MEC layer II stellate cell: Synaptic mechanisms of grid cells (Schmidt-Hieber & Hausser 2013)

 Download zip file   Auto-launch 
Help downloading and running models
Accession:150239
This study investigates the cellular mechanisms of grid field generation in Medial Entorhinal Cortex (MEC) layer II stellate cells.
Reference:
1 . Schmidt-Hieber C, Häusser M (2013) Cellular mechanisms of spatial navigation in the medial entorhinal cortex. Nat Neurosci 16:325-31 [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: Entorhinal cortex;
Cell Type(s): Entorhinal cortex stellate cell;
Channel(s): I Na,t; I A; I K; I CNG;
Gap Junctions:
Receptor(s): GabaA; AMPA; NMDA; Gaba;
Gene(s):
Transmitter(s):
Simulation Environment: NEURON; Python;
Model Concept(s): Oscillations; Synaptic Integration; Attractor Neural Network; Place cell/field; Spatial Navigation; Grid cell;
Implementer(s): Schmidt-Hieber, Christoph [c.schmidt-hieber at ucl.ac.uk];
Search NeuronDB for information about:  GabaA; AMPA; NMDA; Gaba; I Na,t; I A; I K; I CNG;
COMMENT
Combines NEURON'S Exp2Syn mechanism with voltage-dependence of Mg2+ 
block to produce a simple NMDAR conductance.

Original comment:

Two state kinetic scheme synapse described by rise time tau1,
and decay time constant tau2. The normalized peak condunductance is 1.
Decay time MUST be greater than rise time.

The solution of A->G->bath with rate constants 1/tau1 and 1/tau2 is
 A = a*exp(-t/tau1) and
 G = a*tau2/(tau2-tau1)*(-exp(-t/tau1) + exp(-t/tau2))
	where tau1 < tau2

If tau2-tau1 -> 0 then we have a alphasynapse.
and if tau1 -> 0 then we have just single exponential decay.

The factor is evaluated in the
initial block such that an event of weight 1 generates a
peak conductance of 1.

Because the solution is a sum of exponentials, the
coupled equations can be solved as a pair of independent equations
by the more efficient cnexp method.

ENDCOMMENT

NEURON {
	POINT_PROCESS Exp2SynNMDA
	RANGE tau1, tau2, e, i
	NONSPECIFIC_CURRENT i

	RANGE g
}

UNITS {
	(nA) = (nanoamp)
	(mV) = (millivolt)
	(uS) = (microsiemens)
}

PARAMETER {
	tau1=.1 (ms) <1e-9,1e9>
	tau2 = 10 (ms) <1e-9,1e9>
	e=0	(mV)
	mg=1    (mM)		: external magnesium concentration
}

ASSIGNED {
	v (mV)
	i (nA)
	g (uS)
	factor
}

STATE {
	A (uS)
	B (uS)
}

INITIAL {
	LOCAL tp
	if (tau1/tau2 > .9999) {
		tau1 = .9999*tau2
	}
	A = 0
	B = 0
	tp = (tau1*tau2)/(tau2 - tau1) * log(tau2/tau1)
	factor = -exp(-tp/tau1) + exp(-tp/tau2)
	factor = 1/factor
}

BREAKPOINT {
	SOLVE state METHOD cnexp
	g = B - A
	i = g*mgblock(v)*(v - e)
}

DERIVATIVE state {
	A' = -A/tau1
	B' = -B/tau2
}

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)))
}

NET_RECEIVE(weight (uS)) {
	A = A + weight*factor
	B = B + weight*factor
}

Loading data, please wait...