CA1 pyramidal neuron: depolarization block (Bianchi et al. 2012)

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Accession:143719
NEURON files from the paper: On the mechanisms underlying the depolarization block in the spiking dynamics of CA1 pyramidal neurons by D.Bianchi, A. Marasco, A.Limongiello, C.Marchetti, H.Marie,B.Tirozzi, M.Migliore (2012). J Comput. Neurosci. In press. DOI: 10.1007/s10827-012-0383-y. Experimental findings shown that under sustained input current of increasing strength neurons eventually stop firing, entering a depolarization block. We analyze the spiking dynamics of CA1 pyramidal neuron models using the same set of ionic currents on both an accurate morphological reconstruction and on its reduction to a single-compartment. The results show the specic ion channel properties and kinetics that are needed to reproduce the experimental findings, and how their interplay can drastically modulate the neuronal dynamics and the input current range leading to depolarization block.
Reference:
1 . Bianchi D, Marasco A, Limongiello A, Marchetti C, Marie H, Tirozzi B, Migliore M (2012) On the mechanisms underlying the depolarization block in the spiking dynamics of CA1 pyramidal neurons. J Comput Neurosci 33:207-25 [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: Hippocampus;
Cell Type(s): Hippocampus CA1 pyramidal cell;
Channel(s): I Na,t; I A; I K; I M; I h; I K,Ca; I_AHP;
Gap Junctions:
Receptor(s): GabaA; AMPA; NMDA;
Gene(s):
Transmitter(s): Gaba; Glutamate;
Simulation Environment: NEURON; Mathematica;
Model Concept(s): Simplified Models; Depolarization block; Bifurcation;
Implementer(s): Bianchi, Daniela [danielabianchi12 -at- gmail.com]; Limongiello, Alessandro [alessandro.limongiello at unina.it];
Search NeuronDB for information about:  Hippocampus CA1 pyramidal cell; GabaA; AMPA; NMDA; I Na,t; I A; I K; I M; I h; I K,Ca; I_AHP; Gaba; Glutamate;
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Ca1_Bianchi
experiment
cad.mod *
cagk.mod *
cal.mod *
calH.mod *
car.mod *
cat.mod *
d3.mod *
h.mod *
kadist.mod *
kaprox.mod *
kca.mod *
kdr.mod *
km.mod *
na3.mod *
na3dend.mod *
na3notrunk.mod *
nap.mod *
nax.mod *
somacar.mod *
cell-setup.hoc
mosinit.hoc
sessio.ses
Simulation.hoc
                            
TITLE Ca L-type channel with high treshold of activation
: inserted in distal dendrites to account for distally
: restricted initiation of Ca++ spikes
: uses channel conductance (not permeability)
: written by Yiota Poirazi, 1/8/00 poirazi@LNC.usc.edu

NEURON {
	SUFFIX calH
	USEION ca READ eca WRITE ica
        RANGE gcalbar, m, h
	RANGE inf, fac, tau
}

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



PARAMETER {          : parameters that can be entered when function is called in cell-setup
        v               (mV)
        celsius = 34	(degC)
	dt              (ms)
        gcalbar = 0     (mho/cm2) : initialized conductance
	eca = 140       (mV)      : Ca++ reversal potential
        }

STATE {	m h }                     : unknown activation and inactivation parameters to be solved in the DEs  

ASSIGNED {
	ica (mA/cm2)
      inf[2]
	tau[2]

        
}


INITIAL {
      m = 0    : initial activation parameter value
	h = 1    : initial inactivation parameter value
	rate(v)
	
}

BREAKPOINT {
	SOLVE state METHOD cnexp
	ica = gcalbar*m*m*m*h*(v - eca)

}



DERIVATIVE state {  
        rate(v)
        m' = (inf[0]-m)/tau[0]
	  h' = (inf[1]-h)/tau[1]

}

PROCEDURE rate(v (mV)) { :callable from hoc
       FROM i=0 TO 1 {
		tau[i] = vartau(v,i)
		inf[i] = varss(v,i)
	}

     
	
}


FUNCTION varss(v, i) {
	if (i==0) { 
             varss = 1 / (1 + exp((v+37)/(-1)))  : Ca activation 
	}
	else if (i==1) { 
             varss = 1 / (1 + exp((v+41)/(0.5))) : Ca inactivation 
	}
}

FUNCTION vartau(v, i) {
	if (i==0) {
          vartau = 3.6  : activation variable time constant
         

        }
	else if (i==1) {
:           vartau = 25   : inactivation variable time constant
           vartau = 29   : inactivation variable time constant
        }
}	


















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