CA1 pyramidal neuron: dendritic Ca2+ inhibition (Muellner et al. 2015)

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Accession:206244
In our experimental study, we combined paired patch-clamp recordings and two-photon Ca2+ imaging to quantify inhibition exerted by individual GABAergic contacts on hippocampal pyramidal cell dendrites. We observed that Ca2+ transients from back-propagating action potentials were significantly reduced during simultaneous activation of individual nearby GABAergic synapses. To simulate dendritic Ca2+ inhibition by individual GABAergic synapses, we employed a multi-compartmental CA1 pyramidal cell model with detailed morphology, voltage-gated channel distributions, and calcium dynamics, based with modifications on the model of Poirazi et al., 2003, modelDB accession # 20212.
Reference:
1 . Müllner FE, Wierenga CJ, Bonhoeffer T (2015) Precision of Inhibition: Dendritic Inhibition by Individual GABAergic Synapses on Hippocampal Pyramidal Cells Is Confined in Space and Time. Neuron 87:576-89 [PubMed]
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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: Hippocampus;
Cell Type(s): Hippocampus CA1 pyramidal cell;
Channel(s): I Calcium; I Sodium; I Potassium; I h;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s): Gaba;
Simulation Environment: NEURON;
Model Concept(s): Action Potentials; Dendritic Action Potentials; Active Dendrites; Calcium dynamics;
Implementer(s): Muellner, Fiona E [fiona.muellner at gmail.com];
Search NeuronDB for information about:  Hippocampus CA1 pyramidal cell; I h; I Sodium; I Calcium; I Potassium; Gaba;
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CA1_multi
mechanism
previously used
ampa.mod *
cad.mod
cagk.mod *
cal.mod *
calH.mod *
cat.mod
cldif.mod
d3.mod *
gabaA_Cl.mod
h.mod *
hha_old.mod *
hha2.mod *
kadist.mod *
kaprox.mod *
kca.mod *
km.mod *
nap.mod *
nmda.mod *
                            
TITLE K-A channel from Klee Ficker and Heinemann
: modified by Brannon and Yiota Poirazi (poirazi@LNC.usc.edu) 
: to account for Hoffman et al 1997 distal region kinetics
: used only in locations > 100 microns from the soma


UNITS {
	(mA) = (milliamp)
	(mV) = (millivolt)
}

INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}

PARAMETER {                        :parameters that can be entered when function is called in cell-setup   
        dt (ms)
	v (mV)
        ek = -80                   :K reversal potential  (reset in cell-setup.hoc)
	celsius = 24	(degC)
:	gkabar = 0.008  (mho/cm2)  :suggested conductance value
	gkabar = 0      (mho/cm2)  :initialized conductance
        vhalfn = -1     (mV)       :activation half-potential
        vhalfl = -56    (mV)       :inactivation half-potential
        a0n = 0.1       (/ms)      :parameters used
        zetan = -1.8    (1)        :in calculation of
        zetal = 3       (1)        :steady state values
        gmn   = 0.39    (1)        :and time constants
        gml   = 1       (1)
	lmin  = 2       (mS)
	nmin  = 0.1     (mS)
	pw    = -1      (1)
	tq    = -40
	qq    = 5
	q10   = 5                  :temperature sensitivity
}


NEURON {
	SUFFIX kad
	USEION k READ ek WRITE ik
        RANGE gkabar,gka
        GLOBAL ninf,linf,taul,taun,lmin
}

STATE {       :the unknown parameters to be solved in the DEs 
	n l
}

ASSIGNED {    :parameters needed to solve DE
	ik (mA/cm2)
        ninf
        linf      
        taul
        taun
        gka
}

INITIAL {    :initialize the following parameter using rates()
	rates(v)
	n=ninf
	l=linf
	gka = gkabar*n*l
	ik = gka*(v-ek)	
}

BREAKPOINT {
	SOLVE states
	gka = gkabar*n*l
	ik = gka*(v-ek)
}

FUNCTION alpn(v(mV)) { LOCAL zeta
  zeta = zetan+pw/(1+exp((v-tq)/qq))
  alpn = exp(1.e-3*zeta*(v-vhalfn)*9.648e4/(8.315*(273.16+celsius))) 
}

FUNCTION betn(v(mV)) { LOCAL zeta
  zeta = zetan+pw/(1+exp((v-tq)/qq))
  betn = exp(1.e-3*zeta*gmn*(v-vhalfn)*9.648e4/(8.315*(273.16+celsius))) 
}

FUNCTION alpl(v(mV)) {
  alpl = exp(1.e-3*zetal*(v-vhalfl)*9.648e4/(8.315*(273.16+celsius))) 
}

FUNCTION betl(v(mV)) {
  betl = exp(1.e-3*zetal*gml*(v-vhalfl)*9.648e4/(8.315*(273.16+celsius))) 
}
LOCAL facn,facl
:if state_borgka 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.
PROCEDURE states() {     : exact when v held constant; integrates over dt step
        rates(v)
        n = n + facn*(ninf - n)
        l = l + facl*(linf - l)
        VERBATIM
        return 0;
        ENDVERBATIM
}

PROCEDURE rates(v (mV)) {		 :callable from hoc
        LOCAL a,qt
        qt = q10^((celsius-24)/10)       : temprature adjastment factor
        a = alpn(v)
        ninf = 1/(1 + a)		 : activation variable steady state value
        taun = betn(v)/(qt*a0n*(1+a))	 : activation variable time constant
	if (taun<nmin) {taun=nmin}	 : time constant not allowed to be less than nmin
        facn = (1 - exp(-dt/taun))
        a = alpl(v)
        linf = 1/(1+ a)                  : inactivation variable steady state value
	taul = 0.26*(v+50)               : inactivation variable time constant
	if (taul<lmin) {taul=lmin}       : time constant not allowed to be less than lmin
        facl = (1 - exp(-dt/taul))
}