Pyramidal neuron conductances state and STDP (Delgado et al. 2010)

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Accession:144482
Neocortical neurons in vivo process each of their individual inputs in the context of ongoing synaptic background activity, produced by the thousands of presynaptic partners a typical neuron has. That background activity affects multiple aspects of neuronal and network function. However, its effect on the induction of spike-timing dependent plasticity (STDP) is not clear. Using the present biophysically-detailed computational model, it is not only able to replicate the conductance-dependent shunting of dendritic potentials (Delgado et al,2010), but show that synaptic background can truncate calcium dynamics within dendritic spines, in a way that affects potentiation more strongly than depression. This program uses a simplified layer 2/3 pyramidal neuron constructed in NEURON. It was similar to the model of Traub et al., J Neurophysiol. (2003), and consisted of a soma, an apical shaft, distal dendrites, five basal dendrites, an axon, and a single spine. The spine’s location was variable along the apical shaft (initial 50 μm) and apical. The axon contained an axon hillock region, an initial segment, segments with myelin, and nodes of Ranvier, in order to have realistic action potential generation. For more information about the model see supplemental material, Delgado et al 2010.
Reference:
1 . Delgado JY, Gómez-González JF, Desai NS (2010) Pyramidal neuron conductance state gates spike-timing-dependent plasticity. J Neurosci 30:15713-25 [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: Auditory cortex;
Cell Type(s): Neocortex L2/3 pyramidal GLU cell;
Channel(s): I Na,p; I Sodium; I Calcium; I Potassium; I_AHP;
Gap Junctions:
Receptor(s): AMPA; NMDA;
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Action Potentials; STDP; Calcium dynamics; Conductance distributions; Audition;
Implementer(s): Gomez-Gonzalez, JF [jfcgomez at ull.edu.es]; Delgado JY, [jyamir at ucla.edu];
Search NeuronDB for information about:  Neocortex L2/3 pyramidal GLU cell; AMPA; NMDA; I Na,p; I Sodium; I Calcium; I Potassium; I_AHP;
TITLE minimal model of NMDA receptors

: PRETTY MUCH AS IN MATHILDE'S VERSION


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

NEURON {
	SUFFIX NMDAKIT
	NONSPECIFIC_CURRENT i
	USEION ca READ cai WRITE ica
	RANGE onset,period, nbre, tau0, tau1, e, B, cao, gmax, g
        GLOBAL Erev, mg, temp, F, R
}
UNITS {
        (mA) = (milliamp)
        (mV) = (millivolt)
        (S) = (siemens)
        (mM) = (milli/liter)
        (celsius) = (degC)
	
}

PARAMETER {
	onset = 100  (ms)
	period = 0 (ms)		: 50
	nbre=20
	tau0 = 2.0 (ms)
	tau1 = 26.0 (ms)

	cao = 2.5	(mM)		: Ca concentration outside the cell
	cai		(mM)		: Ca concentration inside
    Erev    = 0     (mV)            : reversal potential
    gmax            (S/cm2)         : max conductance (100 pS single syn)
    mg      = 1    (mM)             : external magnesium concentration
	Px=4.6925	(cm3 mV/coulomb)	:determined empirically such as 10% of the current is Ca2+ current at -40mV
	F = 96.49 (kilocoulomb)
	R = 8.314 (joule/degC)
	temp = 30		(degC) : (original value = 37)
}

ASSIGNED {
	  ica             (mA/cm2)        : calcium current
        v               (mV)            : postsynaptic voltage
        i               (mA/cm2)        : potassium and sodium current = g*(v - Erev)
        g               (S/cm2)         : conductance of ca
        B                               : magnesium block
}

LOCAL   a[2]
LOCAL   tpeak
LOCAL   adjust
LOCAL   amp

BREAKPOINT {
      B = mgblock(v)          : B is the block by magnesium at this voltage
	g = cond(t,onset)
	if (nbre>1) {
	  FROM j=1 TO (nbre-1) {
	    g=g+cond(t,onset+j*period)
	  }
	}
	g=g*B
        ica = (0.001) * g * (0.051(cm3/coulomb)*v+Px)   *   (4.0*v*F*F / (R * (temp+273) ))   *   (-cao*exptable(-2*v*F/(R* (temp+273) ))  +  cai)  /  (1.0 - exptable(-2.0*v*F/(R* (temp+273) ))) 
	  i = g*(v - Erev) - ica
}

FUNCTION myexp(x) {
	if (x < -100) {
	myexp = 0
	}else{
	myexp = exp(x)
	}
}

FUNCTION cond(x (ms), onset1 (ms)) (S/cm2) {
	tpeak=tau0*tau1*log(tau0/tau1)/(tau0-tau1)
	adjust=1/((1-myexp(-tpeak/tau0))-(1-myexp(-tpeak/tau1)))
	amp=adjust*gmax
	if (x < onset1) {
		cond = 0
	}else{
		a[0]=1-myexp(-(x-onset1)/tau0)
		a[1]=1-myexp(-(x-onset1)/tau1)
		cond = amp*(a[0]-a[1])
	}
}


FUNCTION exptable(x) { 
        TABLE  FROM -10 TO 10 WITH 2000

        if ((x > -10) && (x < 10)) {
                exptable = exp(x)
        } else {
                exptable = 0.
        }
}

FUNCTION mgblock(v(mV)) {
        TABLE 
        DEPEND mg
        FROM -140 TO 80 WITH 1000

        : from Jahr & Stevens

        mgblock = 1 / (1 + exp(0.062 (/mV) * -v) * (mg / 3.57 (mM)))
}


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