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 L-type calcium channel with high threshold for activation
: used in somatic and dendritic regions 
: 
: After Borg 


NEURON {
	SUFFIX cal
	USEION ca READ cai, eca WRITE ica
        RANGE gcalbar, ica, po
	GLOBAL inf, s_inf, tau_m
}

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


PARAMETER {     
  	ki     = 0.025  (mM)            : middle point of inactivation fct
	gcalbar = 0   (mho/cm2)  	: initialized conductance
 	taumin  = 180    (ms)           : minimal value of the time cst
        vhalf = -1 (mV)       		:half potential for activation 
	zeta=-4.6
	t0=1.5(ms)
	b = 0.01	(mM) 
        ba = 0.01	(mM)
	bo = 8
}


ASSIGNED {      : parameters needed to solve DE
        v               (mV)
 	celsius         (degC)
	cai             (mM)      : initial internal Ca++ concentration
	ica             (mA/cm2)
	eca             (mV)
:	ical             (mA/cm2)
	po
        inf
	s_inf
	tau_m           (ms)
}

STATE {	
	m 
	s 
} 


INITIAL {
	rates(v,cai)
	m = inf    : initial activation parameter value
	s = s_inf
}

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

BREAKPOINT {
	SOLVE states METHOD cnexp
	po = m*m*h2(cai)
	ica = gcalbar*(po+s*s*bo)*(v-eca)
}


DERIVATIVE states {
	rates(v,cai)
	m' = (inf-m)/t0
	s' = (s_inf-s)/tau_m
}



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

PROCEDURE rates(v(mV), cai(mM)) {LOCAL a, alpha2
		a = alp(v)
		inf = 1/(1+a)
		alpha2 = (cai/b)^2
		s_inf = alpha2 / (alpha2 + 1)
		tau_m = taumin+ 1(ms)*1(mM)/(cai+ba)
}


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