CN pyramidal fusiform cell (Kanold, Manis 2001)

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Accession:37856
Pyramidal cells in the dorsal cochlear nucleus (DCN) show three characteristic discharge patterns in response tones: pauser, buildup, and regular firing. Experimental evidence suggests that a rapidly inactivating K+ current (I(KIF)) plays a critical role in generating these discharge patterns. To explore the role of I(KIF), we used a computational model based on the biophysical data. The model replicated the dependence of the discharge pattern on the magnitude and duration of hyperpolarizing prepulses, and I(KIF) was necessary to convey this dependence. Experimentally, half-inactivation voltage and kinetics of I(KIF) show wide variability. Varying these parameters in the model ... suggests that pyramidal cells can adjust their sensitivity to different temporal patterns of inhibition and excitation by modulating the kinetics of I(KIF). Overall, I(KIF) is a critical conductance controlling the excitability of DCN pyramidal cells. (See readme.txt and paper for details). Any questions regarding these implementations should be directed to: pmanis@med.unc.edu 2 April 2004 Paul B Manis, Ph.D.
References:
1 . Kanold PO, Manis PB (2001) A physiologically based model of discharge pattern regulation by transient K+ currents in cochlear nucleus pyramidal cells. J Neurophysiol 85:523-38 [PubMed]
2 . Kanold PO, Manis PB (1999) Transient potassium currents regulate the discharge patterns of dorsal cochlear nucleus pyramidal cells. J Neurosci 19:2195-208 [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:
Cell Type(s): Cochlear nucleus pyramidal/fusiform GLU cell;
Channel(s): I K; I h; I Sodium; I Potassium;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Activity Patterns; Temporal Pattern Generation; Synaptic Integration;
Implementer(s): Manis, Paul B [PManis at med.unc.edu];
Search NeuronDB for information about:  Cochlear nucleus pyramidal/fusiform GLU cell; I K; I h; I Sodium; I Potassium;
COMMENT
alpha function synapse implemented as continuously integrated
kinetic scheme a la Srinivasan and Chiel (Neural Computation) so that
one can give many stimuli which summate.

Onset times are placed in the vector onset[SIZE]
Conductance located in state variable G
The amplitude of each individual alpha function is given by stim,
stim * t * exp(-t/tau).
The last onset time should be a very large number so stim stops getting
added to state A
ENDCOMMENT

DEFINE SIZE 100

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


NEURON {
	POINT_PROCESS KSyn100
	RANGE tau, stim, e, i,onset
	NONSPECIFIC_CURRENT i
}

UNITS {
	(nA) = (nanoamp)
	(mV) = (millivolt)
	(umho) = (micromho)
}

PARAMETER {
	tau = 0.1 (ms)
	stim = 0.05 (umho)
	e=0	(mV)
	v	(mV)	
}

ASSIGNED {
	index
	i (nA)
	bath (umho)
	k (/ms)
	onset[SIZE] (ms)
}

STATE {
	A (umho)
	G (umho)
}

INITIAL {
	k = 1/tau
	A = 0
	G = 0
	index=0
}

? current
BREAKPOINT {
	SOLVE conductance
	i = G*(v - e)
}

: at each onset time a fixed quantity of material is added to state A
: this material moves through G with the form of an alpha function

PROCEDURE conductance() { 
	LOCAL x
	while(index < SIZE && t>onset[index]) {
		index=index+1
		A = A + stim
	}
	SOLVE state METHOD sparse
	
	VERBATIM
	return 0;
	ENDVERBATIM
}

? kinetics
KINETIC state {
	~ A <-> G	(k, 0)
	~ G <-> bath	(k, 0)
}




























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