CA1 pyramidal neuron: as a 2-layer NN and subthreshold synaptic summation (Poirazi et al 2003)

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Accession:20212
We developed a CA1 pyramidal cell model calibrated with a broad spectrum of in vitro data. Using simultaneous dendritic and somatic recordings, and combining results for two different response measures (peak vs. mean EPSP), two different stimulus formats (single shock vs. 50 Hz trains), and two different spatial integration conditions (within vs. between-branch summation), we found the cell's subthreshold responses to paired inputs are best described as a sum of nonlinear subunit responses, where the subunits correspond to different dendritic branches. In addition to suggesting a new type of experiment and providing testable predictions, our model shows how conclusions regarding synaptic arithmetic can be influenced by an array of seemingly innocuous experimental design choices.
References:
1 . Poirazi P, Brannon T, Mel BW (2003) Arithmetic of subthreshold synaptic summation in a model CA1 pyramidal cell. Neuron 37:977-87 [PubMed]
2 . Poirazi P, Brannon T, Mel BW (2003) Pyramidal neuron as two-layer neural network. Neuron 37:989-99 [PubMed]
3 . Poirazi P, Brannon T, Mel BW (2003ab-sup) Online Supplement: About the Model Neuron 37 Online:1-20
4 . Polsky A, Mel BW, Schiller J (2004) Computational subunits in thin dendrites of pyramidal cells. Nat Neurosci 7:621-7 [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,p; I Na,t; I L high threshold; I T low threshold; I A; I K; I M; I h; I K,Ca; I Calcium;
Gap Junctions:
Receptor(s): GabaA; GabaB; NMDA; Glutamate;
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Action Potential Initiation; Activity Patterns; Dendritic Action Potentials; Active Dendrites; Influence of Dendritic Geometry; Detailed Neuronal Models; Action Potentials; Depression; Delay;
Implementer(s): Poirazi, Panayiota [poirazi at imbb.forth.gr];
Search NeuronDB for information about:  Hippocampus CA1 pyramidal GLU cell; GabaA; GabaB; NMDA; Glutamate; I Na,p; I Na,t; I L high threshold; I T low threshold; I A; I K; I M; I h; I K,Ca; I Calcium;
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CA1_multi
mechanism
not-currently-used
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VClamp.omod *
                            
TITLE CaGk
: Calcium activated K channel.
: From Moczydlowski and Latorre (1983) J. Gen. Physiol. 82

UNITS {
        (molar) = (1/liter)
}

UNITS {
        (mV) =  (millivolt)
        (mA) =  (milliamp)
        (mM) =  (millimolar)
}


INDEPENDENT {t FROM 0 TO 1 WITH 100 (ms)}

NEURON {
        SUFFIX cagk
        USEION ca READ cai
        USEION k READ ek WRITE ik
        RANGE gkbar
        GLOBAL oinf, tau
}

UNITS {
        FARADAY = (faraday)  (kilocoulombs)
        R = 8.313424 (joule/degC)
}

PARAMETER {
        celsius=20      (degC)
        v               (mV)
        gkbar=.01       (mho/cm2)       : Maximum Permeability
        cai = 1e-3      (mM)
        ek              (mV)
        dt              (ms)
        

        d1 = .84
        d2 = 1.
        k1 = .18        (mM)
        k2 = .011       (mM)
        abar = .28      (/ms)
        bbar = .48      (/ms)
}

ASSIGNED {
        ik              (mA/cm2)
        oinf
        tau             (ms)
}

STATE { o }             : fraction of open channels

BREAKPOINT {
        SOLVE state
        ik = gkbar*o*(v - ek)
}

LOCAL fac

:if state_cagk is called from hoc, garbage or segmentation violation will
:result because range variables won't have correct pointer.  This is because
: only BREAKPOINT sets up the correct pointers to range variables.
PROCEDURE state() {     : exact when v held constant; integrates over dt step
        rate(v, cai)
        o = o + fac*(oinf - o)
        VERBATIM
        return 0;
        ENDVERBATIM
}

FUNCTION alp(v (mV), ca (mM)) (1/ms) { :callable from hoc
        alp = abar/(1 + exp1(k1,d1,v)/ca)
}

FUNCTION bet(v (mV), ca (mM)) (1/ms) { :callable from hoc
        bet = bbar/(1 + ca/exp1(k2,d2,v))
}

FUNCTION exp1(k (mM), d, v (mV)) (mM) { :callable from hoc
        exp1 = k*exp(-2*d*FARADAY*v/R/(273.15 + celsius))
}

PROCEDURE rate(v (mV), ca (mM)) { :callable from hoc
        LOCAL a
        a = alp(v,ca)
        tau = 1/(a + bet(v, ca))
        oinf = a*tau
        fac = (1 - exp(-dt/tau))
}

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