Balance of excitation and inhibition (Carvalho and Buonomano 2009)

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Accession:125689
" ... Here, theoretical analyses reveal that excitatory synaptic strength controls the threshold of the neuronal input-output function, while inhibitory plasticity alters the threshold and gain. Experimentally, changes in the balance of excitation and inhibition in CA1 pyramidal neurons also altered their input-output function as predicted by the model. These results support the existence of two functional modes of plasticity that can be used to optimize information processing: threshold and gain plasticity."
Reference:
1 . Carvalho TP, Buonomano DV (2009) Differential effects of excitatory and inhibitory plasticity on synaptically driven neuronal input-output functions. Neuron 61:774-85 [PubMed]
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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):
Channel(s):
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON; MATLAB;
Model Concept(s): Synaptic Integration;
Implementer(s):
COMMENT

Integrate and Fire Unit

Rather than control v, when threshold is reached a strong
current (gON) is switched on for spikedur, the amplitude of the
spike is determined by the equilibrium potential of gON (eON).
At offset gOFF is turned on for one time step.  The repolarizing
potential is determined by the equilibrim potential of gOFF (eOFF).

I think I did this because I could not figure out how
to control v (outside of fadvance), which is transparently updated.

The AHP consists of an instantaneous current gAHP with time
constant tau

REBOUND: to simulate rebound I made the Eleak increase (thus increasing)
        resting membrane potential) whenever the cell is hyperpolarized.
ENDCOMMENT

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

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

NEURON {
   SUFFIX ExIAF
   NONSPECIFIC_CURRENT i
   GLOBAL spikedur, refact, tauAHP, eAHP, gAHPbar, ThrConst
        RANGE Thr, lastspike
        RANGE gPAS, ePAS, gAHP, AHPon, gON, gOFF, eON, eOFF
   :FOR PLASTICITY
        RANGE SetCa, AvgCa, Ca, tauDCCa, Gain
        RANGE ScaleFactor, Induction
   GLOBAL SCALE, GainConst
        GLOBAL tstop, terror
        RANGE B                          :Mg Block for postsynaptic cell
}


PARAMETER {
   v
   i               (mA/cm2)

   gPAS = 0.0001			:*0.001                    (mho/cm2)
   ePAS = -60              :                (mV)
   ePASconst = -60
   ThrConst = -45			:*-40		Somehow, this is the true Threshold!!	
   Thr  = -45				:*-40

   spikedur = 0.6			:*1    (ms)
   refact   = 3			:*2.0  (ms)

   gONconst  = 1		: (mho/cm2)
   gOFFconst = 1		: (mho/cm2)
   eON  = 40			: (mV)
   eOFF = -53			: *-60              (mV)

   tauAHP   = 0.2			: *0.1  (/ms)           : 1/tau = actual time constant of gAHP decay
   gAHPbar = 0.00035		: *0.00005 (mho/cm2)     : peak of AHP current. ACtually I think the units are S/cm2
   eAHP    = -90			: (mv)

   SetCa = 1
   tauDCCa = 10					:  in # of trials
   SCALE = 0						: USED TO GATE SCALING PLASTICITY
   GainConst = 0.1					: Learning Rate
   tstop
   terror

}

ASSIGNED {
        lastspike
        gAHP            (mho/cm2)
        AHPon                           : turns AHP on after spike ends

        gON             (mho/cm2)
        gOFF            (mho/cm2)

   Ca
   AvgCa
   ScaleFactor
   Induction
   Gain
   B

}


INITIAL {
   ePAS = ePASconst
   gAHP = 0
   AHPon     = -9e4

   gON = 0
   gOFF = 0

   terror = dt/10
   lastspike = -9e4

   Ca=0
   Induction = 0

}

BREAKPOINT {
        SOLVE update
        i = gPAS*(v-ePAS) + gAHP*(v-eAHP)+gON*(v-eON)+gOFF*(v-eOFF)
        B=mgblock(v)
}

PROCEDURE update() { LOCAL q, dv
: TURN ON AND OFF gON and gOFF to generate ACTION POTENTIAL
   gON = 0
   gOFF = 0
   q = (t-lastspike) - spikedur

   if (q>refact) {                              : refactory period over?
                if (v>Thr) {                    : threshod reached?
                        gON = gONconst          : turn spike current on
                        lastspike = t
                        Ca = Ca+1
                }
        }
        else if ( q < 0 ) {                     : spike still on
                gON=gONconst
        }
        else if (v > 0) {                               : turn spike off
                gOFF = gOFFconst
                gAHP = gAHP + gAHPbar
                AHPon = t
        }
        gAHP = gAHP - gAHP*tauAHP*dt

::: INDUCTION :::
::: HACK SO THAT INDUCTION IS RUN ON THE SECOND TO LAST TIMESTEP
    if ( t>(tstop-(2*dt)+terror) ) {
        : Induction==0(means that it has not got to INDUCTION yet
        : SCALE!=0 (means you are in a plastic mode)
        if (Induction==0) {
            SOLVE INDUCTION
            }
        }
::: END INDUCTION :::


}                              ::: END UPDATE :::


PROCEDURE INDUCTION() {

::: INDUCTION :::
    AvgCa = AvgCa+(Ca - AvgCa)/tauDCCa
    :ScaleFactor = 1+(GainConst*(SetCa-AvgCa)/(SetCa+AvgCa))*SCALE
    :ScaleFactor = (GainConst*(SetCa-AvgCa)/(SetCa+AvgCa))*SCALE
    ScaleFactor = GainConst*(SetCa-AvgCa)*SCALE

    ::: Triggers PLASTICITY IN EPSPplas
    Induction = 1
    :VERBATIM
    :     printf("INDUCTIONExIAF             t=%f            Ca=%f           %f\n",t,Ca,ScaleFactor);
    :ENDVERBATIM
::: END INDUCTION :::

}


FUNCTION mgblock(v(mV)) {
:mgblock(-100,0,50)(w/ 0.0062 = 0.9994,0.78,0.138
        TABLE
        FROM -140 TO 80 WITH 1000
        if (v>-58) {
           mgblock = 1/( 1+exp( (-35-v)/6 ) )
           :mgblock = 1/( 1+exp( (-30-v)/6 ) )
        } else {
           mgblock = 0
        }
}