TITLE nmda

COMMENT

NMDA-achtige geleidbaarheid; bewerking van Traub's NMDA gate

in CA3 model van 1991

g(t) factor is hier [k+]o afhankelijk gemaakt

Onvolkomenheid is dat dit mechanisme direct naar de stromen ik en ina

schrijft. Realistischer is het om een mechanisme 'synapse' de passieve

geleidbaarheden gk_leak en gna_leak te veranderen.

1) Betere meting van de input resistance R_in.

2) 'Extracellular' werkt niet goed samen met pointprocesses. Nl. de netto

transmembraanstroom 'i_membrane' is niet meer nul.

Omdat een synapse per definitie een 'point process' is i.t.t. 'distributed

process', moet mech syn de waarde van gna_leak in mech leak veranderen.

mbv commando extern.?

bijgewerkt voor calciumgeleidbaarheid

ENDCOMMENT

UNITS {

(molar) = (1/liter)

(mV) = (millivolt)

(mA) = (milliamp)

(mM) = (millimolar)

:FARADAY = (faraday) (coulomb)

FARADAY = 96485.309 (coul)

R = (k-mole) (joule/degC)

PI = (pi) (1)

}

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

NEURON {

SUFFIX nmda

USEION k READ ko, ki, ek WRITE ik

USEION na READ nai, nao, ena WRITE ina

USEION ca READ cai, cao, eca WRITE ica VALENCE 2

GLOBAL mg, act_99, act_01, ina_99, ina_01, gbar, tau_ina, tau_act, scaleca

RANGE ik, ina, itot, ica, qna, qk

}

PARAMETER {

celsius=36 (degC)

gbar=1e-3 (mho/cm2)

tau_ina=2000 (ms)

tau_act=2 (ms)

act_99=20 (mM)

act_01=10 (mM)

ina_99=3.5 (mM)

ina_01=10 (mM)

mg=1.2 (mM)

scaleca=1

}

ASSIGNED {

v (mV)

itot (mA/cm2)

ik (mA/cm2)

ina (mA/cm2)

ica (mA/cm2)

ki (mM)

ko (mM)

ek (mV)

nai (mM)

nao (mM)

ena (mV)

cai (mM)

cao (mM)

eca (mV)

diam (um2)

}

STATE { ma mb ha hb qna qk }

BREAKPOINT {

SOLVE synstate METHOD sparse

ina= gbar*ma*ha*(v-ena)/(1+(mg/3)*exp(-.07*(70+v-60))) : ghk(v,nai,nao,1)

ik = gbar*ma*ha*(v-ek) /(1+(mg/3)*exp(-.07*(70+v-60))) : ghk(v,ki ,ko ,1)

ica= gbar*scaleca*ma*ha*(v-eca)/(1+(mg/3)*exp(-.07*(70+v-60))) : ghk(v,cai,cao,2)

itot=ina+ik+ica

:ma = 1 - mb

:ha = 1 - hb

}

INITIAL {

:SOLVE synstate STEADYSTATE sparse

ma=m_inf(ko)

mb=1-ma

ha=h_inf(ko)

hb=1-ha

qna=0

qk=0

ina= gbar*ma*ha*(v-ena)/(1+(mg/3)*exp(-.07*(70+v-60))) : ghk(v,nai,nao)

ik = gbar*ma*ha*(v-ek)/(1+(mg/3)*exp(-.07*(70+v-60))) : ghk(v,ki,ko)

ica= gbar*scaleca*ma*ha*(v-eca)/(1+(mg/3)*exp(-.07*(70+v-60))) : ghk(v,cai,cao,2)

itot=ina+ik+ica

}

LOCAL a1,a2,b1,b2

KINETIC synstate {

a1 = m_a(ko)

a2 = m_b(ko)

b1 = h_a(ko)

b2 = h_b(ko)

~ mb <-> ma (a1, a2)

~ hb <-> ha (b1, b2)

:CONSERVE ma + mb = 1

:CONSERVE ha + hb = 1

COMPARTMENT diam*diam*PI/4 { qna qk }

~ qna << (-ina*PI*diam*(1e4)/FARADAY)

~ qk << ( -ik*PI*diam*(1e4)/FARADAY)

}

FUNCTION m_a(ko) {

TABLE DEPEND act_99, act_01, tau_act FROM 0 TO 150 WITH 150

m_a = m_inf(ko)/tau_act

}

FUNCTION m_b(ko) {

TABLE DEPEND act_99, act_01, tau_act FROM 0 TO 150 WITH 150

m_b = (1-m_inf(ko))/tau_act

}

FUNCTION m_inf(ko) {

LOCAL kh, h

TABLE DEPEND act_99, act_01, tau_act FROM 0 TO 150 WITH 150

kh=(act_99+act_01)/2

h=-(kh-act_99)/4.59

m_inf=1/(1+(exp((kh-ko)/h)))

}

FUNCTION h_a(ko) {

TABLE DEPEND ina_99, ina_01, tau_ina FROM 0 TO 150 WITH 150

h_a = h_inf(ko)/tau_ina

}

FUNCTION h_b(ko) {

TABLE DEPEND ina_99, ina_01, tau_ina FROM 0 TO 150 WITH 150

h_b = (1-h_inf(ko))/tau_ina

}

FUNCTION h_inf(ko) {

LOCAL kh, h

TABLE DEPEND ina_99, ina_01, tau_ina FROM 0 TO 150 WITH 150

kh=(ina_99+ina_01)/2

h=-(ina_99-kh)/4.59

h_inf=1/(1+(exp((ko-kh)/h)))

}

FUNCTION ghk(v(mV), ci(mM), co(mM)) (.001 coul/cm3) {

LOCAL z, eci, eco

z = (1e-3)*1*FARADAY*v/(R*(celsius+273.11247574))

eco = co*efun(z)

eci = ci*efun(-z)

ghk = (.001)*1*FARADAY*(eci - eco)

}

FUNCTION efun(z) {

if (fabs(z) < 1e-4) {

efun = 1 - z/2

}else{

efun = z/(exp(z) - 1)

}

}