Afferent Integration in the NAcb MSP Cell (Wolf et al. 2005)

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Accession:112834
"We describe a computational model of the principal cell in the nucleus accumbens (NAcb), the medium spiny projection (MSP) neuron. The model neuron, constructed in NEURON, includes all of the known ionic currents in these cells and receives synaptic input from simulated spike trains via NMDA, AMPA, and GABAA receptors. ... results suggest that afferent information integration by the NAcb MSP cell may be compromised by pathology in which the NMDA current is altered or modulated, as has been proposed in both schizophrenia and addiction."
Reference:
1 . Wolf JA, Moyer JT, Lazarewicz MT, Contreras D, Benoit-Marand M, O'Donnell P, Finkel LH (2005) NMDA/AMPA ratio impacts state transitions and entrainment to oscillations in a computational model of the nucleus accumbens medium spiny projection neuron. J Neurosci 25:9080-95 [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): Nucleus accumbens spiny projection neuron;
Channel(s): I Na,p; I Na,t; I L high threshold; I N; I T low threshold; I A; I h; I K,Ca; I Krp; I R; I Q;
Gap Junctions:
Receptor(s): GabaA; AMPA; NMDA;
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Oscillations; Schizophrenia; Addiction;
Implementer(s): Wolf, John A. [johnwolf at warpmail.net]; Moyer, Jason [jtmoyer at seas.upenn.edu];
Search NeuronDB for information about:  GabaA; AMPA; NMDA; I Na,p; I Na,t; I L high threshold; I N; I T low threshold; I A; I h; I K,Ca; I Krp; I R; I Q;
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nacb_msp
tau_tables
readme.html
AMPA.mod
bkkca.mod *
cadyn.mod *
caL.mod *
caL13.mod *
caldyn.mod
can.mod *
caq.mod *
car.mod *
cat.mod *
GABA.mod *
kaf.mod *
kas.mod *
kir.mod *
krp.mod *
naf.mod *
nap.mod *
NMDA.mod
skkca.mod *
stim.mod *
_run_me.hoc
all_tau_vecs.hoc *
baseline_values.txt *
basic_procs.hoc
create_mspcells.hoc *
current_clamp.ses *
make_netstims.hoc
mosinit.hoc *
msp_template.hoc
nacb_main.hoc
netstims_template.hoc *
screenshot.jpg
screenshot2.jpg
stimxout_jns_sqwave.dat
synapse_templates.hoc
                            
TITLE Kir potassium current for nucleus accumbens (IRK1 = Kir 2.1 - see Mermelstein)

COMMENT 

Mermelstein PG, Song WJ, Tkatch T, Yan Z, Surmeier DJ (1998) Inwardly
rectifying potassium (IRK) currents are correlated with IRK subunit
expression in rat nucleus accumbens medium spiny neurons. J Neurosci
18:6650-6661.

Uchimura N, Cherubini E, North RA (1989).  Inward rectification
in rat nucleus accumbens neurons. J Neurophysiol 62, 1280-1286.

Kubo Y, Murata Y (2001).  Control of rectification and permeation by two
distinct sites after the second transmembrane region in Kir2.1 K+
channel. J Physiol 531, 645-660.

Hayashi H, Fishman HM (1988). Inward rectifier K+ channel kinetics from
analysis of the complex conductance of aplysia neuronal membrane.
Biophys J 53, 747-757. 

Jason Moyer 2004 jtmoyer@seas.upenn.edu
ENDCOMMENT


UNITS {
        (mA) = (milliamp)
        (mV) = (millivolt)
        (S)  = (siemens)
        (molar) = (1/liter)
        (mM) = (millimolar)
}
 
NEURON {
        SUFFIX kir
        USEION k READ ek WRITE ik
        RANGE  gkbar, ik, mvhalf, mslope, mshift, qfact
}
 
PARAMETER {
	gkbar  = 0.00015 		(S/cm2)	: 

	mvhalf = -52		(mV)	: fit to Hayashi 1988 fig 14; minf = alpha/(alpha+beta)
	mslope = 13		(mV)	: fit to Hayashi 1988 fig 14
	mshift = 30			(mV)	: fit to Kubo 2001 fig 2B left - with ek = -84.3,
						:  mshift can range from 20 to 30 to fit slope of IR
	qfact = 0.5				: match in vitro data
}
 
STATE { m }
 
ASSIGNED {
		ki				(mM)
		ko				(mM)
        v 				(mV)
        ik 				(mA/cm2)
        gk				(S/cm2)
        minf		
        ek				(mV)
   }
 
BREAKPOINT {
        SOLVE state METHOD cnexp
        gk = gkbar * m
        ik = gk * ( v - ek )
}
  
INITIAL {
	rates(v)
	m = minf
}

FUNCTION_TABLE taumkir (v(mV))  (ms)		: Hayashi

DERIVATIVE state { 
        rates(v)
        m' = (minf - m) / ( taumkir(v)/qfact )
}
 
PROCEDURE rates( v(mV) ) {  : Boltzman adjusted to give proper Erev dependency 
	TABLE minf DEPEND mvhalf, mshift, mslope
		FROM -200 TO 200 WITH 201
			minf = 1  /  ( 1 + exp( (v - mvhalf + mshift) / mslope) )
}
 
 

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