Drosophila 3rd instar larval aCC motoneuron (Gunay et al. 2015)

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Accession:152028
Single compartmental, ball-and-stick models implemented in XPP and full morphological model in Neuron. Paper has been submitted and correlates anatomical properties with electrophysiological recordings from these hard-to-access neurons. For instance we make predictions about location of the spike initiation zone, channel distributions, and synaptic input parameters.
Reference:
1 . G√ľnay C, Sieling FH, Dharmar L, Lin WH, Wolfram V, Marley R, Baines RA, Prinz AA (2015) Distal spike initiation zone location estimation by morphological simulation of ionic current filtering demonstrated in a novel model of an identified Drosophila motoneuron. PLoS Comput Biol 11:e1004189 [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: Drosophila;
Cell Type(s):
Channel(s): I Na,p; I Na,t; I A; I K;
Gap Junctions:
Receptor(s): Cholinergic Receptors;
Gene(s):
Transmitter(s):
Simulation Environment: NEURON; XPP; MATLAB;
Model Concept(s):
Implementer(s): Gunay, Cengiz [cgunay at emory.edu]; Sieling, Fred [fred.sieling at gmail.com]; Prinz, Astrid [astrid.prinz at emory.edu];
Search NeuronDB for information about:  Cholinergic Receptors; I Na,p; I Na,t; I A; I K;
" ball and stick model w 2 comps
" copied from model_I_long_range_better_offset.ode
" Na params close enough to accept this as wildtype cocktail model.
" Can change only 2 out of 3 passive parameters. The last one is dependent to preserve total input resistance.
#
# conductances in nS, resistances in GOhm
# currents in pA  
# Voltages in mV  
# time in ms  
# capacitances in pF  

# Larger soma capacitance, but still low leak
# 3-steps: 16, 36, 56
# Params: gaxon=1.8, NaP=0.1, NaT=350, gKs=1, gaKs=550, Cm=15, Ca=10, gL=0.1, gaL=3, eleak=-55, ealeak=-59

# principles:
# - good for spike height => gaxon, Cm = (3, 20); (1.6, 15)  
# - gaKs > gNaT makes longer delay
# - lowering gaL increases first spike voltage offset
# - high gaKs makes spike asymmetric with slow depolarization
# - lowering Cm increases spike height
# - decreasing gaxon makes spikes shorter and more asymmetric, but requires more current to fire
# - increasing zi increases offset slightly

# firing rate rules:
# - increasing gl decreases galeak and therefore increases f
# - increasing gaxon increases f
# - increasing zi increases f
# - reducing Ca increases f!

# Params: gaxon=1, NaP=0.14, NaT=350, gKs=1, gaKs=550, Cm=15, Ca=10, gL=0.1, gaL=dep(zi), zi=1.6, eleak=-60, ealeak=-60
# pros: nice spike height, goes up to >-10mV
# cons: threshold @ -50mV, spikes a bit too short

# Params: gaxon=1.6, NaP=0.05, NaT=450, gKs=1, gaKs=500, Cm=15, Ca=10, gL=0.1, gaL=dep(zi), zi=1.6, eleak=-60, ealeak=-60
# pros: nice spike height, goes up to >-10mV, threshold @ -40mV
# cons: initial rate too high, spike shape not nice, too small

# Params: gaxon=1.6, NaP=0.08, NaT=260, gKs=1, gaKs=1000, Cm=15, Ca=10, gL=0.1, gaL=dep(zi), zi=1.6, eleak=-60, ealeak=-60
# pros: nice spike height, asymmetric spike shape, initial rate low
# cons: threshold @ -45mV, offset a bit too small

# Params: NaP=0.08, NaT=300, gKs=1, gaKs=1000, Cm=15, Ca=10, gaxon=1.6, gL=0.1, gaL=dep(zi), zi=1.1, eleak=-60, ealeak=-60
# pros: nice spike height, asymmetric spike shape, initial rate low, threshold @ -40mV
# cons: starts firing at 14 pA, must compare f-I curve to recordings

# TODO: make mlab figure and attach to bif.lyx
  
#dV/dt=-1/c*(gKs*mKs^4*(V-EK) + gKf*mKf^4*(fh*hKf+(1-fh)*hKf2)*(V-EK) + gNa*mNa^3*hNa*(V-ENa) + gleak*(V-Eleak)-I)  

