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 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
:
: modified to work with CVode by Carl Gold, 8/10/03
:  Updated by Maria Markaki  12/02/03

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


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


PARAMETER {    :parameters that can be entered when function is called in cell-setup   

	gkabar = 0      (mho/cm2)  :initialized conductance
        vhalfn = -1     (mV)       :activation half-potential (-1), change for pfc, activation at -40
        vhalfl = -56    (mV)       :inactivation half-potential
       	a0n = 0.1       (/ms)      :parameters used
        zetan = -1.8    (1)        :in calculation of
        zetal = 3       (1) 
        gmn   = 0.39    (1)        :and time constants	
        gml   = 1       (1)
	lmin  = 2       (ms)
	nmin  = 0.1     (ms)
	pw    = -1      (1)
	tq    = -40     (mV)
	qq    = 5       (mV)
	q10   = 5                :temperature sensitivity
}


ASSIGNED {    :parameters needed to solve DE
	v               (mV)
        ek              (mV)
	celsius  	(degC)
	ik              (mA/cm2)
        ninf
        linf      
        taul            (ms)
        taun            (ms)
        gka             (mho/cm2)
	ki		(mM)
	ko		(mM)
}


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

: Solve qt once in initial block
LOCAL qt

INITIAL {    :initialize the following parameter using rates()
        qt = q10^((celsius-24)/10(degC))       : temperature adjustment factor
	rates(v)
	n=ninf
	l=linf
}

BREAKPOINT {
	SOLVE states METHOD cnexp
	ek=25 * log(ko/ki)		:Changed, added, 23/04/2010, Nassi
	ik = gkabar*n*l*(v-ek)
}


DERIVATIVE states {     : exact when v held constant; integrates over dt step
        rates(v)          : do this here
        n' = (ninf - n)/taun
        l' = (linf - l)/taul
}



PROCEDURE rates(v (mV)) {		 :callable from hoc
	LOCAL a

        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

        a = alpl(v)
        linf = 1/(1+ a)                  : inactivation variable steady state value
	taul = 0.26(ms/mV)*(v+50)               : inactivation variable time constant (0.26)
	if (taul<lmin) {taul=lmin}       : time constant not allowed to be less than lmin
}


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

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

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

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


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