Multicompartmental cerebellar granule cell model (Diwakar et al. 2009)

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Accession:116835
A detailed multicompartmental model was used to study neuronal electroresponsiveness of cerebellar granule cells in rats. Here we show that, in cerebellar granule cells, Na+ channels are enriched in the axon, especially in the hillock, but almost absent from soma and dendrites. Numerical simulations indicated that granule cells have a compact electrotonic structure allowing EPSPs to diffuse with little attenuation from dendrites to axon. The spike arose almost simultaneously along the whole axonal ascending branch and invaded the hillock, whose activation promoted spike back-propagation with marginal delay (<200 micros) and attenuation (<20 mV) into the somato-dendritic compartment. For details check the cited article.
Reference:
1 . Diwakar S, Magistretti J, Goldfarb M, Naldi G, D'Angelo E (2009) Axonal Na+ channels ensure fast spike activation and back-propagation in cerebellar granule cells. J Neurophysiol 101:519-32 [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: Cerebellum;
Cell Type(s): Cerebellum interneuron granule GLU cell;
Channel(s): I A; I M; I h; I K,Ca; I Sodium; I Calcium; I Potassium; I A, slow;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Action Potential Initiation; Active Dendrites; Detailed Neuronal Models; Axonal Action Potentials; Action Potentials; Intrinsic plasticity;
Implementer(s): Diwakar, Shyam [shyam at amrita.edu];
Search NeuronDB for information about:  Cerebellum interneuron granule GLU cell; I A; I M; I h; I K,Ca; I Sodium; I Calcium; I Potassium; I A, slow;
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GrC
fig10
readme.html
AmpaCOD.mod *
GRC_CA.mod *
GRC_CALC.mod *
GRC_GABA.mod *
GRC_KA.mod *
GRC_KCA.mod *
GRC_KIR.mod *
GRC_KM.mod *
GRC_KV.mod *
GRC_LKG1.mod *
GRC_LKG2.mod *
GRC_NA.mod *
NmdaS.mod *
Pregen.mod *
ComPanel.hoc
Grc_Cell.hoc
mosinit.hoc
Parametri.hoc
screenshot.jpg
simple.ses
Start.hoc
                            
TITLE Cerebellum Granule Cell Model

COMMENT
        CaHVA channel
   
	Author: E.D'Angelo, T.Nieus, A. Fontana
	Last revised: 8.5.2000
ENDCOMMENT
 
NEURON { 
	SUFFIX GRC_CA 
	USEION ca READ eca WRITE ica 
	RANGE gcabar, ica, g, alpha_s, beta_s, alpha_u, beta_u 
	RANGE Aalpha_s, Kalpha_s, V0alpha_s
	RANGE Abeta_s, Kbeta_s, V0beta_s
	RANGE Aalpha_u, Kalpha_u, V0alpha_u
	RANGE Abeta_u, Kbeta_u, V0beta_u
	RANGE s_inf, tau_s, u_inf, tau_u 
} 
 
UNITS { 
	(mA) = (milliamp) 
	(mV) = (millivolt) 
} 
 
PARAMETER { 
:Kalpha_s = 0.063 (/mV)  Checked!
:Kbeta_s = -0.039 (/mV) Checked!
:Kalpha_u = -0.055 (/mV) Checked!
:Kbeta_u = 0.012 (/mV) Checked!


	Aalpha_s = 0.04944 (/ms)
	Kalpha_s =  15.87301587302 (mV)
	V0alpha_s = -29.06 (mV)
	
	Abeta_s = 0.08298 (/ms)
	Kbeta_s =  -25.641 (mV)
	V0beta_s = -18.66 (mV)
	
	

	Aalpha_u = 0.0013 (/ms)
	Kalpha_u =  -18.183 (mV)
	V0alpha_u = -48 (mV)
		
	Abeta_u = 0.0013 (/ms)
	Kbeta_u =   83.33 (mV)
	V0beta_u = -48 (mV)

	v (mV) 
	gcabar= 0.00046 (mho/cm2) 
	eca = 129.33 (mV) 
	celsius = 30 (degC) 
} 

STATE { 
	s 
	u 
} 

ASSIGNED { 
	ica (mA/cm2) 
	s_inf 
	u_inf 
	tau_s (ms) 
	tau_u (ms) 
	g (mho/cm2) 
	alpha_s (/ms)
	beta_s (/ms)
	alpha_u (/ms)
	beta_u (/ms)
} 
 
INITIAL { 
	rate(v) 
	s = s_inf 
	u = u_inf 
} 
 
BREAKPOINT { 
	SOLVE states METHOD derivimplicit 
	g = gcabar*s*s*u 
	ica = g*(v - eca) 
	alpha_s = alp_s(v)
	beta_s = bet_s(v)
	alpha_u = alp_u(v)
	beta_u = bet_u(v)
}
 
DERIVATIVE states { 
	rate(v) 
	s' =(s_inf - s)/tau_s 
	u' =(u_inf - u)/tau_u 
} 
 
FUNCTION alp_s(v(mV))(/ms) { LOCAL Q10
	Q10 = 3^((celsius-20(degC))/10(degC))
	alp_s = Q10*Aalpha_s*exp((v-V0alpha_s)/Kalpha_s) 
} 
 
FUNCTION bet_s(v(mV))(/ms) { LOCAL Q10
	Q10 = 3^((celsius-20(degC))/10(degC))
	bet_s = Q10*Abeta_s*exp((v-V0beta_s)/Kbeta_s) 
} 
 
FUNCTION alp_u(v(mV))(/ms) { LOCAL Q10
	Q10 = 3^((celsius-20(degC))/10(degC))
	alp_u = Q10*Aalpha_u*exp((v-V0alpha_u)/Kalpha_u) 
} 
 
FUNCTION bet_u(v(mV))(/ms) { LOCAL Q10
	Q10 = 3^((celsius-20(degC))/10(degC))
	bet_u = Q10*Abeta_u*exp((v-V0beta_u)/Kbeta_u) 
} 
 
PROCEDURE rate(v (mV)) {LOCAL a_s, b_s, a_u, b_u 
	TABLE s_inf, tau_s, u_inf, tau_u 
	DEPEND Aalpha_s, Kalpha_s, V0alpha_s, 
	       Abeta_s, Kbeta_s, V0beta_s,
               Aalpha_u, Kalpha_u, V0alpha_u,
               Abeta_u, Kbeta_u, V0beta_u, celsius FROM -100 TO 30 WITH 13000 
	a_s = alp_s(v)  
	b_s = bet_s(v) 
	a_u = alp_u(v)  
	b_u = bet_u(v) 
	s_inf = a_s/(a_s + b_s) 
	tau_s = 1/(a_s + b_s) 
	u_inf = a_u/(a_u + b_u) 
	tau_u = 1/(a_u + b_u) 
}


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