Purkinje cell: Synaptic activation predicts voltage control of burst-pause (Masoli & D'Angelo 2017)

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Accession:239421
"The dendritic processing in cerebellar Purkinje cells (PCs), which integrate synaptic inputs coming from hundreds of thousands granule cells and molecular layer interneurons, is still unclear. Here we have tested a leading hypothesis maintaining that the significant PC output code is represented by burst-pause responses (BPRs), by simulating PC responses in a biophysically detailed model that allowed to systematically explore a broad range of input patterns. BPRs were generated by input bursts and were more prominent in Zebrin positive than Zebrin negative (Z+ and Z-) PCs. Different combinations of parallel fiber and molecular layer interneuron synapses explained type I, II and III responses observed in vivo. BPRs were generated intrinsically by Ca-dependent K channel activation in the somato-dendritic compartment and the pause was reinforced by molecular layer interneuron inhibition. BPRs faithfully reported the duration and intensity of synaptic inputs, such that synaptic conductance tuned the number of spikes and release probability tuned their regularity in the millisecond range. ..."
Reference:
1 . Masoli S, D'Angelo E (2017) Synaptic Activation of a Detailed Purkinje Cell Model Predicts Voltage-Dependent Control of Burst-Pause Responses in Active Dendrites. Front Cell Neurosci 11:278 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Realistic Network; Synapse;
Brain Region(s)/Organism: Cerebellum;
Cell Type(s): Cerebellum Purkinje GABA cell;
Channel(s): I Potassium; I K,Ca;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Detailed Neuronal Models; Bursting;
Implementer(s): Masoli, Stefano [stefano.masoli at unipv.it];
Search NeuronDB for information about:  Cerebellum Purkinje GABA cell; I K,Ca; I Potassium;
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Purkinjecell_2017
mod_files
Cav2_1.mod *
Cav3_1.mod *
Cav3_2.mod *
Cav3_3.mod *
cdp5.mod *
HCN1_Angeloetal2007.mod *
Kca11.mod *
Kca22.mod *
Kca31.mod *
Kir23.mod *
Kv11.mod *
Kv15.mod *
Kv33.mod *
Kv34.mod *
Kv43.mod *
Leak.mod *
Nav16.mod *
PC_Gaba_det_vi_alfa1.mod
PURKINJE_Ampa_det_vi.mod
UBC_TRP.mod
                            
TITLE Low threshold calcium current
:
:   Ca++ current responsible for low threshold spikes (LTS)
:   RETICULAR THALAMUS
:   Differential equations
:
:   Model of Huguenard & McCormick, J Neurophysiol 68: 1373-1383, 1992.
:   
:   Written by Alain Destexhe, Salk Institute, Sept 18, 1992
:   
:    - Biophysical properties of the T current were from recordings of
:    - human recombinant Cav3.2 T-channel in HEK-293 cells
:    - see Vitko et al., J. Neurosci 25(19) :4844-4855, 2005
:    - Q10 and shift parameters are fixed 
:   
:
:   Suffix from CaT3_2 to Cav3_2

INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}

NEURON {
	SUFFIX Cav3_2
	USEION ca READ cai, cao WRITE ica
	RANGE gcabar, m_inf, tau_m, h_inf, tau_h, shift, i,ica
}

UNITS {
	(molar) = (1/liter)
	(mV) =	(millivolt)
	(mA) =	(milliamp)
	(mM) =	(millimolar)

	FARADAY = (faraday) (coulomb)
	R = (k-mole) (joule/degC)
}

PARAMETER {
	v		(mV)
	celsius	= 36	(degC)
:	eca	= 120	(mV)
	gcabar	= .0008	(mho/cm2)
	shift	= 0 	(mV)
	cai	= 2.4e-4 (mM)		: adjusted for eca=120 mV
	cao	= 2	(mM)
}

STATE {
	m h
}

ASSIGNED {
	ica	(mA/cm2)
	carev	(mV)
	m_inf
	tau_m	(ms)
	h_inf
	tau_h	(ms)
	phi_m
	phi_h
	i	(mA/cm2)
}

BREAKPOINT {
	SOLVE castate METHOD cnexp
	carev = (1e3) * (R*(celsius+273.15))/(2*FARADAY) * log (cao/cai)
	ica = gcabar * m*m*h * (v-carev)
	i = ica		: diagnostic i added to display the current
}

DERIVATIVE castate {
	evaluate_fct(v)

	m' = (m_inf - m) / tau_m
	h' = (h_inf - h) / tau_h
}

UNITSOFF
INITIAL {
:
:   Activation functions and kinetics were obtained from
:   Vitko et al., 2005 at 23-25 deg.
:   Transformation to 36 deg assuming Q10 of 5 and 3 for m and h
:   (as in Coulter et al., J Physiol 414: 587, 1989)
:
	phi_m = 5 ^ (12/10)
	phi_h = 3 ^ (12/10)

	evaluate_fct(v)

	m = m_inf
	h = h_inf
}

PROCEDURE evaluate_fct(v(mV)) { 
:

	m_inf = 1.0 / ( 1 + exp(-(v+shift+54.8)/7.4) )
	h_inf = 1.0 / ( 1 + exp((v+shift+85.5)/7.18) )

	tau_m = ( 1.9 + 1.0 / ( exp((v+shift+37.0)/11.9) + exp(-(v+shift+131.6)/21) ) ) / phi_m
	tau_h = 13.7 + (1942 + exp((v+shift+164)/9.2)) / (1 + exp((v+shift+89.3)/3.7) ) / phi_h
}
UNITSON

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