L5 PFC microcircuit used to study persistent activity (Papoutsi et al. 2014, 2013)

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Accession:155057
Using a heavily constrained biophysical model of a L5 PFC microcircuit we investigate the mechanisms that underlie persistent activity emergence (ON) and termination (OFF) and search for the minimum network size required for expressing these states within physiological regimes.
References:
1 . Papoutsi A, Sidiropoulou K, Cutsuridis V, Poirazi P (2013) Induction and modulation of persistent activity in a layer V PFC microcircuit model. Front Neural Circuits 7:161 [PubMed]
2 . Papoutsi A, Sidiropoulou K, Poirazi P (2014) Dendritic nonlinearities reduce network size requirements and mediate ON and OFF states of persistent activity in a PFC microcircuit model. PLoS Comput Biol 10:e1003764 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Dendrite; Connectionist Network;
Brain Region(s)/Organism: Neocortex;
Cell Type(s): Neocortex L5/6 pyramidal GLU cell;
Channel(s): I Na,p; I Na,t; I L high threshold; I A; I CAN; I Potassium; I R; I_AHP;
Gap Junctions:
Receptor(s): GabaA; GabaB; AMPA; NMDA;
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Active Dendrites; Working memory;
Implementer(s): Papoutsi, Athanasia [athpapoutsi at gmail.com];
Search NeuronDB for information about:  Neocortex L5/6 pyramidal GLU cell; GabaA; GabaB; AMPA; NMDA; I Na,p; I Na,t; I L high threshold; I A; I CAN; I Potassium; I R; I_AHP;
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L5microcircuit
mechanism
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TITLE N-type calcium channel 
: used in somatic and dendritic regions 
: After Borg 


NEURON {
	SUFFIX can
	USEION ca READ cai, eca WRITE ica 
        RANGE gcabar, ica, po
	GLOBAL hinf, minf, s_inf
}

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 
	gcabar = 0   (mho/cm2)  : initialized conductance
  	ki     = 0.025  (mM)            :test middle point of inactivation fct
	zetam = -3.4
	zetah = 2
	vhalfm =-21 (mV)
	vhalfh =-40 (mV)
	tm0=1.5(ms)
	th0=75(ms)
	taumin  = 2    (ms)            : minimal value of the time cst
}



ASSIGNED {     : parameters needed to solve DE
	v            (mV)
	celsius      (degC)
	ica          (mA/cm2)
	po
	cai          (mM)       :5e-5 initial internal Ca++ concentration
	eca             (mV)
        minf
        hinf
	s_inf
}


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



STATE {	
	m 
	h 
	s
}  

INITIAL {
	rates(v,cai)
        m = minf
        h = hinf
	s = s_inf
}

BREAKPOINT {
	SOLVE states METHOD cnexp
	po = m*m*h
 	ica = gcabar *po*h2(cai) * (v - eca)

}


FUNCTION ghk(v(mV), ci(mM), co(mM)) (.001 coul/cm3) {
	LOCAL z, eci, eco
	z = (1e-3)*2*FARADAY*v/(R*(celsius+273.15))
	eco = co*efun(z)
	eci = ci*efun(-z)
	:high cao charge moves inward
	:negative potential charge moves inward
	ghk = (.001)*2*FARADAY*(eci - eco)
}

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

DERIVATIVE states {
	rates(v,cai)
	m' = (minf -m)/tm0
	h'=  (hinf - h)/th0
	s' = (s_inf-s)/taumin
}



PROCEDURE rates(v (mV), cai(mM)) { 
        LOCAL a, b, alpha2
        
	a = alpm(v)
	minf = 1/(1+a)
        
        b = alph(v)
	hinf = 1/(1+b)
	alpha2 = (ki/cai)^2
	s_inf = alpha2 / (alpha2 + 1)
}




FUNCTION alpm(v(mV)) {
UNITSOFF
  alpm = exp(1.e-3*zetam*(v-vhalfm)*9.648e4/(8.315*(273.16+celsius))) 
UNITSON
}

FUNCTION alph(v(mV)) {
UNITSOFF
  alph = exp(1.e-3*zetah*(v-vhalfh)*9.648e4/(8.315*(273.16+celsius))) 
UNITSON
}


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