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109 lines
3.0 KiB
109 lines
3.0 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 low threshold potassium current found in several brainstem |
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nuclei of the auditory system, including the spherical and globular bushy cells |
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(Manis and Marx, 1991; Rothman and Manis, 2003a,b) and octopus cells (Bal and |
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Oertel, 2000) of the ventral cochlear nucleus, principal cells of the medial |
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nucleus of the trapzoid body (Brew and Forsythe, 1995, Wang and Kaczmarek, |
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1997) and neurons of the medial superior olive. The current is likely mediated by |
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heteromultimers of Kv1.1 and Kv1.2 potassium channel subunits. The specific |
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implementation is described in Rothman and Manis, J. Neurophysiol. 2003, in the |
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appendix. Measurements were made from isolated neurons from adult guinea pig, |
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under reasonably stringent voltage clamp conditions. The measured current is |
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sensitive to the mamba snake toxin dendrotoxin-I. |
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Similar conductrances are found in the homologous neurons of the avian auditory |
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system (Reyes and Rubel; Zhang and Trussell; Rathouz and Trussell), and the |
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conductance described here, in the absence of more detailed kinetic measurements |
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, is probably suitable for use in modeling that system. |
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Original implementation by Paul B. Manis, April (JHU) and Sept, (UNC)1999. |
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File split implementation, February 28, 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 klt |
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USEION k READ ek WRITE ik |
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RANGE gbar, gklt, ik, q10g |
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GLOBAL winf, zinf, wtau, ztau |
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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 = 0.01592 (mho/cm2) <0,1e9> |
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zss = 0.5 <0,1> : steady state inactivation of glt |
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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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w z |
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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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gklt (mho/cm2) |
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winf zinf |
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wtau (ms) ztau (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 wexp, zexp |
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BREAKPOINT { |
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SOLVE states METHOD cnexp |
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gklt = qg*gbar*(w^4)*z |
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ik = gklt*(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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w = winf |
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z = zinf |
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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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w' = (winf - w)/wtau |
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z' = (zinf - z)/ztau |
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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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winf = (1 / (1 + exp(-(v + 48) / 6 (mV))))^0.25 |
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zinf = zss + ((1-zss) / (1 + exp((v + 71) / 10 (mV)))) |
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wtau = (100 (ms)/ (6*exp((v+60) / 6 (mV)) + 16*exp(-(v+60) / 45 (mV)))) + 1.5 |
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wtau = wtau/q10 |
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ztau = (1000 (ms)/ (exp((v+60) / 20 (mV)) + exp(-(v+60) / 8 (mV)))) + 50 |
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ztau = ztau/q10 |
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} |
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