TITLE HH T-type calcium channel NEURON { SUFFIX Icat USEION ca WRITE ica RANGE gbar, ica, g, h, m, sha, shi, k_tauH GLOBAL minf, hinf, mtau, htau } UNITS { (mA) = (milliamp) (mV) = (millivolt) } PARAMETER { v (mV) gbar = 0.036 (mho/cm2) <0,1e9> e = 100 (mV) sha = 0 shi = 0 k_tauH = 1 } STATE { m h g (mho/cm2) } ASSIGNED { ica (mA/cm2) minf hinf mtau (ms) htau (ms) } INITIAL { rates(v) m = minf h = hinf } BREAKPOINT { SOLVE states METHOD cnexp g = gbar*m*m*h ica = g*(v - e) } DERIVATIVE states { : computes state variables m and h at present v, t rates(v) m' = (minf - m)/mtau h' = (hinf - h)/htau } PROCEDURE rates(v(mV)) { UNITSOFF mtau = 1.5 + 3.5/(exp(-(v+30-sha)/15) + exp((v+30-sha)/(15))) minf = 1/(1+exp(-(v+44-sha)/5.5)) htau = 10 + 40/(exp(-(v+50-shi)/15) + exp((v+50-shi)/(15))) hinf = k_tauH*1/(1+exp((v+70-shi)/(4))) UNITSON }