Functional structure of mitral cell dendritic tuft (Djurisic et al. 2008)

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Accession:136026
The computational modeling component of Djurisic et al. 2008 addressed two primary questions: whether amplification by active currents is necessary to explain the relatively mild attenuation suffered by tuft EPSPs spreading along the primary dendrite to the soma; what accounts for the relatively uniform peak EPSP amplitude throughout the tuft. These simulations show that passive spread from tuft to soma is sufficient to yield the low attenuation of tuft EPSPs, and that random distribution of a biologically plausible number of excitatory synapses throughout the tuft can produce the experimentally observed uniformity of depolarization.
Reference:
1 . Djurisic M, Popovic M, Carnevale N, Zecevic D (2008) Functional structure of the mitral cell dendritic tuft in the rat olfactory bulb. J Neurosci 28:4057-68 [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: Olfactory bulb;
Cell Type(s): Olfactory bulb main mitral GLU cell;
Channel(s): I K; I Sodium;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Dendritic Action Potentials; Active Dendrites; Synaptic Integration; Olfaction;
Implementer(s): Carnevale, Ted [Ted.Carnevale at Yale.edu];
Search NeuronDB for information about:  Olfactory bulb main mitral GLU cell; I K; I Sodium;
COMMENT

kd.mod

Potassium channel, Hodgkin-Huxley style kinetics
Kinetic rates based on Sah et al. and Hamill et al. (1991)

Use with na.mod

Author: Zach Mainen, Salk Institute, 1994, zach@salk.edu
	
ENDCOMMENT

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

NEURON {
	SUFFIX kd
	USEION k READ ek WRITE ik
	RANGE n, gk, gbar
	GLOBAL ninf, ntau, ik
	GLOBAL Ra, Rb, tha, qa
	GLOBAL q10, temp, tadj, vmin, vmax
}

UNITS {
	(mA) = (milliamp)
	(mV) = (millivolt)
	(pS) = (picosiemens)
	(um) = (micron)
} 

PARAMETER {
	gbar = 41.8448   	(pS/um2)	: 0.03 mho/cm2
	v 		(mV)
								
	tha  = 1.00073	(mV)		: v 1/2 for inf
	qa   = 12.4455	(mV)		: inf slope		
	
	Ra   = 0.951283	(/ms)		: max act rate
	Rb   = 0.0125431	(/ms)		: max deact rate	

	dt		(ms)
	celsius		(degC)
	temp = 16	(degC)		: original temp 	
	q10  = 2.3			: temperature sensitivity

	vmin = -120	(mV)
	vmax = 100	(mV)
} 


ASSIGNED {
	a		(/ms)
	b		(/ms)
	ik 		(mA/cm2)
	gk		(pS/um2)
	ek		(mV)
	ninf
	ntau (ms)	
	tadj
}
 

STATE { n }

INITIAL { 
	trates(v)
	n = ninf
}

BREAKPOINT {
        SOLVE states METHOD cnexp
	gk = gbar*n*n*n*n
	ik = (1e-4) * gk * (v - ek)
} 

LOCAL nexp

DERIVATIVE states {   :Computes state variable n 
        trates(v)      :             at the current v and dt.
	n' = (ninf - n)/ntau
}

PROCEDURE trates(v) {  :Computes rate and other constants at current v.
                      :Call once from HOC to initialize inf at resting v.
        TABLE ninf, ntau
	DEPEND celsius, temp, Ra, Rb, tha, qa
	
	FROM vmin TO vmax WITH 199

	rates(v): not consistently executed from here if usetable_hh == 1

}


PROCEDURE rates(v) {  :Computes rate and other constants at current v.
                      :Call once from HOC to initialize inf at resting v.

        a = Ra * (v - tha) / (1 - exp(-(v - tha)/qa))
        b = -Rb * (v - tha) / (1 - exp((v - tha)/qa))
        ntau = 1/(a+b)
	ninf = a*ntau
}


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