-messenger cascades in Aplysia neuron R15. J Neurophysiol 91:2297-311 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Neuron or other electrically excitable cell;
Brain Region(s)/Organism:
Cell Type(s): Aplysia R15 bursting neuron;
Channel(s): I Na,p; I Na,t; I N; I A; I K; I h; I K,Ca; I Sodium; I Calcium; I Potassium; I A, slow;
Gap Junctions:
Receptor(s): D1; D2; 5-HT1; 5-HT2; 5-HT4; 5-HT3; Dopaminergic Receptor;
Gene(s): D1 DRD1A; D2 DRD2;
Transmitter(s): Dopamine; Serotonin;
Simulation Environment: XPP;
Model Concept(s): Action Potential Initiation; Activity Patterns; Bursting; Ion Channel Kinetics; Oscillations; Detailed Neuronal Models; Action Potentials; Invertebrate;
Search NeuronDB for information about:  D1; D2; 5-HT1; 5-HT2; 5-HT4; 5-HT3; Dopaminergic Receptor; I Na,p; I Na,t; I N; I A; I K; I h; I K,Ca; I Sodium; I Calcium; I Potassium; I A, slow; Dopamine; Serotonin;
#-- Attractor
# Modeling Interactions Between Electrical Activity and
# Second Messenger Cascades in Aplysia Neuron R15
# Yu et al. 2004, J. Neurophysiol. 91: 2297-2311

# Units: millivolts, milliseconds, nanoamps, microsiemens,
#        nanofarads, millimoles

init V=-38.8468481124207656
init m=0.0196696802720699
init h=0.9963480051353911
init n=0.0504328903497288
init d=0.0000026145195067
init s=0.6584423516466250
init l=0.4382633433755155
init Ca=0.0003
init f=0.9910842262233112
init b=0.0342094859934714
init CaM=0.008
init CaCaM=0.0024
init Ca2CaM=0.00072
init Ca3CaM=0.0000864
init Ca4CaM=0.0000104

#init V=-53.11036793426285
#init m=0.01354547030760796
#init h=0.9999686638933726
#init d=6.126186943402957e-008
#init f=0.9997459538411338
#init s=0.2318420535504265
#init b=2.542904603595237e-006
#init n=0.01934984486453077
#init l=0.8439639705855201
init msyn2=0
init msyn=0
#init Ca=0.0002581366654826358

init cAMP=0.001


#--Stimulus Current

p Astim1=0
p Astim2=0
p Ibias=0
p ts1=0
p te1=0
p ts2=0
p te2=0
p tclamp=200000


p gna=38
p gca=17
p gk=70
p gns=0.2
p gsi=0.65
p gr=0.18
p gl=0.075
p gsyn=1.0

#--Scaling Constants

p Knaca=0.01
p Dnaca=0.01
p Icapmean=7
p Inakmean=5.9
p Dca=0.000150
p Dsicamp=0.00035
#p Dsicamp=0.000842
p Drcamp=0.0004
#p Drcamp=0.0009
p Ksicamp=0.0042
p KsiDA=5.5
p Krcamp=0.001
p Krmod=1.5
p KmodHT=1.2
p KmodCa=1.1
p KmodPDE=0.8
p lamda=0.6
p alpha=0.45

#--Synaptic Input Parameters

p zeta=25
p tau=0.5

#--Reversal Potentials

p Ena=54
p Eca=65
p Ek=-77
p Ens=-22
p El=10.3
p Esyn=-25

#--Michalis-Menten Constants

p Kmsi=0.000025
p Kmcap=0.001
p Kmns=0.000150
p Kpca=0.000350
p Kpna=5.46
p Kpk=0.621
p Kca=0.0005
p KDa=0.2
p KHT=0.006
p Kpde=0.003

#--Reaction Rate Constants

#p C0=0.000
#p D0=0.001
#p VmaxC=0.0005
#p VmaxD=0.002
#p VmaxHT=0.001
#p VmaxCa=0.0009
p Vadc=0.0000006
p Vpde=0.0000024
# from Tarra
param k1f=2300, k1b=2.4, k2f=2300, k2b=2.4, k3f=160000, k3b=405, k4f=160000, k4b=405

p kCh=0.0000968
p kCl=0.075
p kD=0.0000968

#--Cell Properties and Concentrations

p Cm=17.5
p Vol=4
p Bi=0.10125
p Na0=500
p Na=50
p K0=10
p Ca0=10

p DA=0
p HT=0
#--Physical Constants

p Rgas=8314
p Temp=295
p Fc=96500
p ku=100
p kr=0.238
p gamma=0.5
p r=4
p nn=4
p Z=2
p hill=1

