O-LM interneuron model (Lawrence et al. 2006)

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Accession:102288
Exploring the kinetics and distribution of the muscarinic potassium channel, IM, in 2 O-LM interneuron morphologies. Modulation of the ion channel by drugs such as XE991 (antagonist) and retigabine (agonist) are simulated in the models to examine the role of IM in spiking properties.
Reference:
1 . Lawrence JJ, Saraga F, Churchill JF, Statland JM, Travis KE, Skinner FK, McBain CJ (2006) Somatodendritic Kv7/KCNQ/M channels control interspike interval in hippocampal interneurons. J Neurosci 26:12325-38 [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): Hippocampus CA1 interneuron oriens alveus GABA cell;
Channel(s): I L high threshold; I N; I T low threshold; I A; I K; I K,leak; I M; I h; I K,Ca;
Gap Junctions:
Receptor(s): Muscarinic;
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Ion Channel Kinetics; Oscillations; Detailed Neuronal Models; Action Potentials;
Implementer(s):
Search NeuronDB for information about:  Hippocampus CA1 interneuron oriens alveus GABA cell; Muscarinic; I L high threshold; I N; I T low threshold; I A; I K; I K,leak; I M; I h; I K,Ca;
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RichyandStarfish
readme.html
cad.mod *
ICaL.mod *
ICaT.mod *
Ih.mod
IKa.mod *
IKCa.mod *
Ikdrf.mod *
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Ikleakaxon.mod *
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IMminret.mod *
IMmintau.mod *
Ipassaxon.mod *
Ipasssd.mod *
Naaxon.mod *
Nadend.mod *
Nasoma.mod *
SIN.mod *
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Starfishtrunc.hoc
                            
COMMENT

Ih current	 - hyperpolarization-activated nonspecific Na and K channel
		 - contributes to the resting membrane potential
		 - controls the afterhyperpolarization
Reference:

1.	Maccaferri, G. and McBain, C.J. The hyperpolarization-activated current
	(Ih) and its contribution to pacemaker activity in rat CA1 hippocampal
	stratum oriens-alveus interneurons, J. Physiol. 497.1:119-130,
	1996.

		V1/2 = -84.1 mV
		   k = 10.2
		reversal potential = -32.9 +/- 1.1 mV

at -70 mV, currents were fitted by a single exponetial of t = 2.8+/- 0.76 s
at -120 mV, two exponentials were required, t1 = 186.3+/-33.6 ms 
t2 = 1.04+/-0.16 s


2.	Maccaferri, G. et al. Properties of the
	Hyperpoarization-activated current in rat hippocampal CA1 Pyramidal
	cells. J. Neurophysiol. Vol. 69 No. 6:2129-2136, 1993.

		V1/2 = -97.9 mV
		   k = 13.4
		reversal potential = -18.3 mV

3.	Pape, H.C.  Queer current and pacemaker: The
	hyperpolarization-activated cation current in neurons, Annu. Rev. 
	Physiol. 58:299-327, 1996.

		single channel conductance is around 1 pS
		average channel density is below 0.5 um-2
		0.5 pS/um2 = 0.00005 mho/cm2 = 0.05 umho/cm2		
4.	Magee, J.C. Dendritic Hyperpolarization-Activated Currents Modify
	the Integrative Properties of Hippocampal CA1 Pyramidal Neurons, J.
	Neurosci., 18(19):7613-7624, 1998

Deals with Ih in CA1 pyramidal cells.  Finds that conductance density
increases with distance from the soma.

soma g = 0.0013846 mho/cm2
dendrite g (300-350 um away) = 0.0125 mho/cm2
see Table 1 in th paper

ENDCOMMENT

 UNITS {
        (mA) = (milliamp)
        (mV) = (millivolt)
}
 
NEURON {
        SUFFIX Ih
        USEION h READ eh WRITE ih VALENCE 1
        RANGE gkhbar,ih
        GLOBAL rinf, tau_r
}
 
INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}
 
PARAMETER {
        v (mV)
        p = 5 (degC)
        dt (ms)
        gkhbar = 0.001385 (mho/cm2)			
        eh = -32.9 (mV)
}
 
STATE {
        r
}
 
ASSIGNED {
        ih (mA/cm2)
	rinf 
	tau_r	(ms)
}
 
BREAKPOINT {
        SOLVE state METHOD cnexp
        ih = gkhbar*r*(v - eh)
}
 
INITIAL {
	rates(v)
	r = rinf
}

DERIVATIVE state { :Computes state variable h at current v and dt.
	rates(v)
	r' = (rinf - r)/tau_r
}

PROCEDURE rates(v(mV)) {  :Computes rate and other constants at current v.
                      :Call once from HOC to initialize inf at resting v.
:        TABLE rinf, rexp, tau_r DEPEND dt, p FROM -200 TO 100 WITH 300
	rinf = 1/(1 + exp((v+84.1(mV))/10.2(mV)))
	tau_r = 100(ms) + 1(ms)/(exp(-17.9-0.116(/mV)*v)+exp(-1.84+0.09(/mV)*v))
:	rexp = 1 - exp(-dt/(tau_r))
}
 
UNITSON


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