## A time-dependent tha

NMODL and the Channel Builder.
qianhao
Posts: 2
Joined: Mon Sep 14, 2009 7:42 am

### A time-dependent tha

Hi Ted,
In a mod file of sodium channel Hodgkin-Huxley style kinetics, tha is a parameter that used to determine the 1/2 voltage of activation. Tha is always a constant during the stimulation. However, I want to make it change with time. For instance, tha will become more and more negtive with the time going. What should I do? I have tried to declare tha in ASSIGNED block and write the arithmetic expression (such as tha=-28+10*exp(-1*t/0.01)) in the same PROCEDURE which is also used to calculate minf & mtau, but it doesn't work.
ted
Posts: 5819
Joined: Wed May 18, 2005 4:50 pm
Location: Yale University School of Medicine
Contact:

### Re: A time-dependent tha

qianhao wrote:tha=-28+10*exp(-1*t/0.01))
tha = -18 at t==0 and collapses toward -28 with a time constant of 0.01 ms. By t==0.05 ms, tha is practically identical to -28. Is that what you want?
qianhao
Posts: 2
Joined: Mon Sep 14, 2009 7:42 am

### Re: A time-dependent tha

Thank you! Ted.
I have resolve this problem. The wrong point in my code is that

Code: Select all

``````TABLE minf,  hinf, mtau, htau, tha
DEPEND  celsius, temp, Ra, Rb, Rd, Rg,  thi1, thi2, qa, qi, qinf
FROM vmin TO vmax WITH 199
......
tha = -28+10*(1-exp(-1*t/20))
......``````
It means that t will be a constant during the calculation of m & h, isn't it?
ted