Dentate Gyrus Feed-forward inhibition (Ferrante et al. 2009)

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Accession:124291
In this paper, the model was used to show how that FFI can change a steeply sigmoidal input-output (I/O) curve into a double-sigmoid typical of buffer systems.
Reference:
1 . Ferrante M, Migliore M, Ascoli GA (2009) Feed-forward inhibition as a buffer of the neuronal input-output relation. Proc Natl Acad Sci U S A 106:18004-9 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Realistic Network; Neuron or other electrically excitable cell;
Brain Region(s)/Organism: Dentate gyrus;
Cell Type(s): Dentate gyrus granule GLU cell; Dentate gyrus MOPP cell;
Channel(s): I Na,t; I A; I K;
Gap Junctions:
Receptor(s): GabaA; AMPA; NMDA;
Gene(s):
Transmitter(s): Gaba; Glutamate;
Simulation Environment: NEURON;
Model Concept(s): Action Potential Initiation; Activity Patterns; Ion Channel Kinetics; Synchronization; Spatio-temporal Activity Patterns; Action Potentials; Noise Sensitivity;
Implementer(s): Migliore, Michele [Michele.Migliore at Yale.edu]; Ferrante, Michele [mferr133 at bu.edu]; Ascoli, Giorgio A [ascoli at gmu.edu];
Search NeuronDB for information about:  Dentate gyrus granule GLU cell; GabaA; AMPA; NMDA; I Na,t; I A; I K; Gaba; Glutamate;
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FFI
Granule_Fig_1B_right
fna.mod
ichan2.mod *
kdr.mod
nmdanetGR.mod
FIG_1B_right.hoc
fixnseg.hoc *
n500-axon.hoc
                            
TITLE simple NMDA receptors

: Modified from the original AMPA.mod, M.Migliore Jan 2003
: nmdafactor of 2.65 gives a peak conductance of 1nS in 0Mg

COMMENT
-----------------------------------------------------------------------------

	Simple model for glutamate AMPA receptors
	=========================================

  - FIRST-ORDER KINETICS, FIT TO WHOLE-CELL RECORDINGS

    Whole-cell recorded postsynaptic currents mediated by AMPA/Kainate
    receptors (Xiang et al., J. Neurophysiol. 71: 2552-2556, 1994) were used
    to estimate the parameters of the present model; the fit was performed
    using a simplex algorithm (see Destexhe et al., J. Computational Neurosci.
    1: 195-230, 1994).

  - SHORT PULSES OF TRANSMITTER (0.3 ms, 0.5 mM)

    The simplified model was obtained from a detailed synaptic model that 
    included the release of transmitter in adjacent terminals, its lateral 
    diffusion and uptake, and its binding on postsynaptic receptors (Destexhe
    and Sejnowski, 1995).  Short pulses of transmitter with first-order
    kinetics were found to be the best fast alternative to represent the more
    detailed models.

  - ANALYTIC EXPRESSION

    The first-order model can be solved analytically, leading to a very fast
    mechanism for simulating synapses, since no differential equation must be
    solved (see references below).



References

   Destexhe, A., Mainen, Z.F. and Sejnowski, T.J.  An efficient method for
   computing synaptic conductances based on a kinetic model of receptor binding
   Neural Computation 6: 10-14, 1994.  

   Destexhe, A., Mainen, Z.F. and Sejnowski, T.J. Synthesis of models for
   excitable membranes, synaptic transmission and neuromodulation using a 
   common kinetic formalism, Journal of Computational Neuroscience 1: 
   195-230, 1994.


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ENDCOMMENT



NEURON {
	POINT_PROCESS nmdanet
	RANGE R, g, mg, Alpha, Beta, nmdafactor
	NONSPECIFIC_CURRENT i
	GLOBAL Cdur, Erev, Rinf, Rtau
}
UNITS {
	(nA) = (nanoamp)
	(mV) = (millivolt)
	(umho) = (micromho)
	(mM) = (milli/liter)
}

PARAMETER {

	Cdur	= 1		(ms)	: transmitter duration (rising phase)
	Alpha	= 0.1		(/ms)	: forward (binding) rate
	Beta	= 0.5		(/ms)	: backward (unbinding) rate
:	Alpha	= 0.072		(/ms)	: forward (binding) rate
:	Beta	= 0.0066		(/ms)	: backward (unbinding) rate
	Erev	= 0	(mV)		: reversal potential
	mg	= 1    (mM)		: external magnesium concentration
	nmdafactor=2.65
}


ASSIGNED {
	v		(mV)		: postsynaptic voltage
	i 		(nA)		: current = g*(v - Erev)
	g 		(umho)		: conductance
	Rinf				: steady state channels open
	Rtau		(ms)		: time constant of channel binding
	synon
}

STATE {Ron Roff}

INITIAL {
	Rinf = Alpha / (Alpha + Beta)
	Rtau = 1 / (Alpha + Beta)
	synon = 0
}

BREAKPOINT {
	SOLVE release METHOD cnexp
	g = nmdafactor*mgblock(v)*(Ron + Roff)*1(umho)
	i = g*(v - Erev)		
}

DERIVATIVE release {
	Ron' = (synon*Rinf - Ron)/Rtau
	Roff' = -Beta*Roff
}

: following supports both saturation from single input and
: summation from multiple inputs
: if spike occurs during CDur then new off time is t + CDur
: ie. transmitter concatenates but does not summate
: Note: automatic initialization of all reference args to 0 except first


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, on, nspike, r0, t0 (ms)) {
	: flag is an implicit argument of NET_RECEIVE and  normally 0
        if (flag == 0) { : a spike, so turn on if not already in a Cdur pulse
		nspike = nspike + 1
		if (!on) {
			r0 = r0*exp(-Beta*(t - t0))
			t0 = t
			on = 1
			synon = synon + weight
			state_discontinuity(Ron, Ron + r0)
			state_discontinuity(Roff, Roff - r0)
		}
		: come again in Cdur with flag = current value of nspike
		net_send(Cdur, nspike)
        }
	if (flag == nspike) { : if this associated with last spike then turn off
		r0 = weight*Rinf + (r0 - weight*Rinf)*exp(-(t - t0)/Rtau)
		t0 = t
		synon = synon - weight
		state_discontinuity(Ron, Ron - r0)
		state_discontinuity(Roff, Roff + r0)
		on = 0
	}
}


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