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104 lines
2.7 KiB
104 lines
2.7 KiB
TITLE klt.mod The low threshold conductance of 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 transient potassium current found in ventral cochlear |
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nucleus "Type I" cells, which are largely "stellate" or "multipolar" cells (Manis and |
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Marx, 1991; Rothman and Manis, 2003a,b; Manis et al, 1996). The current is likely |
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mediated by Kv4.2 potassium channel subunits, but this has not been directly |
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demonstrated. The specific implementation is described in Rothman and Manis, J. |
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Neurophysiol. 2003, in the appendix. Measurements were made from isolated |
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neurons from adult guinea pig, under reasonably stringent voltage clamp conditions. |
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The measured current is sensitive to 4-aminopyridine. |
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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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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 ka |
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USEION k READ ek WRITE ik |
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RANGE gbar, gka, ik |
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GLOBAL ainf, binf, cinf, atau, btau, ctau |
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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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gbar = 0.00477 (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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a b c |
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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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ik (mA/cm2) |
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ek (mV) |
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gka (mho/cm2) |
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ainf binf cinf |
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atau (ms) btau (ms) ctau (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 aexp, bexp, cexp |
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BREAKPOINT { |
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SOLVE states METHOD cnexp |
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gka = gbar*(a^4)*b*c |
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ik = gka*(v - ek) |
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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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a = ainf |
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b = binf |
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c = cinf |
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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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a' = (ainf - a)/atau |
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b' = (binf - b)/btau |
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c' = (cinf - c)/ctau |
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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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ainf = (1 / (1 + exp(-1*(v + 31) / 6 (mV))))^0.25 |
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binf = 1 / (1 + exp((v + 66) / 7 (mV)))^0.5 |
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cinf = 1 / (1 + exp((v + 66) / 7 (mV)))^0.5 |
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atau = (100 (ms)/ (7*exp((v+60) / 14 (mV)) + 29*exp(-(v+60) / 24 (mV)))) + 0.1 |
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atau = atau/q10 |
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btau = (1000 (ms) / (14*exp((v+60) / 27 (mV)) + 29*exp(-(v+60) / 24 (mV)))) + 1 |
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btau = btau/q10 |
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ctau = (90 (ms)/ (1 + exp((-66-v) / 17 (mV)))) + 10 |
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ctau = ctau/q10 |
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} |
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