Active dendrites and spike propagation in a hippocampal interneuron (Saraga et al 2003)

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We create multi-compartment models of an Oriens-Lacunosum/Moleculare (O-LM) hippocampal interneuron using passive properties, channel kinetics, densities and distributions specific to this cell type, and explore its signaling characteristics. We find that spike initiation depends on both location and amount of input, as well as the intrinsic properties of the interneuron. Distal synaptic input always produces strong back-propagating spikes whereas proximal input could produce both forward and back-propagating spikes depending on the input strength. Please see paper for more details.
1 . Saraga F, Wu CP, Zhang L, Skinner FK (2003) Active dendrites and spike propagation in multi-compartment models of oriens-lacunosum/moleculare hippocampal interneurons. J Physiol 552:673-89 [PubMed]
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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 Na,t; I A; I K; I h;
Gap Junctions:
Receptor(s): AMPA;
Simulation Environment: NEURON;
Model Concept(s): Action Potential Initiation; Dendritic Action Potentials; Active Dendrites; Influence of Dendritic Geometry; Detailed Neuronal Models; Action Potentials;
Implementer(s): Saraga, Fernanda [Fernanda.Saraga at];
Search NeuronDB for information about:  Hippocampus CA1 interneuron oriens alveus GABA cell; AMPA; I Na,t; I A; I K; I h;
IA channel


1.	Zhang, L. and McBain, J. Voltage-gated potassium currents in
	stratum oriens-alveus inhibitory neurons of the rat CA1
	hippocampus, J. Physiol. 488.3:647-660, 1995.

		Activation V1/2 = -14 mV
		slope = 16.6
		activation t = 5 ms
		Inactivation V1/2 = -71 mV
		slope = 7.3
		inactivation t = 15 ms
		recovery from inactivation = 142 ms

2.	Martina, M. et al. Functional and Molecular Differences between
	Voltage-gated K+ channels of fast-spiking interneurons and pyramidal
	neurons of rat hippocampus, J. Neurosci. 18(20):8111-8125, 1998.	
	(only the gkAbar is from this paper)

		gkabar = 0.0175 mho/cm2
		Activation V1/2 = -6.2 +/- 3.3 mV
		slope = 23.0 +/- 0.7 mV
		Inactivation V1/2 = -75.5 +/- 2.5 mV
		slope = 8.5 +/- 0.8 mV
		recovery from inactivation t = 165 +/- 49 ms  

3.	Warman, E.N. et al.  Reconstruction of Hippocampal CA1 pyramidal
	cell electrophysiology by computer simulation, J. Neurophysiol.
	71(6):2033-2045, 1994.

		gkabar = 0.01 mho/cm2
		(number taken from the work by Numann et al. in guinea pig
		CA1 neurons)


        (mA) = (milliamp)
        (mV) = (millivolt)
        SUFFIX IA
        USEION k READ ek WRITE ik
        RANGE gkAbar,ik
        GLOBAL ainf, binf, aexp, bexp, tau_b
        v (mV)
        p = 5 (degC)
        dt (ms)
        gkAbar = 0.0165 (mho/cm2)	:from Martina et al.
        ek = -90 (mV)
	tau_a = 5 (ms)
        a b
        ik (mA/cm2)
	ainf binf aexp bexp
        SOLVE deriv METHOD derivimplicit
        ik = gkAbar*a*b*(v - ek)
	a = ainf
	b = binf

DERIVATIVE deriv {  :Computes state variables m, h, and n rates(v)      
		: at the current v and dt.
        rates(v) : required to update inf and tau values
        a' = (ainf - a)/(tau_a)
        b' = (binf - b)/(tau_b)
PROCEDURE rates(v) {  :Computes rate and other constants at current v.
                      :Call once from HOC to initialize inf at resting v.
        LOCAL alpha_b, beta_b
	TABLE ainf, aexp, binf, bexp, tau_a, tau_b  DEPEND dt, p FROM -200
TO 100 WITH 300
	alpha_b = 0.000009/exp((v-26)/18.5)
	beta_b = 0.014/(exp((v+70)/(-11))+0.2)
        ainf = 1/(1 + exp(-(v + 14)/16.6))
        aexp = 1 - exp(-dt/(tau_a))
	tau_b = 1/(alpha_b + beta_b)
        binf = 1/(1 + exp((v + 71)/7.3))
        bexp = 1 - exp(-dt/(tau_b))