CA1 pyramidal neuron: synaptically-induced bAP predicts synapse location (Sterratt et al. 2012)

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Accession:144490
This is an adaptation of Poirazi et al.'s (2003) CA1 model that is used to measure BAP-induced voltage and calcium signals in spines after simulated Schaffer collateral synapse stimulation. In the model, the peak calcium concentration is highly correlated with soma-synapse distance under a number of physiologically-realistic suprathreshold stimulation regimes and for a range of dendritic morphologies. There are also simulations demonstrating that peak calcium can be used to set up a synaptic democracy in a homeostatic manner, whereby synapses regulate their synaptic strength on the basis of the difference between peak calcium and a uniform target value.
Reference:
1 . Sterratt DC, Groen MR, Meredith RM, van Ooyen A (2012) Spine calcium transients induced by synaptically-evoked action potentials can predict synapse location and establish synaptic democracy. PLoS Comput Biol 8:e1002545 [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): Hippocampus CA1 pyramidal GLU cell;
Channel(s): I Na,t; I L high threshold; I T low threshold; I A; I K; I M; I Mixed; I R; I_AHP;
Gap Junctions:
Receptor(s): AMPA; NMDA;
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Dendritic Action Potentials; Synaptic Plasticity;
Implementer(s): Sterratt, David ; Groen, Martine R [martine.groen at gmail.com];
Search NeuronDB for information about:  Hippocampus CA1 pyramidal GLU cell; AMPA; NMDA; I Na,t; I L high threshold; I T low threshold; I A; I K; I M; I Mixed; I R; I_AHP;
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bpap
CA1_multi
datastore
pars
plots
poirazi-nmda-car
tests
validation-plots
README.txt
ampa_forti.mod
cacum.mod
cad.mod *
cagk.mod
cal.mod
calH.mod
car.mod
car_mag.mod
cat.mod
d3.mod *
h.mod
hha_old.mod
hha2.mod
kadist.mod
kaprox.mod
kca.mod
km.mod
nap.mod
nmda_andr.mod
somacar.mod
binaverages.m
bpap-cell.hoc
bpap-data.hoc
bpap-dendburst.hoc
bpap-graphics.hoc
bpap-gui.hoc
bpap-gui.ses
bpap-pars.hoc
bpap-record.hoc
bpap-run.hoc
bpap-scaling.hoc
bpap-sims.hoc
bpap-sims-cell1.hoc
bpap-sims-cell2.hoc
bpap-sims-scaling.hoc
bpap-somainj.hoc
bpap-spiketrain.hoc
ca1_mrg_cell1.hoc
ca1_mrg_cell2.hoc
ca1_poirazi.hoc
ChannelBlocker.hoc
CrossingFinder.hoc
epspsizes.hoc
figure-example.R
figures.R
figures-common.R
FileUtils.hoc
FormatFile.hoc
ghk.inc
GraphUtils.hoc
Integrator.hoc
Makefile
mosinit.hoc
NmdaAmpaSpineSynStim.hoc
NmdaAmpaSynStim.hoc
ObjectClass.hoc
plotscalingresults_pergroup1.m
plotscalingresults5.m
PointProcessDistributor.hoc
ReferenceAxis.hoc
removezeros.m
RPlot.hoc
scaling_plots.m
Segment.hoc
SimpleSpine.hoc
Spine.hoc
TreePlot.hoc
TreePlotArray.hoc
triexpsyn.inc
units.inc
utils.hoc
validate-bpap.hoc
VarList.hoc
VCaGraph.hoc
                            
TITLE L-type calcium channel with low threshold for activation
: used in somatic and proximal dendritic regions 
: it calculates I_Ca using channel permeability instead of conductance

UNITS {
	  (mA) = (milliamp)
	  (mV) = (millivolt)
    (molar) = (1/liter)
    (mM) = (millimolar)
    FARADAY = (faraday) (coulomb)
    R = (k-mole) (joule/degC)
}

PARAMETER {		:parameters that can be entered when function is called in cell-setup 
	  v             (mV)
	  celsius = 34	(degC)
	  gcalbar = 0   (mho/cm2)   : initialized conductance
	  ki  = 0.001   (mM)  
	  cai = 5.e-5   (mM)        : initial internal Ca++ concentration
	  cao = 2       (mM)        : initial external Ca++ concentration
    tfa = 5                   : time constant scaling factor
    eca = 140     (mV)        : Ca++ reversal potential
}

NEURON {
	  SUFFIX cal
	  USEION ca READ cai,cao WRITE ica
    RANGE gcalbar, gmax, gcal, minf, taum
}

STATE {	m }                      : unknown parameter to be solved in the DEs 

ASSIGNED {                       : parameters needed to solve DE
	  ica   (mA/cm2)
    gcal  (mho/cm2)
    gmax  (mho/cm2) 
    minf
    taum  (ms)
}

INITIAL {                        : initialize the following parameter using rates()
    rates(v)
    m = minf
	  gcal = gcalbar*m*h2(cai)
}

BREAKPOINT {
	  SOLVE states METHOD cnexp
	  gcal = gcalbar*m*h2(cai) : maximum channel permeability
	  ica = gcal*ghk(v,cai,cao): calcium current induced by this channel
    if (gcal > gmax) {
        gmax = gcal
    }
}

FUNCTION h2(cai(mM)) {
	  h2 = ki/(ki+cai)
}

FUNCTION ghk(v(mV), ci(mM), co(mM)) (mV) {
    LOCAL nu,f
    f = KTF(celsius)/2
    nu = v/f
    ghk=-f*(1. - (ci/co)*exp(nu))*efun(nu)
}

FUNCTION KTF(celsius (degC)) (mV) { : temperature-dependent adjustment factor
    KTF = ((25.(mV)/293.15(degC))*(celsius + 273.15(degC)))
}

FUNCTION efun(z) {
	  if (fabs(z) < 1e-4) {
		    efun = 1 - z/2
	  }else{
		    efun = z/(exp(z) - 1)
	  }
}

FUNCTION alpm(v (mV)) (/ms) {
	  alpm = 0.055(/ms/mV)*(-27.01(mV) - v)/(exp((-27.01(mV)-v)/3.8(mV)) - 1)
}


FUNCTION betm(v (mV)) (/ms) {
    betm =0.94(/ms)*exp((-63.01(mV)-v)/17(mV))
}

:if state_cagk is called from hoc, garbage or segmentation violation will
:result because range variables won't have correct pointer.  This is because
:only BREAKPOINT sets up the correct pointers to range variables.
DERIVATIVE states {     : exact when v held constant; integrates over dt step
    rates(v)
    m' = (minf - m)/taum
}

PROCEDURE rates(v (mV)) { :callable from hoc
    LOCAL a
    TABLE taum, minf FROM -150 TO 150 WITH 300 
    a = alpm(v)
    taum = 1/(tfa*(a+betm(v))) : estimation of activation tau
    minf = a/(a+betm(v))       : estimation of activation steady state value
}

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