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100 lines
2.4 KiB
100 lines
2.4 KiB
TITLE na.mod A sodium channel for cochlear nucleus neurons |
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COMMENT |
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NEURON implementation of Jason Rothman's measurements of VCN conductances. |
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This file implements the average brain sodium current used in the Rothman model. |
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In the absence of direct measurements in the VCN, this is a fair assumption. |
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The model differs from the one used in Rothman et al, (1993) in that the steep |
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voltage dependence of recovery from inactivation in that model is missing. This |
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may affect the refractory period. To use the other model, use najsr.mod instead. |
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Original implementation by Paul B. Manis, April (JHU) and Sept, (UNC)1999. |
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File split implementaiton, April 1, 2004. |
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Contact: pmanis@med.unc.edu |
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Modifed implementation; includes all temperature scaling, passes modlunit |
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7/10/2014 pbm |
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ENDCOMMENT |
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UNITS { |
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(mA) = (milliamp) |
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(mV) = (millivolt) |
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(nA) = (nanoamp) |
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} |
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NEURON { |
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THREADSAFE |
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SUFFIX na |
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USEION na READ ena WRITE ina |
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RANGE gbar, gna, ina |
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GLOBAL hinf, minf, htau, mtau |
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} |
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INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)} |
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PARAMETER { |
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v (mV) |
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dt (ms) |
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ena (mV) |
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gbar = 0.07958 (mho/cm2) <0,1e9> |
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q10tau = 3.0 |
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q10g = 2.0 |
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} |
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STATE { |
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m h |
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} |
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ASSIGNED { |
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celsius (degC) : model is defined on measurements made at room temp in Baltimore |
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ina (mA/cm2) |
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gna (mho/cm2) |
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minf hinf |
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mtau (ms) htau (ms) |
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qg () : computed q10 for gnabar based on q10g |
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q10 () |
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} |
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LOCAL mexp, hexp |
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BREAKPOINT { |
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SOLVE states METHOD cnexp |
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gna = qg*gbar*(m^3)*h |
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ina = gna*(v - ena) |
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} |
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INITIAL { |
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qg = q10g^((celsius-22)/10 (degC)) |
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q10 = q10tau^((celsius - 22)/10 (degC)) : if you don't like room temp, it can be changed! |
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rates(v) |
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m = minf |
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h = hinf |
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} |
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DERIVATIVE states { :Computes state variables m, h, and n |
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rates(v) : at the current v and dt. |
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m' = (minf - m)/mtau |
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h' = (hinf - h)/htau |
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} |
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PROCEDURE rates(v (mV)) { :Computes rate and other constants at current v. |
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:Call once from HOC to initialize inf at resting v. |
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: average sodium channel |
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minf = 1 / (1+exp(-(v + 38) / 7 (mV))) |
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hinf = 1 / (1+exp((v + 65) / 6 (mV))) |
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mtau = (10 (ms)/ (5*exp((v+60) / 18 (mV)) + 36*exp(-(v+60) / 25 (mV)))) + 0.04 |
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mtau = mtau/q10 |
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htau = (100 (ms)/ (7*exp((v+60) / 11 (mV)) + 10*exp(-(v+60) / 25 (mV)))) + 0.6 |
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htau = htau/q10 |
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} |
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