TITLE T calcium current : FORREST MD (2014) Two Compartment Model of the Cerebellar Purkinje Neuron COMMENT from "An Active Membrane Model of the Cerebellar Purkinje Cell 1. Simulation of Current Clamp in Slice" ENDCOMMENT UNITS { (mA) = (milliamp) (mV) = (millivolt) } NEURON { SUFFIX cat USEION ca READ cai, cao WRITE ica RANGE gcabar, ica, gca, minf, hinf, mexp, hexp } INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)} PARAMETER { v (mV) celsius = 37 (degC) dt (ms) gcabar = .0005 (mho/cm2) eca = 135 (mV) cai = 0.40e-4 (mM) : adjusted for eca=135mV cao = 2.4 (mM) } STATE { m h } ASSIGNED { ica (mA/cm2) gca minf hinf mexp hexp } BREAKPOINT { SOLVE states gca = gcabar * m*h ica = gca* (v-eca) } UNITSOFF INITIAL { rates(v) m = minf h = hinf } PROCEDURE states() { :Computes state variables m, h rates(v) : at the current v and dt. m = m + mexp*(minf-m) h = h + hexp*(hinf-h) } PROCEDURE rates(v) { :Computes rate and other constants at current v. :Call once from HOC to initialize inf at resting v. LOCAL q10, tinc, alpha, beta, sum TABLE minf, mexp, hinf, hexp DEPEND dt, celsius FROM -100 TO 100 WITH 200 q10 = 3^((celsius - 37)/10) tinc = -dt * q10 :"m" calcium activation system alpha = 2.6/(1+exp((v+21)/(-8))) beta = 0.18/(1+exp((v+40)/4)) sum = alpha + beta minf = alpha/sum mexp = 1 - exp(tinc*sum) :"h" calcium inactivation system alpha = 0.0025/(1+exp((v+40)/8)) beta = 0.19/(1+exp((v+50)/(-10))) sum = alpha + beta hinf = alpha/sum hexp = 1 - exp(tinc*sum) } UNITSON