# soma voltage
dVm/dt=-1/Cm*(IksVm+IkfVm+gleak*(Vm-Eleak)-I+gaxon*(Vm-Va))

# axon compartment voltage
dVa/dt=-1/Ca*(IksVa+IkfVa+Ina+Inap+galeak*(Va-Ealeak)+gaxon*(Va-Vm))
  
#slow K  
# orig = 5.1
par gKs=1 gaKs=700
minfKs(V) = 1/(1+exp((V+12.85)/(-19.91)))  
mtauKs(V) = 2.03 + 1.96 /(1+exp((V-29.83)/3.32))  
dmKsVm/dt=(minfKs(Vm)-mKsVm)/mtauKs(Vm)  
dmKsVa/dt=(minfKs(Va)-mKsVa)/mtauKs(Va)  
IksVm=gKs*mKsVm^4*(Vm-EK)  
IksVa=gaKs*mKsVa^4*(Va-EK)  
aux IksVm=IksVm
aux IksVa=IksVa

#fast K with 2 inactivation time constants
dmKfVm/dt=(minfKf(Vm)-mKfVm)/mtauKf(Vm)  
dhKfVm/dt=(hinfK(Vm)-hKfVm)/htauK(Vm)  
dhKf2Vm/dt=(hinfK2(Vm)-hKf2Vm)/116  
IkfVm=gKf*mKfVm^4*(fh*hKfVm + (1-fh)*hKf2Vm)*(Vm-EK)  
dmKfVa/dt=(minfKf(Va)-mKfVa)/mtauKf(Va)  
dhKfVa/dt=(hinfK(Va)-hKfVa)/htauK(Va)  
dhKf2Va/dt=(hinfK2(Va)-hKf2Va)/116  
IkfVa=gaKf*mKfVa^4*(fh*hKfVa + (1-fh)*hKf2Va)*(Va-EK)  
minfKf(V) = 1/(1+exp((V+17.55)/(-7.27)))  
mtauKf(V) = 1.94+2.66/(1+exp((V-8.12)/7.96))  
hinfK(V) = 1/(1+exp((V+45)/6))  
htauK(V) = 1.79+515.8/(1+exp((V+147.4)/(28.66)))  
# mistake; should be hinfK == hinfK2
hinfK2(V) = 1/(1+exp((V+44.2)/1.5))
aux IkfVm=IkfVm
aux IkfVa=IkfVa
  
#na  
# from O'Dowd and Aldrich (1988)
dmNa/dt=(minfNa(Va)-mNa)/mtauNa(Va)
dhNa/dt=(hinfNa(Va)-hNa)/htauNa(Va)
Ina=gNa*mNa^3*hNa*(Va-ENa)
# gNa reported as 500 pS/pF, multiply with C=20 pF
par gNa=180
minfNa(V) = 1/(1+exp((V+29.13)/(-8.922)))
mtauNa(V) = 0.1270 + 3.434/(1+exp((V+45.35)/(5.98)))
hinfNa(V) = 1/(1+exp((V+47)/5))
htauNa(V) = 0.36 + exp(-(V+20.65)/(10.47))
aux Ina=Ina

# NaP from DmNav10 of WHL oocyte #1
dmNaP/dt=(minfNaP(Va)-mNaP)/mtauNaP(Va)
Inap=(gNaP+modgNaP)*mNaP*(Va-ENa)
par gNaP=.01
minfNap(V) = 1/(1+exp((V+48.77)/(-3.68)))
mtauNap(V) = 1
aux Inap=Inap

global 1 t {I=Ihold}    
global 1 t-10 {I=Ipulse}  
global 1 t-510 {I=Ihold}  

# initial conditions for settled at I=-6.5
# easiest way is to get this is to save "info" from File menu 
# after running for a long while and then doing a "run last"
init VM=-68.81670299025546 VA=-64.34801596094069 MKSVM=0.05673345401938218 MKSVA=0.07000969210752514 MKFVM=0.0008650853390965969 HKFVM=0.9814660312384692 HKF2VM=0.9839995279862832 MKFVA=0.001598416867905559 HKFVA=0.961752460873017 HKF2VA=0.9900602079074428 MNA=0.01894063272630685 HNA=0.9695223296922046 MNAP=0.01429909346846636

@ total=600,bounds=10000000000,meth=euler,dt=.001, nout=100, maxstor=10000000  

# window ranges
@ xlo=0, xhi=600, ylo=-65, yhi=0

# do a I range from -9 to +51 with 7 steps

# do a I range from 5 to +45 with 2 steps

par Cm=10 Ca=1.8 Ipulse=-6.5

# conserve total input resistance
par zi=2.1

# connection strength
par gaxon=1.3 gleak=0.05

# make some parameters dependent to preserve zi
gad=1/zi-gleak
galeak=1/(1/gad-1/gaxon)

par eleak=-55 ealeak=-55 Ihold=-6.5 

# unneeded pars at the end
par gKf=1 gaKf=200
par ENa=45 EK=-80  I=0 fh=.95 modNaAct=0 modNaInact=0 modgNaP=0

done 

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