It looks like this

Code: Select all

```
COMMENT
This T-type calcium current was originally reported in Wang XJ et al 1991
This file supplies a version of this current identical to Quadroni and Knopfel 1994
except for gbar and Erev (see notes below).
Slight alterations by William Connelly Cardiff University 2013 for temperature dynamic reversal potential
ENDCOMMENT
NEURON {
SUFFIX lva
: NONSPECIFIC_CURRENT i
USEION ca READ cai, cao WRITE ica
RANGE Erev, g, gbar, i, cai
RANGE k, taum, minf, alpha_1, alpha_2, beta_1, beta_2, V_s
}
UNITS {
(S) = (siemens)
(mV) = (millivolt)
(mA) = (milliamp)
FARADAY = (faraday) (coulomb)
R = (k-mole) (joule/degC)
}
PARAMETER {
gbar = 0.4e-3 (S/cm2) < 0, 1e9 > : Quadroni and Knopfel use 166e-6
Erev = 120 (mV) : orig from Wang XJ et al 1991 was 120
: note: Quadroni and Knopfel 1994 table 1 use 80 instead
V_s = 0 (mV) : used to describe effect of changing extracellular [Ca]
: 0 corresponds to [Ca]outside = 3 mM (p 841)
qm = 3 : q10's for activation and inactivation
qh = 3 : from Coulter et al., J Physiol 414: 587, 1989
cai
cao
celsius (degC)
}
ASSIGNED {
ica (mA/cm2)
i (mA/cm2)
v (mV)
g (S/cm2)
k
alpha_1 (1)
alpha_2 (1)
beta_1 (1)
beta_2 (1)
carev
phi_m
phi_h
}
STATE { m h d }
BREAKPOINT {
SOLVE states METHOD cnexp
carev = (1e3) * (R*(celsius+273.15))/(2*FARADAY) * log (cao/cai)
g = gbar * m^3 * h
ica = g * (v - carev)
i = ica : used only to display the value of the current (section.i_lva(0.5))
}
INITIAL { LOCAL C, E
: assume that v has been constant for a long time
: (derivable from rate equations in DERIVATIVE block at equilibrium)
rates(v)
m = minf(v)
: h and d are intertwined so more complex than above equilib state for m
C = beta_1 / alpha_1
E = alpha_2 / beta_2
h = E / (E * C + E + C)
d = 1 - (1 + C) * h
phi_m = qm ^ ((celsius-24)/10)
phi_h = qh ^ ((celsius-24)/10)
}
DERIVATIVE states{
rates(v)
m' = (minf(v) - m)/taum(v) : alpham(v) * (1 - m) - betam(v) * m
h' = alpha_1 * (1 - h - d) - beta_1 * h
d' = beta_2 * (1 - h - d) - alpha_2 * d
}
FUNCTION minf(Vm (mV)) (1) {
minf = 1.0 / (1.0 + exp(-(Vm + V_s + 63)/7.8))
}
FUNCTION taum(Vm (mV)) (ms) {
taum = ((1.7 + exp( -(Vm + V_s + 28.8)/13.5 )) / (1.0 + exp( -(Vm + V_s + 63)/7.8) )) :/ phi_m
}
PROCEDURE rates(Vm(mV)) { LOCAL tau_2
k = (0.25 + exp((Vm + V_s + 83.5)/6.3))^0.5 - 0.5
tau_2 = (240.0 /((1 + exp((Vm + V_s + 37.4)/30)))) :/phi_h : same as tau2 p 842 equation (15)
alpha_1 = exp( -(Vm + V_s +160.3)/17.8 ) : p 842 equation (14)
beta_1 = k * alpha_1
alpha_2 = 1.0 / (( tau_2 * (1.0 + k) ))
beta_2 = k * alpha_2
}
```

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```
CVode-- At t = 2166.17 and h = 2.832e-05, the corrector
convergence failed repeatedly or with |h| = hmin.
CVode 7c10d8 dend[125] advance_tn failed, err=-7.
err=-7
nrniv: variable step integrator error
near line 228
TestDistrib(1)
^
fadvance( )
advance( )
step( )
continuerun(3000 )
```