Functional impact of dendritic branch point morphology (Ferrante et al., 2013)

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Accession:146509
" ... Here, we first quantified the morphological variability of branch points from two-photon images of rat CA1 pyramidal neurons. We then investigated the geometrical features affecting spike initiation, propagation, and timing with a computational model validated by glutamate uncaging experiments. The results suggest that even subtle membrane readjustments at branch point could drastically alter the ability of synaptic input to generate, propagate, and time action potentials."
Reference:
1 . Ferrante M, Migliore M, Ascoli GA (2013) Functional Impact of Dendritic Branch-Point Morphology J. Neurosci. 33:2156-2165
Model Information (Click on a link to find other models with that property)
Model Type: Synapse; Dendrite;
Brain Region(s)/Organism:
Cell Type(s): Hippocampus CA1 pyramidal cell;
Channel(s): I Na,t; I A; I K; I h;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s): Glutamate;
Simulation Environment: NEURON;
Model Concept(s): Action Potential Initiation; Dendritic Action Potentials; Active Dendrites; Influence of Dendritic Geometry; Action Potentials; Conduction failure; Information transfer; Bifurcation;
Implementer(s): Ferrante, Michele [mferr133 at bu.edu];
Search NeuronDB for information about:  Hippocampus CA1 pyramidal cell; I Na,t; I A; I K; I h; Glutamate;
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Branch_Point_Tapering
readme.html
distr.mod *
h.mod *
kadist.mod *
kaprox.mod *
kdrca1.mod *
na3n.mod *
netstimm.mod *
morph.txt
mosinit.hoc
screenshot.png
tapering.hoc
                            
TITLE na3
: Na current 
: modified from Jeff Magee. M.Migliore may97
: added sh to account for higher threshold M.Migliore, Apr.2002

NEURON {
	SUFFIX na3
	USEION na READ ena WRITE ina
	RANGE  gbar, ar, sh
	GLOBAL minf, hinf, mtau, htau, sinf, taus,qinf, thinf
}

PARAMETER {
	sh   = 0	(mV)
	gbar = 0.010   	(mho/cm2)	
								
	tha  =  -30	(mV)		: v 1/2 for act	
	qa   = 7.2	(mV)		: act slope (4.5)		
	Ra   = 0.4	(/ms)		: open (v)		
	Rb   = 0.124 	(/ms)		: close (v)		

	thi1  = -45	(mV)		: v 1/2 for inact 	
	thi2  = -45 	(mV)		: v 1/2 for inact 	
	qd   = 1.5	(mV)	        : inact tau slope
	qg   = 1.5      (mV)
	mmin=0.02	
	hmin=0.5			
	q10=2
	Rg   = 0.01 	(/ms)		: inact recov (v) 	
	Rd   = .03 	(/ms)		: inact (v)	
	qq   = 10        (mV)
	tq   = -55      (mV)

	thinf  = -50 	(mV)		: inact inf slope	
	qinf  = 4 	(mV)		: inact inf slope 

        vhalfs=-60	(mV)		: slow inact.
        a0s=0.0003	(ms)		: a0s=b0s
        zetas=12	(1)
        gms=0.2		(1)
        smax=10		(ms)
        vvh=-58		(mV) 
        vvs=2		(mV)
        ar=1		(1)		: 1=no inact., 0=max inact.
	ena		(mV)            : must be explicitly def. in hoc
	celsius
	v 		(mV)
}


UNITS {
	(mA) = (milliamp)
	(mV) = (millivolt)
	(pS) = (picosiemens)
	(um) = (micron)
} 

ASSIGNED {
	ina 		(mA/cm2)
	thegna		(mho/cm2)
	minf 		hinf 		
	mtau (ms)	htau (ms) 	
	sinf (ms)	taus (ms)
}
 

STATE { m h s}

BREAKPOINT {
        SOLVE states METHOD cnexp
        thegna = gbar*m*m*m*h*s
	ina = thegna * (v - ena)
} 

INITIAL {
	trates(v,ar,sh)
	m=minf  
	h=hinf
	s=sinf
}


FUNCTION alpv(v(mV)) {
         alpv = 1/(1+exp((v-vvh-sh)/vvs))
}
        
FUNCTION alps(v(mV)) {  
  alps = exp(1.e-3*zetas*(v-vhalfs-sh)*9.648e4/(8.315*(273.16+celsius)))
}

FUNCTION bets(v(mV)) {
  bets = exp(1.e-3*zetas*gms*(v-vhalfs-sh)*9.648e4/(8.315*(273.16+celsius)))
}

LOCAL mexp, hexp, sexp

DERIVATIVE states {   
        trates(v,ar,sh)      
        m' = (minf-m)/mtau
        h' = (hinf-h)/htau
        s' = (sinf - s)/taus
}

PROCEDURE trates(vm,a2,sh2) {  
        LOCAL  a, b, c, qt
        qt=q10^((celsius-24)/10)
	a = trap0(vm,tha+sh2,Ra,qa)
	b = trap0(-vm,-tha-sh2,Rb,qa)
	mtau = 1/(a+b)/qt
        if (mtau<mmin) {mtau=mmin}
	minf = a/(a+b)

	a = trap0(vm,thi1+sh2,Rd,qd)
	b = trap0(-vm,-thi2-sh2,Rg,qg)
	htau =  1/(a+b)/qt
        if (htau<hmin) {htau=hmin}
	hinf = 1/(1+exp((vm-thinf-sh2)/qinf))
	c=alpv(vm)
        sinf = c+a2*(1-c)
        taus = bets(vm)/(a0s*(1+alps(vm)))
        if (taus<smax) {taus=smax}
}

FUNCTION trap0(v,th,a,q) {
	if (fabs(v-th) > 1e-6) {
	        trap0 = a * (v - th) / (1 - exp(-(v - th)/q))
	} else {
	        trap0 = a * q
 	}
}	

        

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