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105 lines
2.7 KiB
105 lines
2.7 KiB
2 years ago
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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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