CA1 pyramidal neuron: synaptically-induced bAP predicts synapse location (Sterratt et al. 2012)

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Accession:144490
This is an adaptation of Poirazi et al.'s (2003) CA1 model that is used to measure BAP-induced voltage and calcium signals in spines after simulated Schaffer collateral synapse stimulation. In the model, the peak calcium concentration is highly correlated with soma-synapse distance under a number of physiologically-realistic suprathreshold stimulation regimes and for a range of dendritic morphologies. There are also simulations demonstrating that peak calcium can be used to set up a synaptic democracy in a homeostatic manner, whereby synapses regulate their synaptic strength on the basis of the difference between peak calcium and a uniform target value.
Reference:
1 . Sterratt DC, Groen MR, Meredith RM, van Ooyen A (2012) Spine calcium transients induced by synaptically-evoked action potentials can predict synapse location and establish synaptic democracy. PLoS Comput Biol 8:e1002545 [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:
Cell Type(s): Hippocampus CA1 pyramidal GLU cell;
Channel(s): I Na,t; I L high threshold; I T low threshold; I A; I K; I M; I Mixed; I R; I_AHP;
Gap Junctions:
Receptor(s): AMPA; NMDA;
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Dendritic Action Potentials; Synaptic Plasticity;
Implementer(s): Sterratt, David ; Groen, Martine R [martine.groen at gmail.com];
Search NeuronDB for information about:  Hippocampus CA1 pyramidal GLU cell; AMPA; NMDA; I Na,t; I L high threshold; I T low threshold; I A; I K; I M; I Mixed; I R; I_AHP;
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bpap
CA1_multi
mechanism
cad.mod *
cagk.mod *
cal.mod *
calH.mod *
car.mod *
cat.mod *
d3.mod *
gabaa.mod *
gabab.mod *
glutamate.mod *
h.mod *
hha_old.mod *
hha2.mod *
kadist.mod *
kaprox.mod *
kca.mod *
km.mod *
nap.mod *
nmda.mod *
somacar.mod *
mosinit.hoc.old *
mosinit.poirazi.hoc *
                            
TITLE Slow Ca-dependent potassium current
                            :
                            :   Ca++ dependent K+ current IC responsible for slow AHP
                            :   Differential equations
                            :
                            :   Model based on a first order kinetic scheme
                            :
                            :       + n cai <->     (alpha,beta)
                            :
                            :   Following this model, the activation fct will be half-activated at 
                            :   a concentration of Cai = (beta/alpha)^(1/n) = cac (parameter)
                            :
                            :   The mod file is here written for the case n=2 (2 binding sites)
                            :   ---------------------------------------------
                            :
                            :   This current models the "slow" IK[Ca] (IAHP): 
                            :      - potassium current
                            :      - activated by intracellular calcium
                            :      - NOT voltage dependent
                            :
                            :   A minimal value for the time constant has been added
                            :
                            :   Ref: Destexhe et al., J. Neurophysiology 72: 803-818, 1994.
                            :   See also: http://www.cnl.salk.edu/~alain , http://cns.fmed.ulaval.ca
                            :   modifications by Yiota Poirazi 2001 (poirazi@LNC.usc.edu)
			    :   taumin = 0.5 ms instead of 0.1 ms	

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

                            NEURON {
                                    SUFFIX kca
                                    USEION k READ ek WRITE ik
                                    USEION ca READ cai
                                    RANGE gk, gbar, m_inf, tau_m
                                    GLOBAL beta, cac
                            }


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


                            PARAMETER {
                                    v               (mV)
                                    celsius = 36    (degC)
                                    ek      = -80   (mV)
                                    cai     = 2.4e-5 (mM)           : initial [Ca]i
                                    gbar    = 0.01   (mho/cm2)
                                    beta    = 0.03   (1/ms)          : backward rate constant
                                    cac     = 0.025  (mM)            : middle point of activation fct
       				    taumin  = 0.5    (ms)            : minimal value of the time cst
                                    gk
                                  }


                            STATE {m}        : activation variable to be solved in the DEs       

                            ASSIGNED {       : parameters needed to solve DE 
                                    ik      (mA/cm2)
                                    m_inf
                                    tau_m   (ms)
                                    tadj
                            }
                            BREAKPOINT { 
                                    SOLVE states METHOD derivimplicit
                                    gk = gbar*m*m*m     : maximum channel conductance
                                    ik = gk*(v - ek)    : potassium current induced by this channel
                            }

                            DERIVATIVE states { 
                                    evaluate_fct(v,cai)
                                    m' = (m_inf - m) / tau_m
                            }

                            UNITSOFF
                            INITIAL {
                            :
                            :  activation kinetics are assumed to be at 22 deg. C
                            :  Q10 is assumed to be 3
                            :
                                    tadj = 3 ^ ((celsius-22.0)/10) : temperature-dependent adjastment factor
                                    evaluate_fct(v,cai)
                                    m = m_inf
                            }

                            PROCEDURE evaluate_fct(v(mV),cai(mM)) {  LOCAL car
                                    car = (cai/cac)^2
                                    m_inf = car / ( 1 + car )      : activation steady state value
                                    tau_m =  1 / beta / (1 + car) / tadj
                                    if(tau_m < taumin) { tau_m = taumin }   : activation min value of time cst
                            }
                            UNITSON

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