#--Time stuff

p y=0
p x=10000
p puff=0.001
p hyper=1000
p cdelay=0
p kclamp=0.1

#--Overall Equation--

Istim1=if (t<ts1 | t>=te1) then (0) else (Astim1)
Istim2=if (t<ts2 | t>=te2) then (0) else (Astim2)
#Vclamp=-kclamp*(V + 75)

#-- Format for most currents

#Tm(V)=1/(Am(V) + Bm(V))

#--Inward Currents--

m'=(1/(1+exp((-10.23-V)/10))-m)/(1/(0.4*(V+6)/(1-exp((-V-6)/4.09)) + 10.75*exp((-28-V)/4.01)))
h'=(1/(1+exp((V+22)/3))-h)/(1/(0.112*exp((-30-V)/10) + 0.23/(exp((9.65-V)/23.9)+1)))



d'=(1/(1+exp((10-V)/3.8))-d)/(1/(0.0063*(V+10.81)/(1-exp((-10.81-V)/5.03)) + 0.01*exp((25-V)/10)))
f'=(1/(1+exp((V+20)/4))-f)/(1/(0.00325*exp((10-V)/7.57) + 0.029/(exp((20.29-V)/5.4) + 1)))



s'=(1/(1+exp((-40-V)/11.5))-s)/(1/(0.0014*(V-54)/(1-exp((-V+54)/12.63)) + 0.00013*exp((-11.32-V)/16.8)))







#--Outward Currents--

n'=(1/(1+exp((3.65-V)/14.46))-n)/(1/(0.0035*(V+17)/(1-exp((-V-17)/3)) + 0.04*exp((-28-V)/10)))




a EyeR=Ir(cAMP,V)

#--Synaptic Current--


#--Pumps and Exchangers--




#--Internal calcium concentration--


CaM'(CaM, CaCaM) = k1b*CaCaM - k1f*Ca*CaM
CaCaM'(CaM, CaCaM, Ca2CaM) = k1f*Ca*CaM - k1b*CaCaM + k2b*Ca2CaM - k2f*Ca*CaCaM 
Ca2CaM'(CaCaM, Ca2CaM, Ca3CaM) = k2f*Ca*CaCaM - k2b*Ca2CaM + k3b*Ca3CaM - k3f*Ca*Ca2CaM
Ca3CaM'(Ca2CaM, Ca3CaM, Ca4CaM) = k3f*Ca*Ca2CaM - k3b*Ca3CaM + k4b*Ca4CaM - k4f*Ca3CaM*Ca
Ca4CaM'(Ca3CaM, Ca4CaM) = k4f*Ca*Ca3CaM - k4b*Ca4CaM
xy=(k1f*Ca*CaM - k1b*CaCaM + k2b*Ca2CaM - k2f*Ca*CaCaM) + 2*(k2f*Ca*CaCaM - k2b*Ca2CaM + k3b*Ca3CaM - k3f*Ca*Ca2CaM) + 3*(k3f*Ca*Ca2CaM - k3b*Ca3CaM + k4b*Ca4CaM - k4f*Ca3CaM*Ca) + 4*(k4f*Ca*Ca3CaM - k4b*Ca4CaM)
Ca'=(Inaca(V,Ca)-Isi(cAMP,s,V,Ca)-Ica(Ca,d,f,V)-Icap(Ca)-0.197*((V-Eca)/(V-Ens))*Ins(b,V,Ca))/(2*Vol*Fc)- xy - nn*Bi*(ku*Ca*(1-Oc)-kr*Oc)

#--Internal cAMP concentration--

Cycpos(Ca34CaM)=Ca34CaM**hill/(Ca34CaM**hill + kCh**hill)
Cycneg(Ca)=kCl**hill/(Ca**hill + kCl**hill)
Cycht=HT/(HT + KHT)

CYCa(Ca34CaM)=Vadc*(alpha + KmodHT*Cycht + KmodCa*Cycpos(Ca34CaM)*Cycneg(Ca34CaM))

PDEa(Ca34CaM)=Vpde*(lamda + KmodPDE*Ca34CaM**hill/(Ca34CaM**hill + kD**hill))


@ TOTAL=80000,dt=0.2
@ METHOD=cvode,BOUND=1e7,TOL=0.00001,ATOL=0.0000001,MAXSTOR=4000000


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