TITLE high-threshold calcium (L-) current from hippocampal pyramidal cells COMMENT Equations from McCormick DA, Huguenard JR (1992) A model of the electrophysiological properties of thalamocortical relay neurons. J Neurophys 68(4): 1384-1400. See also Kay AR, Wong RK (1987) Calcium current activation kinetics in isolated pyramidal neurones of the Ca1 region of the mature guinea-pig hippocampus. J Physiol 392: 603-616. >< Temperature adjusts time constants measured at 23.5 degC. >< Written by Arthur Houweling for MyFirstNEURON. ENDCOMMENT NEURON { SUFFIX iL USEION ca READ cai,cao WRITE ica RANGE pca, minf, mtau, ica } UNITS { (mA) = (milliamp) (mV) = (millivolt) (mM) = (milli/liter) } PARAMETER { v (mV) celsius (degC) cai (mM) cao (mM) pca= 2.76e-4 (cm/s) } STATE { m } ASSIGNED { ica (mA/cm2) mtau (ms) minf tadj } BREAKPOINT { SOLVE states METHOD cnexp ica= pca* m^2* nrn_ghk( v, cai, cao, 2) } DERIVATIVE states { rates() m'= (minf- m)/ mtau } INITIAL { tadj= 3^ ((celsius- 23.5)/ 10) rates() m= minf } PROCEDURE rates() { LOCAL a,b UNITSOFF a= 1.6/ (1+ exp(-0.072* (v- 5))) b= 0.02* vtrap(-(v- 1.31), 5.36) mtau= 1/ (a+ b)/ tadj minf= 1/ (1+ exp((v+ 10)/ -10)) } FUNCTION vtrap( x, c) { :check for zero in denominator of rate equations if (fabs(x/ c)< 1e-6) { vtrap= c+ x/ 2 } else { vtrap= x/ (1- exp(-x/ c)) } }