Voltage- and Branch-specific Climbing Fiber Responses in Purkinje Cells (Zang et al 2018)

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Accession:243446
"Climbing fibers (CFs) provide instructive signals driving cerebellar learning, but mechanisms causing the variable CF responses in Purkinje cells (PCs) are not fully understood. Using a new experimentally validated PC model, we unveil the ionic mechanisms underlying CF-evoked distinct spike waveforms on different parts of the PC. We demonstrate that voltage can gate both the amplitude and the spatial range of CF-evoked Ca2+ influx by the availability of K+ currents. ... The voltage- and branch-specific CF responses can increase dendritic computational capacity and enable PCs to actively integrate CF signals."
Reference:
1 . Zang Y, Dieudonné S, De Schutter E (2018) Voltage- and Branch-Specific Climbing Fiber Responses in Purkinje Cells Cell Reports 24(6):1536-1549 [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 Purkinje GABA cell;
Channel(s): Ca pump; I K; I K,Ca; I Na,p; I h;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Action Potential Initiation; Active Dendrites; Synaptic Integration; Dendritic Action Potentials; Detailed Neuronal Models;
Implementer(s): Zang, Yunliang ;
Search NeuronDB for information about:  Cerebellum Purkinje GABA cell; I Na,p; I K; I h; I K,Ca; Ca pump;
TITLE P-type calcium channel

COMMENT

According to Benton&Raman data
lower threshold but relatively large time constant compared with Sungho's model (According to Bruce Bean)
Also the ssa is steep. In this model, it is better not to shift the SSA to the left.
time speeded up by 2 times May 9 2016 (no longer)
ENDCOMMENT

NEURON {
	SUFFIX newCaP
	USEION ca READ cai, cao WRITE ica
	RANGE pcabar, ica,vshift,kt
	GLOBAL minf, taum
	GLOBAL monovalConc, monovalPerm
:	THREADSAFE
}

UNITS {
	(mV) = (millivolt)
	(mA) = (milliamp)
	(nA) = (nanoamp)
	(pA) = (picoamp)
	(S)  = (siemens)
	(nS) = (nanosiemens)
	(pS) = (picosiemens)
	(um) = (micron)
	(molar) = (1/liter)
	(mM) = (millimolar)		
}

CONSTANT {
	q10 = 3
	F = 9.6485e4 (coulombs)
	R = 8.3145 (joule/kelvin)

:	cv = 19 (mV)
:	ck = 5.5 (mV)
    cv = 30.5 (mV)
    ck = 4.113 (mV)
}

PARAMETER {
	v (mV)
	celsius (degC)

	cai (mM)
	cao (mM)
    vshift =0
	pcabar = 6e-5 (cm/s)
	monovalConc = 140 (mM)
	monovalPerm = 0
	kt=1
}

ASSIGNED {
	qt
	ica (mA/cm2)
      minf 
	taum (ms)
	T (kelvin)
	E (volt)
	zeta
}

STATE { m }

INITIAL {
	qt = q10^((celsius-22 (degC))/10 (degC))
	T = kelvinfkt( celsius )
	rates(v)
	m = minf
}

BREAKPOINT {
	SOLVE states METHOD cnexp
	ica = (1e3) * pcabar * m * ghk(v, cai, cao, 2)
}

DERIVATIVE states {
	rates(v)
	m' = (minf-m)/taum
}

FUNCTION ghk( v (mV), ci (mM), co (mM), z )  (coulombs/cm3) { 
	E = (1e-3) * v
      zeta = (z*F*E)/(R*T)	
	
	: ci = ci + (monovalPerm) * (monovalConc) :Monovalent permeability

	if ( fabs(1-exp(-zeta)) < 1e-6 ) {
	ghk = (1e-6) * (z*F) * (ci - co*exp(-zeta)) * (1 + zeta/2)
	} else {
	ghk = (1e-6) * (z*zeta*F) * (ci - co*exp(-zeta)) / (1-exp(-zeta))
	}
}

PROCEDURE rates( v (mV) ) {
	minf = 1 / ( 1 + exp(-(v+cv+vshift)/ck) )
	taum = (1e3) * taumfkt(v)/qt/kt
}

FUNCTION taumfkt( v (mV) ) (s) {
	UNITSOFF

    taumfkt = (0.0002 + 0.0007031 * exp(-((v+30+vshift)/14)^2))				:Raman data
:     taumfkt = (0.00002 + 0.00065 * exp(-((v+vshift)/40)^2))								:data from Biophysical Journal 108,2015: 578-584 David Naranjo
	UNITSON
}

FUNCTION kelvinfkt( t (degC) )  (kelvin) {
	UNITSOFF
	kelvinfkt = 273.19 + t
	UNITSON
}

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